JPH10270325A - Exposure light source, exposure method, exposure apparatus, and method of manufacturing semiconductor device - Google Patents

Abstract

(57) [Problem] To provide an exposure light source capable of stably generating a narrow band laser beam having a sufficiently high average output in a vacuum ultraviolet region for a long time. SOLUTION: A laser beam L1 extracted from a XeCl excimer laser 101 strikes a beam splitter 105a, and about 30% of its power is supplied to a dye laser oscillator 1.
The laser light L3 having a wavelength of 416 nm oscillates as the excitation light source 02. In the dye laser oscillator 102, an etalon 110, which is a band narrowing element, is used, and the band of the laser beam L3 is narrowed. The laser light L3 is transmitted through the beam splitter 105a, is amplified by the dye laser amplifier 103 that performs an amplification operation with the laser light L4 having a power of about 70%, which is incident via the mirror 111, and is amplified in the wavelength converter 104. The light is focused in the nonlinear optical crystal 112. Thereby, the laser light L having a wavelength of 208 nm, which is the second harmonic, is obtained.
6 is generated and used as exposure light L7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure light source, an exposure technique, and a semiconductor device manufacturing technique, and more particularly to a technique effective when applied to a photolithography technique using laser light in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art There are various types of performance required for an exposure apparatus (sometimes called a stepper) as a photolithography technique, such as resolution, alignment accuracy, processing ability, and apparatus reliability. Among them, the resolution R directly leading to the miniaturization of the pattern is R = k · λ / N
A (k: constant, λ: exposure wavelength, NA: numerical aperture of the projection lens). Therefore, in order to obtain good resolution, the optical parameter called the exposure wavelength λ is an important factor.

In a conventional stepper, a g-line (wavelength: 436 nm) or an i-line (wavelength: 365 nm) of a mercury lamp is mainly used.
Has been used as an exposure light source, but a KrF excimer laser having a wavelength of 248 nm has come to be used as an exposure light source having a shorter wavelength to realize a finer processing line width.

As a performance required for a KrF excimer laser as an exposure light source, the wavelength width of the oscillating laser light must be narrow. That is, it is required to narrow the wavelength band, and it is necessary to reduce the wavelength to about 1 pm or less. The reason for this is that as the wavelength decreases, the wavelength dispersion of the refractive index of the lens material of the reduction projection lens of the stepper increases, and the focal length of the lens varies depending on the wavelength. This is because if the wavelength of the laser beam is wide, a sharp image cannot be obtained.

As an exposure light source for performing finer processing as next-generation photolithography, a wavelength of 1
Use of a 93 nm ArF excimer laser is also being studied.

In this connection, for example, in
Laser Society of Japan, 16th Annual Conference, Preliminary Lecture Book, 25pVII4 (pages 96 to 99).

[0007]

The technical problem of the exposure light source using the ArF excimer laser is that even if a narrow band element is used for the laser, the wavelength width is about 10 pm and a stepper using a monochromatic lens is required. It is difficult to narrow the band to a wavelength width of 1 pm or less. The reason is that the wavelength of about 0.2 μm or less including the wavelength of 193 nm of the ArF excimer laser is in the vacuum ultraviolet region,
In general, the absorption rate of many optical materials is high. Therefore, the band-narrowing element itself may absorb the oscillating laser light and cause damage in a short period of time. Therefore, the band cannot be sufficiently narrowed. Alternatively, if the band is to be sufficiently narrowed, the laser output is reduced, so that a technical problem is that the throughput as a stepper is reduced. In other words, narrowing the band and increasing the output contradict each other,
It was difficult to satisfy both at the same time. In addition, regarding this, for example, monthly Semicond
actor World, November 1995, pp. 16-17.

A second technical problem is that the wavelength monitor for monitoring the wavelength of the laser beam deteriorates in a short period of time, similarly to the damage to the band-narrowing element. In an exposure apparatus using a single lens as a reduction projection lens, it is necessary to stabilize the wavelength of exposure light so as not to fluctuate, and therefore, it is necessary to constantly monitor the wavelength. A
In an rF excimer laser, laser light in a vacuum ultraviolet region is incident on a wavelength monitor. However, vacuum ultraviolet light has a high photon energy and easily deteriorates optical materials and the like.
Therefore, it is necessary to frequently replace the band-narrowing element and the wavelength monitor, which also raises the running cost.

A third technical problem is that the throughput of the exposure apparatus is low. That is, a semiconductor manufacturing apparatus such as a stepper is often operated continuously day and night, but an ArF excimer laser has a short gas life of 1,000,000 to 10,000,000 shots, and the laser gas needs to be changed frequently, and the apparatus is stopped every time. Therefore, there is a technical problem that the throughput of the apparatus is reduced.

As a fourth technical problem, as shown in FIG. 10, the wavelength of 193 nm of the ArF excimer laser is close to the absorption peak of a general chemically amplified resist made of an aromatic compound. It is too strong absorbed by the resist. This is described, for example, in the resist material handbook for semiconductor integrated circuits, Realize Inc., issued on July 31, 1996, pp. 99 to 100.

A fifth technical problem is that, in a conventional exposure apparatus using an ArF excimer laser, since the wavelength is short, an optical path for guiding a laser beam to the stepper body is set to nitrogen to avoid absorption of air during propagation. It is necessary to take measures such as filling with gas. However, this sometimes complicates the configuration of the entire apparatus. That is, the wavelength of about 0.2 microns or less is called the vacuum ultraviolet region,
The absorption rate of water vapor and carbon dioxide in the atmosphere increases,
Alternatively, oxygen in the atmosphere is decomposed by the laser light to generate ozone, which may absorb the laser light, and is difficult to propagate unless it is in a vacuum. The optical path of the laser light of the ArF excimer laser is, for example, the second optical path.
193nm Lithography International Symposium, Session 4.

A sixth technical problem is that the excimer laser has a high peak power, so that the lens material of the stepper is easily damaged. Therefore, in order to increase the average output without increasing the peak power, that is, without increasing the energy of the laser pulse, it is necessary to increase the number of pulse repetitions. However, in the case of excimer lasers, it is generally necessary to replace the laser gas in the discharge region for each pulse, so in order to increase the number of pulse repetitions, it is necessary to increase the circulation speed of the laser gas. In some cases, a large-sized blower was required, and the apparatus became large and complicated.

A first object of the present invention is to provide an exposure light source of A
It can overcome the above-mentioned various technical problems associated with the use of an rF excimer laser, and stably supplies a narrow band exposure light with a sufficient output at a wavelength of about 0.2 μm, which is a vacuum ultraviolet region, for a long time. It is to provide an exposure light source which can be used. Also,
An object of the present invention is to provide a high-throughput exposure technique by using this exposure light source.

It is a second object of the present invention to provide an exposure light source capable of suppressing deterioration of a band-narrowing element and a wavelength monitor and reducing running costs due to replacement thereof.

It is a third object of the present invention to provide an exposure light source capable of avoiding the absorption peak of a chemically amplified resist comprising an ordinary aromatic compound as the wavelength of the exposure light to be generated. Another object of the present invention is to provide an exposure light source capable of obtaining a high repetition number without increasing the size of the apparatus.

A fourth object of the present invention is to provide an exposure technique capable of simplifying equipment and reducing costs without having to fill an optical path for guiding exposure light to a stepper body with nitrogen gas or the like. is there.

A fifth object of the present invention is to provide an exposure light source capable of increasing the number of pulse repetitions without increasing the size of an apparatus using a large blower.

A sixth object of the present invention is to provide a semiconductor device manufacturing technique capable of efficiently manufacturing a semiconductor device having a design rule of a wavelength in a vacuum ultraviolet region.

[0019]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

For example, in order to achieve the first to third objects, an exposure light source according to the present invention comprises an excimer laser such as KrF (or XeCl) having a longer wavelength than an ArF excimer laser and a wavelength narrowing element. A dye laser oscillator, and a nonlinear optical crystal. The dye laser oscillator performs a laser operation using the KrF (or XeCl) excimer laser as an excitation light source, and outputs the laser light extracted from the dye laser oscillator to the nonlinear laser. Laser light generated by wavelength conversion by the optical crystal is used as exposure light.

In particular, in order to improve the throughput as an exposure apparatus, the reduction projection lens of the stepper is constituted by a quartz lens, and β-Ba is used as the nonlinear optical crystal.
It uses B ₂ O ₄ crystals (hereinafter abbreviated as BBO).

In order to achieve the third object, a wavelength monitor for monitoring the wavelength of the laser beam extracted from the dye laser oscillator is provided.

In order to achieve the fourth object, the KrF (or XeCl) excimer laser is installed on a different floor from the stepper main body, and the nonlinear optical crystal is arranged on the same floor as the exposure apparatus main body. Alternatively, the dye laser oscillator and the nonlinear optical crystal are arranged on the same floor as the main body of the exposure apparatus.

In order to achieve the fifth object, K
Using a plurality of rF (or XeCl) excimer lasers, the plurality of KrF (or XeCl) excimer lasers are oscillated at different timings, and a plurality of KrF (or XeCl) excimer lasers extracted from the plurality of KrF (or XeCl) excimer lasers are used. Out of the two laser beams, the two laser beams are incident on the same half mirror,
In addition, a dye laser amplifier is included or excitation light is irradiated from two directions to a dye which is a laser medium in the dye laser oscillator.

In order to achieve the sixth object,
The above-described exposure light source and exposure technique are applied to photolithography in a semiconductor device manufacturing technique.

An example of the operation of the present invention is as follows.

A dye laser using a KrF (or XeCl) excimer laser as an excitation light source can operate at a wavelength of about 340 nm or more depending on the type of dye. Therefore, the wavelength of the second harmonic generated as a result of wavelength conversion of the laser light extracted from the dye laser oscillator by the nonlinear optical crystal becomes about 170 nm or more, and it is possible to generate vacuum ultraviolet light having a wavelength of about 0.2 μm. However, in order to perform wavelength conversion particularly efficiently, BBO is used as a nonlinear optical crystal.
In this case, ultraviolet light having a wavelength of about 205 nm or more can be generated. As a result, sufficient transmittance is obtained in quartz, and the durability of the lens is improved in an exposure apparatus using a reduction projection lens made of a quartz lens, as compared with an ArF excimer laser having a wavelength of 193 nm.

Since the wavelength of the second harmonic is about 170 nm or more, a wavelength of 180 to 200 nm, which has a particularly high absorption in a chemically amplified resist made of an ordinary aromatic compound.
Exposure light of other wavelengths can be generated. In addition, the chemically amplified resist composed of the above-mentioned ordinary aromatic compound includes not only a resist having a benzene ring as a skeleton but also a resist having a shifted absorption peak.

In the present invention, KrF (or XeC
1) Since an excimer laser is used, the gas life is longer than that of an ArF excimer laser.

Further, in the present invention, a dye laser oscillator known to have wavelength tunability is used, so that the wavelength of exposure light can be adjusted.

In order to obtain exposure light having a narrow band, the band of the dye laser oscillator may be narrowed. Therefore, a necessary band narrowing element has a relatively long wavelength of about 340 nm or more. Those that can be used in the ultraviolet region can be used.

Similarly, by monitoring the wavelength of the laser light generated by the dye laser oscillator using a wavelength monitor, a wavelength monitor that can be used in a relatively long wavelength ultraviolet region having a wavelength of about 340 nm or more may be used. . If the wavelength of the laser light oscillated by the dye laser oscillator is stable, the wavelength of the second harmonic generated by the nonlinear optical crystal becomes stable even if the wavelength is converted by the nonlinear optical crystal.

Further, in the dye laser oscillator, since the beam diameter can be reduced by orders of magnitude as compared with the excimer laser, it is easy to oscillate in a single mode. That is, it is easy to generate a high-quality beam having a small divergence angle. In addition, a plurality of KrF (or XeCl) excimer lasers are used to oscillate at different timings, and two of the plurality of laser lights extracted from the plurality of KrF (or XeCl) excimer lasers are used. Is incident on the same half mirror, excitation light having twice the number of repetitions of the original laser light can be generated. However, since a plurality of excitation light beams are used, a dye laser amplifier is used, or the excitation light is applied to the dye as a laser medium from two directions. We can use without leaving. However, since only one dye laser is used, the exposure light does not become a plurality of beams.

The KrF (or Xe) used in the present invention
Since a Cl) excimer laser is used as an excitation light source for a dye laser, considering the conversion efficiency of the excimer laser to the dye laser and the wavelength conversion efficiency of the nonlinear optical crystal, the average output of 10 W which has been used in the conventional KrF stepper is considered. A laser output that is about one digit larger than that of a KrF excimer laser is required. Therefore, since the size of the apparatus becomes large, it is necessary to install the exposure light source on a floor different from the stepper main body. The floor used in this specification will be described. In a general downflow type clean room, different floors are provided above and below a grating, which is a floor on which a manufacturing apparatus is installed and a worker performs a normal manufacturing operation. However, in that case, the lower floor may be generally referred to as an underfloor.

However, if the exposure light source is installed on a different floor from the stepper body, the laser light must be transmitted across the floors, and the propagation distance of the laser light becomes longer. Therefore, in the present invention, since the excimer laser can be separated from the dye laser or the nonlinear optical crystal, the largest excimer laser can be installed on a floor different from the stepper body. In this case, the laser beam that propagates over a long distance has little attenuation during propagation because the wavelength of 248 nm (or 308 nm) of a KrF (or XeCl) excimer laser is not in the vacuum ultraviolet region. Alternatively, only the nonlinear optical crystal may be separated from the excimer laser. In this case, the laser light having a wavelength of about 340 nm or more of the KrF (or XeCl) excimer laser-excited dye laser is propagated over a long distance. Since it is not a band, attenuation during propagation is even smaller.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing a first embodiment of an exposure light source according to the present invention. The exposure light source 100 according to the present embodiment is roughly composed of a XeCl excimer laser 101, a dye laser oscillator 102, a dye laser amplifier 103, and a wavelength converter 104. X
Wavelength 30 extracted from eCl excimer laser 101
The 8 nm laser light L1 strikes the beam splitter 105a, and about 30% of its power is reflected here, and the reflected laser light L2 advances toward the dye laser oscillator 102,
It is used as the excitation light. Dye laser oscillator 102
, The output mirror 107 and the diffraction grating 108 constitute a resonator. The laser beam L2 passes through the lens 106a and passes through the dye solution 10 as a laser medium of the dye laser oscillator 102.
The light is focused on 9a. Thereby, the dye laser oscillator 102
Oscillates, and the laser beam L3 is extracted from the output mirror 107 to the outside of the resonator. The dye solution 109a is Bis
Dyes such as -MSB (1,4-bis (o-methylstyryl) benzene) and POPOP (1,4-bis [2- (5-phenyloxazol)] benzene) are suitable. For example, laser operation can be performed at a wavelength of 412 to 426 nm. Regarding this, for example, Osamu Uchino,
The other three, "XeCl laser-excited high-efficiency dye laser," are described in Laser Research, Vol. 6, No. 4, March 1979, pp. 57-59. Therefore, the dye laser oscillator 102 is set to oscillate at a wavelength of 416 nm by the diffraction grating 108 here. An etalon 110, which is a band narrowing element, is inserted into the resonator of the dye laser oscillator 102, so that the laser oscillates in a narrow band having a wavelength width of about 1 pm. The laser beam L3 is in a single mode.
That is, in the dye laser oscillator 102, the laser beam L2 as the excitation light is condensed at one point in the dye solution 109a, so that the beam diameter of the laser light oscillating in the resonator is about 0.3 m.
m, which is about two orders of magnitude smaller than that of an excimer laser.

Here, the laser oscillation mode will be described. The Fresnel number, which is a parameter that affects the oscillation mode of laser light, is proportional to the square of the beam diameter and inversely proportional to the resonator length. The smaller the Fresnel number is, the easier it is to oscillate only in low-order modes.

Generally, a dye laser oscillator can easily oscillate in a single mode as compared with a gas laser such as an excimer laser because the beam diameter can be reduced to 1 mm or less.

In the present invention, this feature is utilized. In the single mode, since the beam divergence angle is small,
The configuration is such that the wavelength conversion efficiency in the wavelength conversion unit 104 is increased. In contrast, a gas laser such as an excimer laser has a resonator length of about 2 m, which is one digit longer than that of the dye laser oscillator, but has a beam diameter of 30 mm to 50 mm, which is two digits larger. As a result, the Fresnel number increases by about 1000 times, and oscillation in a high-order multimode becomes easy.
Therefore, in the present invention, an excimer laser is used as an excitation light source of a dye laser without using a method of converting the wavelength of laser light oscillated by a gas laser such as an excimer laser. The laser beam L3 oscillated by the dye laser oscillator 102 enters the dye solution 109b constituting the dye laser amplifier 103. On the other hand, of the laser light L1 extracted from the XeCl excimer laser 101, the laser light L4 having a power of about 70% transmitted through the beam splitter 105a is reflected by the mirror 111, passes through the lens 106b, and is condensed on the dye solution 109b. And the amplified laser light L
5 is obtained. The laser beam L5 advances into the wavelength conversion unit 104, passes through the lens 106c, and is focused in the nonlinear optical crystal 112.

As a result, the second harmonic, wavelength 20
An 8-nm laser light L6 is generated. As the nonlinear optical crystal 112, a material having a high conversion efficiency in the ultraviolet region, such as BBO, is suitable. When BBO is used, the wavelength 20
It is known that a second harmonic of 5 nm or more can be generated. However, since the wavelength conversion efficiency is relatively low at wavelengths of 205 to 206 nm, a wavelength of 206 nm or more is preferred in the present invention. The laser light L6 passes through the lens 106d, becomes a parallel beam, and is used as the exposure light L7. Since the wavelength width of the laser light L6 is about 0.5 pm, which is half the wavelength width of the laser light L3, a monochromatic lens can be used in a stepper provided with the exposure light source of the present invention.

As described above, in the present invention, the wavelength width of the exposure light is determined by the dye laser oscillator 102, in which the etalon 110, which is a band narrowing element, is used. It is banded. Further, since the dye laser oscillator 102 uses the diffraction grating 108, by controlling the installation angle of the diffraction grating 108 by, for example, an actuator such as a piezo element (not shown), even if the same dye is used, Wavelength 10
It can be adjusted in the range of ２０20 nm. Further, by changing the kind of the dye, the oscillation wavelength can be adjusted in a wide range of several hundred nm. Thus, in the present embodiment, the fundamental wave is reduced to about 416
nm, that is, the second harmonic can be set at a wavelength of about 208 nm, and the absorption peak of a normal resist made of an aromatic compound can be avoided as shown in FIG. This makes it possible to use the normal resist in lithography using the main exposure light source.

As described above, in the exposure light source of the present invention, since the wavelength of the exposure light is about 210 nm, an aromatic resist having a benzene ring skeleton generally used conventionally can be used. Further, it is also possible to use the following new resist currently under development, which has a sufficient transmittance at the wavelength of 193 nm of the ArF excimer laser. In particular, when an alicyclic resist having an acrylic skeleton is used, it is easier to use than an ArF excimer laser in terms of transmittance. That is, the alicyclic resist shown in FIG. 13 (for example, AdMA-tBuM
A: A chemically amplified resist composed of an adamantyl methacrylate-t-butyl methacrylate copolymer. The transmittance of the alicyclic resist is as shown in the example of the transmittance of the dry etching resistant unit and the reactive unit in a ratio of 1: 1). Having a transmission band over a wide range from a wavelength of about 180 nm, that is, a wavelength 2
This is because the transmittance is higher around 10 nm. Regarding the alicyclic resist, for example, Satoshi Takechi "ArF resist using alicyclic group" SEMI Technology Symposium 96 Preprints SESSION3 Lithography 3-59 to 3-61 December 5, 1996 (English) 3-62 to 3-63 (Japanese).

On the other hand, another resist under development as an ArF excimer laser resist uses a polycyclic fused aromatic compound. This is the aromatic compound wavelength of 193n.
In some cases, the absorption peak of m is shifted to the longer wavelength side.
However, if a resist made of a polycyclic fused aromatic compound is used in the present invention, the absorption at a wavelength of about 210 nm is reduced.
In many cases, the absorption is higher than the absorption at the wavelength of 193 nm, and therefore, it is not suitable in the present invention. Therefore, in the present invention, it is particularly effective to use an alicyclic resist.

As described above, the exposure light source 100 of the first embodiment uses the second harmonic of the dye laser.
According to this, the pulse laser light as the exposure light L7 is also characterized by high energy stability. That is, the conventional A
In some cases, other than the rF excimer laser, the fifth harmonic of a YAG laser is used as an exposure light source having a wavelength of about 0.2 μm, and the exposure light has a wavelength of 213 nm. However, in this case, it is necessary to perform the wavelength conversion three times, but in the wavelength conversion, two types of laser beams having different wavelengths are combined, so that the number of times of the wavelength conversion is large. Becoming big was a technical challenge.
In contrast, in the present invention, since the second harmonic is used,
Since wavelength conversion is performed only once, pulse energy is also characterized by small variations in pulse energy. In optical lithography, in particular, it is necessary to reduce the energy variation of the exposure light. Therefore, the present invention has a particularly great effect among various laser systems that generate vacuum ultraviolet light by wavelength conversion. Regarding the exposure light source based on the wavelength conversion of the YAG laser, for example, in 1996, the Laser Society of Japan Academic Lecture, the 16th Annual Conference,
4pVII1 (pages 58 to 61).

As described above, in the present invention, the excimer laser is used as the excitation light source of the dye laser. However, the dye which is the laser medium of the dye laser generally has a wavelength width of several tens of nanometers.
It has a broad absorption spectrum of m or more. Therefore, it is not necessary to narrow the band of the excimer laser, which is the excitation light source, and it is not necessary to use a vacuum ultraviolet band narrowing element that has a short life and increases running costs.

In this embodiment, a part of the laser light L5 emitted from the dye laser amplifier 103 is extracted by the beam splitter 105b and
, Where the wavelength is constantly monitored. That is, in this embodiment, instead of monitoring the vacuum ultraviolet laser light (L7) used as the exposure light L7, the laser light L5 having a relatively long wavelength of 0.3 μm or more before the wavelength conversion is monitored. Even if a general wavelength monitor 113 is used, it does not deteriorate in a short period of time, and the running cost due to replacement of the wavelength monitor 113 can be reduced.

Note that a KrF excimer laser may be used instead of the XeCl excimer laser 101 of the present embodiment. In this case, the KrF excimer laser can be a KrF excimer laser of a conventional KrF stepper using the laser light of the KrF excimer laser as direct exposure light, and the exposure light source can be configured without purchasing a new KrF excimer laser. What is possible is a feature of the present invention. In this case, the KrF excimer laser for the KrF stepper generally includes a band-narrowing element for narrowing the wavelength of the laser light. On the other hand, in the present invention, since the excimer laser is used as the excitation light source of the dye laser, it is not necessary to narrow the wavelength of the laser light of the excimer laser. Therefore, the XeCl (or KrF) excimer laser required in the present invention is provided with KrF stepper Kr.
When an F excimer laser is used, it is preferable to use the F excimer laser with its band-narrowing element removed. The reason is that when the band-narrowing element is removed, the laser output generally increases. Even when a KrF excimer laser for a KrF stepper is used, KrF as a laser gas is converted to XeCl
Can be operated as a laser even if it is replaced, and can be reused as a XeCl excimer laser.

As described above, the exposure light source of the present invention is characterized in that the band of the dye laser is narrowed or the fundamental wave from the dye laser is monitored, thereby extending the life of the band narrowing element and the wavelength monitor. However, conventionally, a device that does not use a narrow-band element in an ArF excimer laser has been proposed, in which an ArF excimer laser is used as an amplifier. However, the present invention is characterized in that the ArF excimer laser itself is not used, and the XeCl excimer laser (or Kr
In F excimer lasers, other consumable hair such as a laser gas and a laser window (a window for extracting laser light from a discharge tube) have a much longer life than an ArF excimer laser, so that a XeCl excimer laser (or KrF excimer laser) is used. ). Therefore, ArF
Compared with a conventional device using an excimer laser as an amplifier, the lifetime of the device is longer and the throughput as an exposure device is improved. As for a conventional device using an ArF excimer laser as an amplifier, for example,
1994 41st Japan Society of Applied Physics Related Lectures, Proceedings, No. 3, page 928, 29a-E-1.

(Embodiment 2) Next, a first embodiment of the exposure apparatus of the present invention will be described with reference to FIG. FIG.
FIG. 1 is a conceptual diagram showing an example of a configuration of an exposure apparatus of the present embodiment.

The stepper 200 as the exposure apparatus according to the first embodiment includes a stepper body 150 and the exposure light source 100 shown in FIG. Exposure light source 10
The exposure light L7 having a wavelength of 208 nm taken out from the reference light 0 is reflected by the mirrors 201a and 201b, the beam is expanded by the beam expander 202, reflected by the mirror 201c, passes through the random phase plate 203, and passes through the random phase plate 203. The speckle noise is removed, and the light passes through the fly-eye lens 204 to have a uniform intensity distribution.
The reticle 206 passes through the reticle 206. Reticle 206
Is passed through a reduction projection lens 207 made of a quartz lens and impinges on a wafer 209 mounted on a stage 208. Thereby, the pattern on the reticle 206 is reduced and projected on the wafer 209. In the present embodiment, the reduction projection lens 207 is a monochromatic lens made of quartz. A which has been conventionally developed as a stepper light source
Since the wavelength width of the rF excimer laser is about 10 pm, it is difficult to use a monochromatic lens, and the use of an achromatic lens using fluorite and a stepper using a reflection optical system has been studied. On the other hand, since the wavelength width of the exposure light source 100 is about 0.5 pm as in the present embodiment, it is possible to use a stepper of a refractive optical system using a monochromatic lens.

Also, as in this embodiment, the exposure light source 10
In the case of 0, BBO is particularly used as the nonlinear optical crystal 112. However, when the second harmonic is generated by BBO, ultraviolet light having a wavelength of 205 nm or more can be obtained. Therefore, in the present embodiment, operation is performed at a wavelength of 208 nm.

According to this, the transmittance in quartz becomes higher than the transmittance of the ArF excimer laser at a wavelength of 193 nm, and the rate at which the reduced projection lens 207 made of quartz deteriorates due to the absorption of laser light is reduced. It is a feature of the present invention that the life of 207 is prolonged. That is, when the wavelength becomes 200 nm or less, the light absorptivity of quartz rapidly decreases. As a result,
The resist to be applied to the surface of the wafer 209 is also ArF
A general resist having a lower sensitivity than that of a high-sensitivity resist developed for an excimer laser can be used. In this regard, in the conventional exposure using an ArF excimer laser, a high-sensitivity resist that is sensitive to a laser beam with a sufficiently low output has been required so as not to deteriorate the reduction projection lens. However, this high-sensitivity resist has an etching characteristic. There have been technical problems such as poor quality, difficulty in developing a material having sufficient etching characteristics, and the fact that the developed material is expensive.

As described above, in the present invention, a reduction projection lens using a quartz lens can be used as in the conventional exposure apparatus. That is, since a reduction projection lens that is technically deeply established can be used, a reduction projection lens having a sufficiently large diameter can also be used, and as a result, an exposure apparatus having a high processing capability can be realized. If a semiconductor integrated circuit is manufactured using the exposure apparatus, the manufacturing time is short and the throughput is improved, so that the cost of the semiconductor integrated circuit can be reduced.

When BBO is used in the present invention, the wavelength is 208 nm in the above embodiment,
Actually, ultraviolet light having a wavelength of 205 nm or more can be generated. However, the wavelength conversion efficiency is relatively low at wavelengths of 205 to 206 nm, and as described above, a method using ultraviolet light of the fifth harmonic of 213 nm of the YAG laser has been proposed. Therefore, in the present invention, since it is effective in terms of resolution if used at a wavelength lower than the above-mentioned proposal, when BBO is used, it may be used particularly at a wavelength of 206 to 213 nm.

In this case, a semiconductor integrated circuit manufactured by a semiconductor manufacturing method using an exposure apparatus is particularly suitable for a semiconductor integrated circuit having a wavelength of 0.12 to 0.21 μm corresponding to about 60% of the wavelength of the exposure light. This is a design rule.

Further, since a monochromatic lens can be used as described above, a monochromatic lens made of only fluorite can be used as the reduction projection lens. As a result, the transmittance of fluorite in the vacuum ultraviolet region is higher than that of quartz, so that a stepper of a refractive optical system similar to the conventional one can use ultraviolet light having a wavelength of about 180 nm or less. To do this, the dye laser oscillator 102 shown in FIG. 1 is oscillated at about 340 nm, and its second harmonic wavelength is about 170 nm.
It is sufficient to generate ultraviolet light of nm. In that case, as the dye used in the dye laser oscillator 102 and the dye laser amplifier 103, for example, p-Terphenyl is suitable. As can be seen from FIG. 10, the exposure light having a wavelength of about 170 nm generated thereby is lower than the absorption peak (wavelength of about 190 nm) of a normal resist made of an aromatic compound, and the resist can be used.
Finer processing can be realized than when an ArF excimer laser having a wavelength of about 193 nm is used as an exposure light source. In addition, not only a resist having a benzene ring as a skeleton but also a resist having an absorption peak shifted to a longer wavelength side can be used as the above-mentioned ordinary resist. Further, in the reduction projection lens, since the absorptance at a wavelength of about 170 nm is relatively high, the reduction projection lens 207 may be air-cooled with helium or the like so as to absorb the exposure light and prevent the temperature from rising.

In this case, a semiconductor integrated circuit manufactured by a semiconductor manufacturing method using an exposure apparatus is particularly suitable for a semiconductor integrated circuit having a wavelength of 0.10 to 0.18 μm, which corresponds to about 60% of the wavelength of the exposure light. This is a design rule.

(Embodiment 3) FIG. 3 shows a second embodiment of the exposure apparatus of the present invention. FIG. 3 is a configuration diagram showing an example of an installation state of a stepper, which is an example of the exposure apparatus of the present embodiment, in a clean room.

In the stepper 300 of the present embodiment, FIG.
Stepper body 150 similar to stepper 200 illustrated in FIG.
Is used. The exposure light source is roughly divided into a XeCl excimer laser 302 and a wavelength conversion dye laser 303. The wavelength conversion dye laser 303 includes a dye laser oscillator 102, a dye laser amplifier 103, and the like as shown in FIG.
And a wavelength converter 104.

The stepper body 150 is located in the clean room 1
The XeCl excimer laser 302 is installed on the second floor 301a of the clean room. The second floor 301
Reference numeral a denotes a floor called a floor in a general downflow type clean room, on which various semiconductor manufacturing apparatuses are installed, and on which a worker performs work related to manufacturing. That is, the floor 30 of the floor 301a
Reference numeral 1 'denotes a floor having a mesh structure called grating, and purified air flows from the floor 301a to the floor 301a.
b.

The laser light L 30 as the excitation light extracted from the XeCl excimer laser 302 is
a, reflected by the mirror 304b and the mirror 304c, guided to the wavelength conversion dye laser 303, and used to excite the dye laser oscillator and dye laser amplifier therein. About 208 nm wavelength extracted from the wavelength conversion dye laser 303
Is reflected by the mirrors 304d and 304e, and is guided into the stepper main body 150. The dye solution necessary for the wavelength conversion dye laser 303 is guided from the dye laser auxiliary device 305 installed on the second floor 301a to the wavelength conversion dye laser 303 through the inside of the flexible tube 306. As a result, a large amount of the dye solution can be stored in the dye laser auxiliary device 305, so that there is no need to provide a dye solution storage tank in the wavelength conversion dye laser 303, and the wavelength conversion dye laser 303 can be made compact. The dye laser auxiliary device 305 includes a tank for storing a large amount of the dye solution, a heat exchanger for cooling the dye solution, a filter for purifying the dye solution, and the like.

In the present embodiment, the next largest XeCl
An excimer laser 302 is installed on a different floor from the stepper body 150. That is, the space occupied by the stepper 300 in the clean room can be reduced by providing a three-dimensional installation. In particular, in the present invention, a XeCl excimer laser 30 having a wavelength longer than ArF is used.
Since the laser light L30 from 2 is propagated between floors, there is no significant attenuation during propagation even if the optical path of the laser light L30 is not particularly filled with nitrogen gas or the like. Further, the stepper body 150 may be installed on the second floor 301a. In that case, the XeCl excimer laser 302 may be installed on the first floor 301b.

In particular, the KrF (or XeCl) excimer laser used in the present invention is an excitation light source for a dye laser, so that the device is much larger than an excimer laser like a conventional KrF (or ArF) stepper. Therefore, it is effective to install only the excimer laser on a floor different from the stepper main body as in the present embodiment in terms of the occupied space in the clean room. In addition, since the laser light L30 transmitted over a long distance between different floors is not the exposure light in the vacuum ultraviolet region, but has a wavelength of 308 nm of the XeCl excimer laser in the present embodiment, the optical path of the laser light L30 is made of nitrogen gas or the like. If not, there is no significant attenuation during propagation. In this embodiment, the dye laser is also separated from the excimer laser.
The same effect can be obtained by disposing only the wavelength conversion section made of the nonlinear optical crystal on the same floor as the stepper body. In this case, since the laser light transmitted between the floors is the laser light of the dye laser, the wavelength thereof is longer than the wavelength of the excimer laser, so that the attenuation during the transmission is further reduced.

(Embodiment 4) Next, a second embodiment of the exposure light source of the present invention will be described with reference to FIGS. FIG. 4 is a conceptual diagram showing an example of a configuration of an exposure light source according to a second embodiment of the present invention, and FIG. 5 is a conceptual diagram showing an example of a configuration of a laser amplifier constituting a part thereof. .

Two XeCl excimer lasers 401a and 401b are used as excitation light sources for dye lasers, which are components of the exposure light source 400 shown in FIG.
Is used. Both operate at a repetition rate of 500 Hz, but the oscillation timing is shifted by half the pulse interval. The laser beam L41 extracted from the XeCl excimer laser 401a is
The light is reflected at 02a and enters the half mirror 403. On the other hand, the laser light L42 extracted from the XeCl excimer laser 401b also enters the same half mirror 403. The half mirror 403 has a characteristic of transmitting 50% of a XeCl excimer laser beam having a wavelength of 308 nm and reflecting 50%. This allows the half mirror 40
The two laser beams L43 and L44 passing through the three XeCl excimer lasers 401a and 401
The laser light from b will be contained in half each.

These XeCl excimer lasers 401a
And 401b, the oscillation timing is shifted by half the pulse interval, so that the two laser beams L4
3 and the laser beam L44 are 1000 times the total number of repetitions of the respective XeCl excimer lasers 401a and 401b.
Hz. The laser beams L43 and L44 are respectively supplied to the mirror 402b, the half mirror 404b, the half mirror 404d, the mirror 402d, and the half mirror 4
04a, the half mirror 404c, and the mirror 402c, the dye laser oscillator 405,
Excitation lights L45a and L45 in the first-stage dye laser amplifier 406a and the second-stage dye laser amplifier 406b, respectively.
a, 47a and the excitation light L45b, 46b, 47b.

That is, in the dye laser oscillator 405 and the dye laser amplifiers 406a and 406b, a dye solution 411 as a laser medium flows in the dye cell 410 as illustrated in FIG. The two excitation lights travel from both sides of the dye cell 410 while being throttled through the cylindrical lenses 412a and 412b, respectively, and the dye solution 411 is formed.
A two-sided excitation method in which light is condensed inside is employed.

The dye laser oscillator 405 operated by the excitation light having a repetition rate of 1000 Hz oscillates at 1000 Hz, and the dye laser amplifiers 406a and 406b similarly amplify the excitation light of 1000 Hz. It is. Therefore, the nonlinear optical crystal 40 is incident upon the laser beam L48.
Exposure light L49, which is the second harmonic generated from 7, is also 100
0 Hz.

That is, in the present embodiment, the number of repetitions of the pump light is twice as high as that of one XeCl excimer laser, so that the total average power of the pump light is smaller than that in the case of using one XeCl excimer laser. Are the same,
The energy of one pulse can be halved. As a result, the peak power of each pulse is reduced by half, so that the reduction projection lens of the stepper is hardly damaged. In particular, when the wavelength of the exposure light is about 0.2 μm or less, absorption begins to increase even in quartz having a high transmittance in the ultraviolet region.
Since a high peak power of the exposure light easily causes damage, in a stepper using a conventional ArF excimer laser, damage to the lens of the stepper has been a serious technical problem.

As in the present embodiment, in the present invention, the laser light of the excimer laser is not used as the direct exposure light, but is used as the excitation light source of the dye laser. ), In which case the number of repetitions of the exposure light can be N times the number of repetitions of one excimer laser. Further, when a plurality of excimer lasers serving as excitation light sources are provided as in this embodiment to constitute an exposure light source having a high repetition rate, the effect is particularly great for a scan type stepper as described below.

That is, in a scan type stepper,
As shown in FIG. 11, a rectangular exposure field is scanned with respect to a rectangular chip formed on the wafer 209 to irradiate a rectangular exposure area corresponding to the chip with exposure light. For this reason, the irradiation area slightly shifts for each pulse of the exposure light, so that if the energy varies greatly from pulse to pulse, the exposure amount will be uneven. Therefore, as the pulse repetition number increases, the deviation of the irradiation region for each pulse can be reduced, and the unevenness in the exposure amount can be suppressed. That is, in the present invention, it is possible to increase the number of repetitions of the exposure light without modifying the excimer laser used to increase the circulation speed of the laser gas itself.

However, if an XeCl excimer laser is used as the excimer laser which is a constituent element of the present invention, it is generally easier to operate at a higher repetition rate when the average output is the same as that of the KrF excimer laser. Can be set to the repetition rate of the kHz class. As described above, if a scanning type exposure apparatus is configured by using the exposure light source of the present invention, the excimer laser used in the exposure light source may be a XeCl excimer laser even if there are a plurality of excimer lasers or even one. It is preferable to use them.

As a method for realizing the scanning exposure, for example, as shown in FIG. 2, a reticle driving mechanism 206a for horizontally moving the reticle 206 in a direction intersecting the optical axis of the exposure light L7. And a scan control unit 206b for controlling the reticle drive mechanism 206a to synchronize the horizontal movement of the stage 208 on which the wafer 209 is mounted, and relatively scans the reticle 206 and the wafer 209 in the horizontal direction. By performing the pattern transfer with the exposure light L7, it is possible to realize the scanning exposure.

(Embodiment 5) Next, an exposure light source according to a third embodiment of the present invention will be described with reference to FIGS. The exposure light source according to the third embodiment has substantially the same effects as the exposure light source according to the second embodiment illustrated in FIGS. 4 and 5, but has a different device configuration.

FIG. 6 is a conceptual diagram showing an example of a configuration of an exposure light source according to a third embodiment of the present invention, and FIG. 7 is a conceptual diagram showing an example of a configuration of a laser amplifier constituting a part thereof. FIG.

Two XeCl excimer laser 501a and XeCl excimer laser 501b are used as excitation light sources for the dye laser which is a component of the exposure light source 500 shown in FIG.
Is used. Both of them operate at a repetition rate of 500 Hz, but their oscillation timings are shifted by half the pulse interval. That is, as in the fourth embodiment, the two laser beams L53 and L54 combined by the mirror 502a and the half mirror 503 have a repetition rate of 1000 Hz. These laser beams L53 and L54 are provided by a half mirror 504,
Mirror 502c, mirror 502b, mirror 502
In both cases, the dye laser oscillator 5
05, used as excitation light for the first-stage dye laser amplifier 506a and the second-stage dye laser amplifier 506b. However, in the present embodiment, the dye laser oscillator 5
05, in the dye laser amplifiers 506a and 506b,
As shown in FIG.
5, the excitation light L56 and the excitation light L57 are supplied from one side of the dye cell 510, and are condensed in the dye solution 511 via the cylindrical lens 512, so that a single-side excitation method is used.

The dye laser oscillator 505 operated by the 1000 Hz excitation light oscillates at 1000 Hz. Similarly, the dye laser amplifiers 506a and 506b also amplify by the 1000 Hz excitation light. It is. Therefore, the exposure light L59, which is the second harmonic generated from the nonlinear optical crystal 507 on which the laser light L58 is incident, is also 1000H.
z.

In this embodiment, the dye laser oscillator 50
5. The dye laser amplifiers 506a and 506b are of a one-sided pumping type, but since there are a total of two or more dye cells 510 for irradiating the pumping lights L55, L56 and L57, a plurality of pumping lights can be used without leaving any excess. . This is a feature of the present invention using an excimer laser as an excitation light source. In addition, although the one-side excitation method is used, the part of the excitation light L55, L56, and L57 that irradiates the dye solution 511 that penetrates the dye solution 511 is reflected by the cylindrical concave mirror 513 and irradiates the dye solution 511 again. The utilization efficiency of the excitation light increases, and the efficiency of the dye laser increases.

(Embodiment 6) Next, an exposure light source according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a conceptual diagram showing an example of a configuration of an exposure light source according to a fourth embodiment of the present invention. That is, FIG.
Shows a configuration of a wavelength conversion dye laser 600 constituting an exposure light source according to the fourth embodiment.

In the wavelength conversion dye laser 600 of the fourth embodiment, a nonlinear optical crystal 605 is disposed inside a resonator, and a so-called internal wavelength conversion method is employed. In the internal wavelength conversion, only the wavelength-converted second harmonic is taken out of the resonator as exposure light L62, and the fundamental wave is confined inside the resonator. Therefore, the power of the fundamental wave inside the resonator increases, so that the wavelength becomes higher. It is known that there is a feature of high conversion efficiency. The wavelength conversion dye laser 600 of the present embodiment includes a total reflection mirror 601 and a total reflection concave mirror 6.
02 and a dichroic mirror 609 for extracting the second harmonic L62, a beam splitter 610, a dye cell 604, and four prisms inside the resonator. And a beam width converter 606 to be used. A part of the laser light generated in the resonator is taken out of the resonator by the beam splitter 610, and the diffraction grating 611 is formed.
Hit. This determines the oscillation wavelength. An etalon 612 for narrowing the wavelength width is also used.

In the wavelength conversion dye laser 600, a part of the laser light generated in the resonator is taken out of the resonator by the beam splitter 610, and
13 is incident. Thereby, the wavelength conversion dye laser 60
The wavelength of the fundamental wave oscillating at 0 is monitored. As a result, the oscillation wavelength is stabilized, and as a result, the wavelength of the exposure light L62, which is the second harmonic generated from the nonlinear optical crystal 605, is also stabilized. That is, although the wavelength conversion dye laser 600 of the present embodiment performs internal wavelength conversion, the wavelength splitter 6
By inserting 10, the fundamental wave in the resonator can be taken out of the resonator and its wavelength can be monitored.
Therefore, also in the present embodiment, the exposure light L6 in the vacuum ultraviolet region
Since the wavelength can be stabilized without directly monitoring the wavelength monitor 2, the life of the wavelength monitor 613 is extended.

Since the wavelength conversion dye laser 600 of the present invention is used particularly as an exposure light source, an average output that is higher by about one to two orders of magnitude than a general dye laser oscillator used for spectroscopy or the like is required. The width of the dye solution 603 flowing in the dye cell 604 is increased. Note that the dye solution 603 flows in a direction perpendicular to the paper surface. That is, with respect to the dye solution 603, the excitation light L61a and the excitation light L61b from the XeCl excimer laser pass through the cylindrical lens 607a and the cylindrical lens 607b that converge in only one direction, and are focused only in the direction perpendicular to the paper. The light is condensed linearly with respect to the dye solution 603.

In this embodiment, the dye cell 604 in which the dye solution flows is arranged at a position where the beam is expanded by the beam width converter 606, and the dye solution in which the excitation light L61a and the excitation light L61b are condensed. Is larger in volume. According to this, the output of the excitation light can be increased. That is, if the excitation light is condensed at one point in the dye solution by the convex lens, the temperature of the dye solution may rise rapidly or the dye cell may be damaged. In addition,
In a conventional general dye laser oscillator, in order to increase the volume of the dye solution to be excited, as in the conventional dye laser oscillator 900 shown in FIG. 14, the dye solution 903 is moved along the optical axis direction of the laser beam. So that the dye cells 9
It was common to place 04. In the dye laser oscillator 900, 901 is an output mirror, 902 is a diffraction grating, 905 is a beam width converter, and 906 is excitation light L90.
Is a cylindrical lens for condensing light.

On the other hand, in the wavelength conversion dye laser 600 of the present invention, the length of the dye solution is shortened in the optical axis direction as shown in FIG. There is also an effect of stabilizing the wavelength. The oscillation wavelength of the dye laser oscillator slightly fluctuates due to a change in the resonator length. This is because the oscillation is performed so that the integral multiple of the wavelength of the oscillating light coincides with the cavity length. However, since the resonator length is exactly the optical path length in the resonator, when the refractive index of the medium in the resonator changes due to a temperature change, the optical path length changes due to the influence. The main substances through which the optical axis in the resonator passes are optical materials such as air, dye solutions, and prisms. Among them, the magnitude of the temperature coefficient of the refractive index in air is about 10 −6, and in the case of an optical material such as quartz, it is about 3 × 10 −6, whereas the optical material generally contains a dye solution. About 1
0 is the minus 4th power. That is, since the temperature coefficient of the refractive index of the liquid dye solution is orders of magnitude larger than that of air or optical materials, the effect of the temperature change on the optical path length is the largest due to the dye solution. Therefore, as in the present embodiment, when the length occupied by the dye solution 603 on the optical axis in the resonator is reduced, the dye solution 60
3, the influence of the temperature change is reduced.

That is, the oscillation wavelength changes in proportion to the ratio of the change in the optical path length caused by the change in the refractive index due to the temperature change to the resonator length.

As described above, in the wavelength conversion dye laser 600 according to the present embodiment, not only the excitation volume of the dye solution 603 is large and high output is possible, but also the length of the dye solution 603 occupying the optical axis is short. , High wavelength stability. This wavelength stability is particularly effective as exposure light. That is, when the wavelength of the exposure light changes, the refractive index of the reduction projection lens in the stepper changes, and as a result, the pattern projected on the wafer is blurred. Have been.

(Embodiment 7) Next, a modified example of the apparatus for converting the wavelength of the laser beam extracted from the dye laser in the exposure light source of the present invention by using a nonlinear optical crystal will be described in the fifth embodiment of the exposure light source of the present invention. It is exemplified as a form. That is, FIG. 9 shows a wavelength converter 700 in the exposure light source according to the fifth embodiment of the present invention.

When the laser beam L71 extracted from the XeCl excimer laser-excited dye laser in the exposure light source of the present invention (for example, the exposure light source 100 shown in FIG. 1) enters the wavelength conversion section 700, the cylindrical lens 701
And converges linearly in the nonlinear optical crystal 702 through the light. As a result, the wavelength is converted, and a laser beam L72 including ultraviolet light having a wavelength of 208 nm is generated. However, the laser beam L72 includes a second harmonic and a wavelength 416n which is an unconverted fundamental wave.
m laser light. The laser beam L72 including the unconverted fundamental wave is transmitted to the cylindrical concave mirror 703.
And is incident on the nonlinear optical crystal 702 again. As a result, the wavelength of the unconverted fundamental wave is converted, and the second harmonic is further generated. The second harmonic reflects the dichroic mirror 704 that reflects only the second harmonic, and the exposure light L7
3 is extracted from the wavelength conversion unit 700. As described above, in the wavelength conversion section 700, the laser light L
Since 71 passes twice through the nonlinear optical crystal 702, the ratio of the unconverted fundamental wave is low. That is, the wavelength conversion efficiency is higher than that of the normal wavelength converter 104 as shown in FIG. Further, the wavelength conversion efficiency is higher than that of the exposure light source that needs to generate the fifth harmonic as described above. For example, in the case of the third harmonic, after generating the second harmonic, it is necessary to combine the second harmonic with an unconverted fundamental wave to generate a sum frequency that is the third harmonic. This is because the harmonic is only generated by one wavelength conversion, and the unconverted fundamental wave cannot be used again for the generation of the second harmonic as in the present embodiment. Furthermore, since the exposure light L73 extracted from the wavelength conversion unit 700 of the present embodiment does not include an unconverted fundamental wave, there is no need to separate the fundamental wave when guiding the light to the stepper body.

(Embodiment 8) Next, referring to FIG. 12, FIG. 2 or FIG. 3 using the exposure light source of the present invention will be described.
An example of a method for manufacturing a semiconductor device using the exposure apparatus exemplified in FIG.

In FIG. 12, as an example of the step of performing photolithography, the silicon substrate 1 of the wafer 209 is used.
The case where a minute hole (contact hole 1002a) is formed in an insulating film 1002 of silicon dioxide (SiO ₂ ) deposited (deposited) on the surface of 001 is shown in the order of steps.

In the photolithography process, first, as illustrated in FIG.
A resist 1003 is applied to the insulating film 1002 deposited thereon.

Next, exposure is performed as shown in (2) (the one indicated by a number of arrows is exposure light L7 in FIG. 2). That is, the exposure light L7 having the pattern of the reticle 206 (FIG. 2) is applied to the resist 1003 on the wafer 209. Here, a contact hole 10 having a diameter ΔW
Exposure light L7 is not irradiated to a region corresponding to the position where 02a is to be formed.

In this embodiment, the resist 1003
Is called a negative resist. When developed after exposure, only the portions not irradiated with the exposure light L7 are selectively dissolved and removed in the developing solution as shown in FIG. A hole 1003a having a diameter ΔW is formed.

Then, as shown in FIG. 12D, when etching is performed, the insulating film 1002 exposed through the hole 1003a formed by removing the resist 1003 is removed by etching.

Finally, as shown in FIG. 12 (5), by removing the resist by ashing or the like, the insulating film 1002 having the contact hole 1002a having a diameter ΔW remains on the silicon substrate 1001.

In the present embodiment, the wavelength of the exposure light L7 is about 208 nm, so that even with ordinary exposure,
A hole with a minimum diameter of about 0.21 μm (contact hole 100
2a) and a line having a width of 0.21 μm can be processed. Further, when an ultra-high resolution technique such as a phase shift is used, a hole pattern or a line pattern having a diameter up to 0.13 μm, which is about 0.6 times the exposure wavelength, can be processed.
Therefore, in the method of manufacturing a semiconductor device of the present embodiment using the exposure apparatus of the present invention, the contact hole 1002a
This is effective when performing fine processing with a design rule of about 0.2 μm or less, such as gate processing and gate processing.

The technical effects of each embodiment of the above-described exposure light source, exposure method, exposure apparatus, and semiconductor device manufacturing method of the present invention are as follows.

In the exposure light source of the present invention, a KrF (or XeCl) excimer laser is used, so that the gas life is longer than that of an ArF excimer laser, and deterioration of a band-narrowing element and the like can be suppressed. Therefore, in the exposure apparatus using the exposure light source of the present invention, the running cost is lower than that of an ArF excimer laser stepper, and the throughput of the apparatus is also improved. Further, since the band can be sufficiently narrowed, the reduction projection lens can be constituted by a monochromatic lens.

Therefore, when the reduction projection lens is formed of a quartz lens in particular, if BBO is used as the nonlinear optical crystal, exposure light having a wavelength of 206 to 213 nm, which is slightly longer than that of the ArF excimer laser, can be generated.
The life of the reduction projection lens is extended, and a highly sensitive resist is not required. Since a reduction projection lens made of a quartz lens can be the same as a conventional projection lens, the exposure apparatus of the present invention can be realized at low cost. Therefore, in the exposure apparatus of the present invention, the throughput is improved and the exposure apparatus itself is inexpensive, so that a semiconductor integrated circuit can be manufactured in a short time and at low cost.

If a KrF excimer laser is used, a conventional KrF excimer laser using the laser light of the KrF excimer laser as the direct exposure light is used as the KrF excimer laser.
The KrF excimer laser of the F stepper can be used, and there is no need to purchase a new KrF excimer laser. As a result, the exposure apparatus of the present invention can be configured at low cost, and if it is used, a semiconductor integrated circuit can be manufactured at lower cost.

Also, unlike the stepper using the conventional excimer laser, the exposure light source of the present invention uses the excimer laser itself as the excitation light source of the dye laser oscillator without using the laser light from the excimer laser for direct exposure. There is no need to narrow the band, and the narrowing element is used in a dye laser oscillator. Therefore, as the band-narrowing element and the wavelength monitor, those which can be used at a wavelength of about 340 nm or more can be used, and almost no deterioration occurs. As a result, the running cost due to the replacement of the band-narrowing element and the wavelength monitor can be greatly reduced.

In particular, if a dye laser amplifier is also used, it is not necessary to increase the output of the dye laser oscillator so much, so that the intensity of the laser beam passing through the band-narrowing element used in the dye laser oscillator can be reduced. Thus, the band-narrowing element can be used for a long time.

Further, since the laser light whose wavelength is converted by the nonlinear optical crystal is oscillated by the dye laser oscillator, it is easy to oscillate in a single mode, so that the wavelength conversion efficiency can be easily increased. Further, in the present invention, since an exposure light having an arbitrary wavelength of about 170 nm or more can be obtained, it is possible to set the exposure light wavelength while avoiding the absorption peak wavelength of 180 to 200 nm of the chemically amplified resist composed of an aromatic compound. it can. Therefore, this resist can be used, and a new resist becomes unnecessary.
Further, KrF (or Xe) constituting the exposure light source of the present invention.
The laser light of the Cl) excimer laser has a relatively long wavelength even in the ultraviolet region and has good propagation characteristics in the atmosphere. Therefore, even if these excimer lasers alone are installed on the floor remote from the stepper body, the nonlinear optical crystal is placed near the stepper body, allowing efficient transmission of laser light without filling the long transmission path with nitrogen or the like. it can.

Further, by employing a configuration using a dye laser amplifier or a configuration in which excitation light is applied to the dye from two directions, a plurality of KrF (or XeCl) excimer lasers can be used, and these excimer lasers themselves can be used. Can be increased to an integral multiple without changing the configuration of Thereby, damage to the lens of the stepper can be suppressed. Furthermore, when used in a scanning type exposure apparatus, unevenness in the exposure amount can be reduced. In this case, it is particularly effective to use a XeCl excimer laser.

Further, in the wavelength conversion dye laser of the present invention, not only the volume of the dye container is large and high output is possible, but also the length of the dye solution occupying the optical axis is short and the wavelength stability is high. Therefore, the pattern projected on the wafer is not blurred.

The invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be variously modified without departing from the gist of the invention. Needless to say, there is.

For example, the application of the exposure light source of the present invention is not only required as an exposure light source of an exposure apparatus used for photolithography in a semiconductor device manufacturing process, but also requires a laser beam having a stable wavelength in a vacuum ultraviolet region. Can be widely applied to the field.

[0109]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

According to the exposure light source of the present invention, it is possible to overcome the above-mentioned various technical problems associated with the case where an ArF excimer laser is used as the exposure light source, and to achieve a wavelength of about 0.2 in the vacuum ultraviolet region.
The effect is obtained that the exposure light having a sufficient output in a micron and narrow band can be stably supplied for a long time.

Further, according to the exposure light source of the present invention, there is obtained an effect that deterioration of the band-narrowing element and the wavelength monitor can be suppressed, and the running cost due to the replacement can be reduced.

Further, according to the exposure light source of the present invention, there is obtained an effect that the absorption peak of a chemically amplified resist composed of a general aromatic compound can be avoided as the wavelength of the exposure light to be generated.

Further, according to the exposure light source of the present invention, an effect that a high repetition rate can be obtained without increasing the size of the apparatus can be obtained.

Further, according to the exposure light source of the present invention, the effect that the number of pulse repetitions can be increased without increasing the size of an apparatus using a large blower is obtained.

Further, according to the exposure method of the present invention, it is not necessary to fill the optical path for guiding the exposure light to the stepper body with nitrogen gas or the like, so that it is possible to simplify the equipment and reduce the cost.

Further, according to the exposure method of the present invention, an effect that a high throughput can be achieved is obtained.

Further, according to the exposure apparatus of the present invention, it is not necessary to fill the optical path for guiding the exposure light to the stepper body with nitrogen gas or the like, so that it is possible to simplify the equipment and reduce the cost.

Further, according to the exposure apparatus of the present invention, there is obtained an effect that a high throughput can be achieved.

Further, according to the method of manufacturing a semiconductor device of the present invention, there is obtained an effect that a semiconductor device having a design rule of a wavelength in a vacuum ultraviolet region can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an exposure light source according to the present invention.

FIG. 2 is a conceptual diagram illustrating an example of a configuration of an exposure apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing an example of an installation state of an exposure apparatus according to a second embodiment of the present invention in a clean room.

FIG. 4 is a conceptual diagram illustrating an example of a configuration of an exposure light source according to a second embodiment of the present invention.

FIG. 5 is a conceptual diagram showing an example of a configuration of a laser amplifier constituting a part of an exposure light source according to a second embodiment of the present invention.

FIG. 6 is a conceptual diagram illustrating an example of a configuration of an exposure light source according to a third embodiment of the present invention.

FIG. 7 is a conceptual diagram showing an example of a configuration of a laser amplifier constituting a part of an exposure light source according to a third embodiment of the present invention.

FIG. 8 is a conceptual diagram illustrating an example of a configuration of an exposure light source according to a fourth embodiment of the present invention.

FIG. 9 is a conceptual diagram illustrating an example of a configuration of a wavelength converter in an exposure light source according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing an example of characteristics of a normal resist made of an aromatic compound used in the exposure technique according to the embodiment of the present invention.

FIG. 11 is a conceptual diagram illustrating an example of scanning exposure in the exposure technique according to the embodiment of the present invention.

FIGS. 12A to 12C are cross-sectional views illustrating an example of a method for manufacturing a semiconductor device using an exposure apparatus employing the exposure light source of the present invention in the order of steps.

FIG. 13 is a diagram showing an example of characteristics of an alicyclic resist having an acrylic skeleton used in the exposure technique according to the embodiment of the present invention.

FIG. 14 is a conceptual diagram showing an example of a configuration of a conventional dye laser oscillator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Exposure light source 101 XeCl excimer laser 102 Dye laser oscillator 103 Dye laser amplifier 104 Wavelength conversion unit 105a Beam splitter 105b Beam splitter 106a Lens 106b Lens 106c Lens 106d Lens 107 Output mirror 108 Diffraction grating 109a Dye solution 109b Dye solution 110 Etalon 111 Nonlinear optical crystal 113 Wavelength monitor 150 Stepper body 200 Stepper 201a Mirror 201b Mirror 201c Mirror 202 Beam expander 203 Random phase plate 204 Fly-eye lens 205 Condenser lens 206 Reticle 206a Reticle drive mechanism 206b Scan controller 207 Reduction projection lens 208 Stage 209 Wafer 300 Stepper 301 'Floor 3 1a Floor 301b Floor 302 XeCl Excimer Laser 303 Wavelength Conversion Dye Laser 304a Mirror 304b Mirror 304c Mirror 304d Mirror 304e Mirror 305 Dye Laser Auxiliary Device 306 Flexible Tube 400 Exposure Light Source 401a XeCl Excimer Laser 401b XeCl Mirror 402b Mirror 402b Mirror 402b Mirror 402b Mirror 403 Half mirror 404a Half mirror 404b Half mirror 404c Half mirror 404d Half mirror 405 Dye laser oscillator 406a Dye laser amplifier 406b Dye laser amplifier 407 Nonlinear optical crystal 410 Dye cell 411 Dye solution 412a Cylindrical lens 412b Cylindrical lens 500 Exposure light source 501a XeCl excimer laser 501b XeCl excimer laser 502a mirror 502b mirror 502c mirror 502d mirror 503 half mirror 504 half mirror 505 dye laser oscillator 506a dye laser amplifier 506b dye laser amplifier 507 non-linear optical crystal 510 dye cell 520 Wavelength conversion dye laser 601 Total reflection mirror 602 Total reflection concave mirror 603 Dye solution 604 Dye cell 605 Nonlinear optical crystal 606 Beam width converter 607a Cylindrical lens 607b Cylindrical lens 608 Lens 609 Dichroic mirror 610 Beam splitter 611 Emission grating 612 Wavelength converter 701 Lindal lens 702 Nonlinear optical crystal 703 Cylindrical concave mirror 704 Dichroic mirror 900 Dye laser oscillator 901 Output mirror 902 Diffraction grating 903 Dye solution 904 Dye cell 905 Beam width converter 906 Cylindrical lens 1001 Silicon substrate 1002 Insulating film 1003a Contact hole 1003

Claims (10)

[Claims] 1. An excimer laser, a dye laser oscillator including a wavelength narrowing element, and a nonlinear optical crystal, wherein the dye laser oscillator performs laser operation using the excimer laser as an excitation light source. An exposure light source, which outputs a laser beam obtained by performing wavelength conversion of the extracted laser beam by the nonlinear optical crystal as exposure light. 2. The exposure light source according to claim 1, further comprising a plurality of KrF excimer lasers or XeCl excimer lasers as the excimer laser, wherein a plurality of the Kr excimer lasers are provided.
An rF excimer laser or the XeCl excimer laser is oscillated with a timing shifted from each other, and two of the plurality of laser lights extracted from the plurality of KrF excimer lasers or the XeCl excimer laser are subjected to the same half. The laser light is made incident on a mirror and includes a dye laser amplifier, or excitation light is applied to a dye as a laser medium in the dye laser oscillator.
An exposure light source characterized in that light is emitted from a direction. 3. The exposure light source according to claim 1, wherein the dye laser includes a nonlinear optical crystal and a beam width converter inside a resonator of the dye laser oscillator, and the dye solution as a laser medium of the dye laser oscillator includes: A first configuration disposed at a position where a beam width is expanded by a beam width converter, a second configuration including a wavelength monitor that monitors a wavelength of laser light extracted from the dye laser oscillator, the dye laser oscillator A third configuration including a nonlinear optical crystal and a beam splitter inside the resonator, and a wavelength monitor for monitoring a wavelength of laser light extracted from the beam splitter to the outside of the resonator; Has a fourth configuration in which the dichroic mirror and the total reflection mirror are arranged on the optical path so as to be interposed therebetween. , An exposure light source, characterized in that it comprises a fifth configuration, any configuration using an exposure KrF excimer laser is a laser operated without using the narrowing element wavelengths. 4. A laser operation of a dye laser oscillator including a wavelength narrowing element using an excimer laser as an excitation light source.
An exposure method, wherein a laser beam obtained by wavelength-converting a laser beam obtained from the dye laser oscillator using a nonlinear optical crystal is used as exposure light. 5. An exposure apparatus, comprising: an exposure light source for generating exposure light; and an exposure optical system for irradiating the exposure light to an object to be exposed via a reticle. An exposure apparatus comprising the exposure light source according to 2 or 3. 6. The exposure apparatus according to claim 5, wherein the exposure is performed by a scanning method in which the reticle and the object to be exposed are relatively scanned in a direction transverse to an optical axis of the exposure light. An exposure apparatus using an exposure light source. 7. The exposure apparatus according to claim 5, wherein, among the excimer laser and the nonlinear optical crystal constituting the exposure light source, the excimer laser is disposed in a clean room where the exposure apparatus is installed. An exposure apparatus, wherein the non-linear optical crystal is installed on a different floor from the exposure apparatus main body including the exposure optical system, and the nonlinear optical crystal is installed on the same floor as the exposure apparatus main body. 8. The exposure apparatus according to claim 5, wherein a β-BaB ₂ O ₄ crystal is used as the nonlinear optical crystal, and the reduction projection lens constituting the exposure optical system is a monochromatic lens made of a quartz lens. And the exposure light has a wavelength of 206.
A first configuration in which ultraviolet light of up to 213 nm is used, the reduction projection lens forming the exposure optical system is a monochromatic lens made of a fluorite lens, and the exposure light has a wavelength of 180 nm.
2. An exposure apparatus, comprising: any one of the following configurations: ultraviolet light of m or less. 9. A method of manufacturing a semiconductor device by photolithography in which a reticle pattern is transferred to a semiconductor wafer via exposure light, wherein the photolithography includes the exposure method according to claim 4, or A method for manufacturing a semiconductor device, comprising using the exposure apparatus according to claim 5. 10. The method of manufacturing a semiconductor device according to claim 9, wherein a chemically amplified resist made of an aromatic compound or an alicyclic resist is used for the photolithography, and the design rule of the semiconductor device is 0.12. 9. The exposure apparatus according to claim 8, wherein the first distance is 0.21 μm.
9. The exposure apparatus according to claim 8, wherein the design rule of the semiconductor device is 0.10 to 0.18 μm.
A method for manufacturing a semiconductor device, comprising using the configuration described in (1).