JPH09213618A - Projection exposure apparatus and device manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a projection exposure apparatus capable of projecting and exposing a circuit pattern on a reticle surface onto a wafer surface with high accuracy, and a device manufacturing method using the same. SOLUTION: When a pattern on a mask surface illuminated by an illumination light flux from an illumination system is projected and exposed on a photosensitive substrate surface by a projection optical system, the illumination system includes a light shielding means for shielding an illumination central portion of the illumination light flux. The projection optical system has a reflection optical system including an optical member having a light-shielding portion or / and an opening in the exposure central portion so that the exposure central portion of the exposure light beam does not contribute to image formation. The member is located on the pupil plane of the projection optical system, and the optical member and the light shielding means are set so as to have an optically conjugate relationship.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and a method of manufacturing a device using the projection exposure apparatus.
In a so-called stepper, which is an apparatus for manufacturing various devices such as SI, CCD, liquid crystal panel, and magnetic head, a circuit on an original plate (hereinafter referred to as a “mask”) such as a photomask or a reticle illuminated with exposure light from a light source means. This is suitable for manufacturing a device by projecting and transferring a pattern onto a wafer surface coated with a photosensitive agent.

[0002]

2. Description of the Related Art In recent semiconductor device manufacturing techniques, various attempts have been made to change the exposure wavelength from g-line to i-line (wavelength: 365 nm) to improve the resolution by an exposure method using an ultra-high pressure mercury lamp. I have.

Also, a KrF excimer laser (wavelength 248n
m) or ArF excimer laser (wavelength 193 nm) and other various methods for improving the resolution by using pulsed light with a short wavelength from an excimer laser.

An equal-magnification exposure device (mirror projection aligner) that exposes a mask and a photosensitive substrate at once by scanning with a mirror optical system of equal magnification having an arc-shaped exposure area
Also, various reduction projection exposure apparatuses (steppers) have been proposed in which a pattern image of a mask is formed on a photosensitive substrate by a refractive optical system and the photosensitive substrate is exposed by a step-and-repeat method.

As a stepper, a step-and-scan type stepper has recently been proposed which can obtain a high resolution and can enlarge the screen size. This step-and-scan type scanning exposure apparatus is, for example, “0 p
lus E "(February 1993, pages 96-99).

This scanning exposure apparatus has a slit-shaped exposure area, and the exposure of a shot is performed by scanning the slit. When the scanning exposure of one shot is completed, the wafer steps to the next shot and the exposure of the next shot is started. This is repeated to expose the entire wafer.

In addition to this, by changing the illumination method on the mask surface, that is, by changing variously the light intensity distribution (effective light source distribution) formed on the pupil surface of the projection optical system, the resolution is further improved. An exposure method with improved performance and a projection exposure apparatus using the same have been proposed, for example, in JP-A-6-302502 and JP-A-7-78753.

On the other hand, many projection optical systems called catadioptric systems which combine a refraction system (lens) and a reflection system (mirror) have been proposed. The catadioptric projection optical system has the advantage of producing less chromatic aberration than the projection optical system composed of only lenses, making the most of the features of the mirror.

[0009]

Since the excimer laser light has a very short wavelength, many ordinary optical glasses have low transmittance and cannot be used as a material for a projection lens system. As an optical glass that can be used when using an excimer laser beam, quartz (SiO 2) is currently used in terms of transmittance.
₂ ) and fluorspar (CaF ₂ ). However, fluorite has a problem that the material is soft and difficult to process. Therefore,
Currently, quartz is the only practical lens material that can be used. Therefore, the projection lens system for a projection exposure apparatus using an excimer laser as a light source needs to be composed of only quartz, that is, a single glass material.

Generally, only a single glass material can be used, which makes it difficult to correct chromatic aberration in terms of lens design. Therefore, in order to secure a desired resolution, it is necessary to narrow the wavelength band of the light emitted from the excimer laser light source to the extent that it is not necessary to correct chromatic aberration. However, due to the principle of the excimer laser, narrowing the band reduces the laser output and makes it more difficult to oscillate stably. Also, the cost will increase significantly.

When the output of the light source in the projection exposure apparatus decreases, the throughput decreases. Therefore, when using an excimer laser, it is necessary to avoid narrowing the band as much as possible, which causes a contradiction with the problem of chromatic aberration. There is.

The present invention is a glass material that can be used as a projection optical system by appropriately setting the configurations of the illumination system and the projection optical system when the mask surface pattern is projected and exposed on the photosensitive substrate surface through the projection optical system. Even if the number is limited, chromatic aberration can be satisfactorily corrected without narrowing the band of the excimer laser, and the pattern on the mask surface can be easily exposed and transferred onto the wafer surface with high resolution. A projection exposure apparatus and a device manufacturing method using the same are provided.

[0013]

The projection exposure apparatus of the present invention is (1-1) when a pattern on a mask surface illuminated by an illumination light flux from an illumination system is projected and exposed on a photosensitive substrate surface by a projection optical system. The illumination system has a light blocking means for blocking the illumination central portion of the illumination light beam, and the projection optical system has a light blocking portion or / and a light exposure central portion of the exposure light beam so as not to contribute to image formation. A reflection optical system including an optical member provided with an opening is provided, the optical member is located on a pupil plane of the projection optical system, and the optical member and the light shielding unit are set to have an optically conjugate relationship. It is characterized by doing.

In particular, (1-1-1) the central illumination portion and the central exposure portion are in an optically conjugate relationship.

(1-1-2) The reflection optical system has a concave reflection member having an opening at the center of the exposure, and the optical member has a reflection / light-shielding portion at the center of the exposure. The light fluxes from the above are sequentially transmitted through the peripheral portion of the optical member, reflected by the concave reflection member, reflected by the reflection / light-shielding portion of the optical member, and then emitted from the opening of the concave reflection member.

(1-1-3) The reflecting optical system has a concave reflecting member, and the optical member has an opening in the central portion of the exposure and a reflecting surface in the peripheral portion thereof, and the luminous flux from the illumination system. Are sequentially reflected by the reflecting surface of the optical member, reflected by the concave reflecting member, and then emitted from the opening of the optical member.

(1-1-4) The mask or / and the photosensitive substrate are scanned in a direction perpendicular to the optical axis of the projection optical system so that the pattern on the mask surface is scanned and exposed on the photosensitive substrate. To be.

(1-1-5) The mask and the photosensitive substrate are synchronously scanned in a direction perpendicular to the optical axis of the projection optical system at a speed ratio corresponding to the projection magnification of the projection optical system, The pattern on the mask surface is scanned and exposed on the photosensitive substrate. And so on.

The device manufacturing method of the present invention is characterized in that the device is manufactured by using the projection exposure apparatus having the constitutional requirement (1-1).

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. In the figure, 1 is a light source such as a mercury lamp or an excimer laser. Reference numeral 2 denotes an illumination optical system including a beam compressor and the like, which shapes the light beam from the light source 1 into a predetermined beam shape and makes it incident on a light incident surface 3a of a homogenizer (optical integrator) 3.

The homogenizer 3 is composed of a plurality of minute lenses arranged two-dimensionally, and a plurality of secondary light sources are formed in the vicinity of the light emitting surface 3b. Reference numeral 4 denotes a light shielding plate (light shielding means), and a secondary light source formed near the light emitting surface 3b of the homogenizer 3 in the central portion (illumination central portion) serves as modified illumination such as annular illumination or quadrupole illumination. An opening 4a is provided for this purpose.

Reference numeral 5 denotes a condenser lens, which collects the light flux that has passed through the opening 4a of the light shielding plate 4 and illuminates the mask (reticle) 6. The mask (first object) 6 has a circuit pattern formed thereon and is held by the mask stage 7. Reference numeral 8 is a lens system, and 9 is a reflection optical system, which has two reflection members (optical members) 9a and 9b. In the reflecting member 9a, the peripheral portion 9a1 is formed of a flat surface or a transmitting surface having a refractive power, and the central portion (exposure central portion) is formed of a flat surface or a reflecting surface having a refractive power (reflection shading portion) 9a2. The peripheral portion of the reflecting member 9b is a concave mirror (spherical or aspherical).
And the central portion is formed of an opening for passing a light beam. Reference numerals 10 and 11 are lens systems.

In this embodiment, the illumination optical system 2, the homogenizer 3, the light shielding plate 4 and the condenser lens 5 constitute one element of the illumination system. Further, in the present embodiment, each of the elements 8, 9, 10 and 11 constitutes one element of the projection optical system, and the circuit pattern on the surface of the mask 6 will be described later.
It is projected on the two surfaces at a predetermined magnification. A photosensitive substrate 12 such as a wafer is coated with a resist on its surface. A photosensitive substrate stage 13 holds the photosensitive substrate 12 and drives it in the X, Y, and Z directions.

In the present embodiment, the secondary light source for illuminating the mask 6 is a central light-shielding modified illumination such as an annular light using the light-shielding plate 6, and at least one central light-shielding reflecting member 9a is provided in the projection optical system. The light-shielding portion 9a2 and the light-shielding portion 4b such as the modified illumination system are provided in a conjugate relationship so that the central light-shielding portion is not exposed to the light flux. As a result, the correction of the chromatic aberration of the projection optical system and the improvement of the resolution are simultaneously achieved.

Next, the features of each element in this embodiment will be described. In FIG. 1, the light flux from the light source 1 is converted into a light flux optimum for exposure by the illumination optical system 2. This light flux is once condensed before the homogenizer 3 and passed through the homogenizer 3 to make the intensity distribution uniform. The exit surface 3b of the homogenizer 3 has a finite size determined by the opening 4a of the light shielding plate 4 with a uniform intensity distribution.
It is designed so that it can be regarded as the next light source.

The light-shielding plate 4 has, for example, a ring-shaped opening 4a as shown in FIG. 2, and a light-shielding portion is formed on a transparent substrate such as a glass substrate by metal vapor deposition or the like so that light passes through the opening 4a. Four
b and 4c are provided. Central light-shielding portion 4b
The radius R1 and the radius R2 of the ring-shaped transparent portion 4a are selected to be optimum values according to the original image pattern line width in order to obtain a desired resolution.

In addition, in the present embodiment, the light-shielding portion 4 has openings 4e1 and 4e in quadrants 1, 2, 3, and 4 with the optical axis (center axis) 4d as the center, as shown in FIG.
It may be configured to provide so-called quadrupole illumination provided with 2, 4e3 and 4e4.

In the shading plate 4 shown in FIG. 3, radii R1 and R
For the sizes of 2 and the central band-shaped light shielding portions S1 and S2, optimum values are selected according to the original image pattern line width in order to obtain a desired resolution.

Returning to FIG. 1, a portion of the light shield plate 4 that passes through the opening 4a is used as a secondary light source, and light emitted from this arbitrary point is collimated by the condenser lens 5 and fixed to the mask stage 7 by vacuum suction or the like. The mask 6 having the obtained original image pattern information is illuminated, and an image is formed through the lens system 8 on the effective light source position Q where the optical member 9a is located.

The effective light source position Q substantially coincides with the position of the pupil plane of the projection optical system. At this time, the position P of the light blocking plate 4 of the illumination system and the effective light source position Q are in a conjugate relationship with each other, and the central light blocking portion 4b of the light blocking plate 4 is the optical member 9 formed by the reflective optical system 9.
Each element is set so as to have a conjugate relationship with the central light-shielding portion 9a2 of a.

The light flux having the original image pattern information of the mask 6 which has passed the effective light source position Q is reflected by the reflecting member 9b and the reflection / light-shielding portion 9b.
After being reflected by a2 and then converged and emitted from the opening of the reflection member 9b, an image is formed on the photosensitive substrate 12 which is vacuum-sucked to the photosensitive substrate stage 13 via the lens systems 10 and 11. As a result, the pattern on the mask 6 surface is formed on the photosensitive substrate 12
It is transferred and exposed.

In this embodiment, the light beam is converged by using the reflection optical system 9 including the concave reflection member 9b as a part of the projection optical system. Since chromatic aberration does not occur in principle in the reflective optical system, it is possible to efficiently correct chromatic aberration by converging the light flux by using the reflective optical system in a part of the projection optical system where the power is relatively large. I am trying.

Further, with the above-mentioned structure, even if the central portion is shielded by the reflective optical system 9, the original image pattern of the mask 6 can be formed at a high resolution due to the modified illumination effect.
It is possible to form an image.

In this embodiment, the mask stage 7
And the photosensitive substrate stage 13 is moved for each exposure transfer to expose the entire surface of the photosensitive substrate 12, but the mask stage 7 and the photosensitive substrate stage 13 are in a plane perpendicular to the optical axis of the projection optical system 9 during the exposure. It is also possible to adopt a configuration of scanning exposure in which the relative exposure is performed. It is also possible to adopt a configuration in which the mask stage 7 and the photosensitive substrate stage 13 are scanned in the directions parallel and perpendicular to the paper surface during exposure to perform two-dimensional scanning exposure.

FIG. 4 is a schematic view of the essential portions of Embodiment 2 of the present invention. The present embodiment is different from the first embodiment in FIG. 1 only in part of the optical members constituting the projection optical system,
The other elements are the same.

Next, the configuration of this embodiment will be described with reference to FIG.
The explanation will focus on the parts that are different from. 4 in FIG.
Reference numerals 1 and 43 are lens systems, 42 is a mirror, 44 is a mirror (optical member) having a hole 44a in the central portion (exposure central portion), and 45 is a reflecting member composed of a concave mirror.

In this embodiment, the light beam from the light source 1 is converted into a light beam optimum for exposure by the illumination optical system 2 and is condensed in front of the homogenizer 3. The exit surface 3b of the homogenizer 3 has a uniform intensity distribution and can be regarded as a secondary light source having a finite size determined by the opening 4a of the light shielding plate 4.

The light-shielding plate 4 has a ring-shaped opening 4a, and a portion passing through the opening 4a serves as a secondary light source. The light emitted from an arbitrary point of the secondary light source becomes parallel light by the condenser lens 5, and illuminates the mask 6 fixed to the mask stage 7.

The light flux having the original image pattern information of the mask 6 passes through the lens system 41, the mirror 42, the lens system 43, and the perforated mirror (optical member) 44 to form the concave reflection member 45.
The light is guided.

Then, the light flux converged by the concave reflecting member 45 is further imaged through the lens systems 10 and 11 onto the photosensitive substrate 12 which is vacuum-adsorbed on the photosensitive substrate stage 13, whereby transfer exposure is performed. There is. At this time, the sizes R and 44D of the central light shielding portion 4b and the central opening portion 44a are selected so that the central light shielding portion 4b of the light shielding plate 4 and the central opening portion 44a of the perforated mirror 44 have a substantially conjugate relationship.

In the first embodiment, the central portion is shielded from light, but in the present embodiment, the central portion of the mirror 44 is used as the opening 44a to allow the light flux to escape, and as a result, an effect equivalent to light shielding is obtained.

In this embodiment, as in the first embodiment shown in FIG. 1, the concave reflecting member 45 is given a large power (refractive power) to effectively correct chromatic aberration and combine it with modified illumination such as annular illumination. As a result, the circuit pattern on the mask 6 is imaged on the photosensitive substrate 12 with high resolution.

In the present embodiment, the mirror 42 and the lens system 43 may be omitted and the light flux from the lens system 41 may be guided to the perforated mirror 44.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described.

FIG. 5 shows a flow of manufacturing semiconductor devices (semiconductor chips such as IC and LSI, or liquid crystal panels, CCDs, etc.). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, an assembly process (dicing, bonding), a packaging process (chip encapsulation). Etc. are included.

In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 6 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated device which has been difficult to manufacture in the past.

[0053]

As described above, according to the present invention, when the pattern on the mask surface is projected and exposed on the surface of the photosensitive substrate through the projection optical system, the configuration of the illumination system and the projection optical system can be set appropriately. Therefore, even if the glass material that can be used as the projection optical system is limited, chromatic aberration can be corrected well without narrowing the band of the excimer laser, and the pattern on the mask surface can be highly resolved on the wafer surface. It is possible to achieve a projection exposure apparatus that can be easily exposed and transferred and a device manufacturing method using the same.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory view of the light shielding plate of FIG.

FIG. 3 is an explanatory view of the light shielding plate of FIG.

FIG. 4 is a schematic view of a main part of a second embodiment of the present invention.

FIG. 5 is a flowchart of a device manufacturing method of the present invention.

FIG. 6 is a flowchart of a device manufacturing method according to the present invention.

[Explanation of symbols]

 1 Light Source 2 Illumination Optical System 3 Homogenizer 4 Light-shielding Plate 5 Condenser Lens 6 Mask (Reticle) 7 Mask Stage 8, 10, 11 Lens System 9 Reflective Optical System 9a, 9b Reflective Optical Member 12 Photosensitive Substrate 13 Photosensitive Substrate Stage

Claims (7)

[Claims] 1. A shading means for shading an illumination center portion of the illumination light flux when the projection optical system projects and exposes a pattern on a mask surface illuminated by the illumination light flux from the illumination system onto a photosensitive substrate surface. The projection optical system has a reflection optical system including an optical member provided with a light-shielding portion or / and an opening in the exposure central portion so that the exposure central portion of the exposure light beam does not contribute to imaging. A projection exposure apparatus, wherein an optical member is located on a pupil plane of the projection optical system, and the optical member and the light shielding unit are set to have an optically conjugate relationship. 2. The projection exposure apparatus according to claim 1, wherein the illumination central portion and the exposure central portion are optically conjugate with each other. 3. The reflection optical system has a concave reflection member having an opening at the center of exposure, and the optical member has a reflection / light-shielding part at the center of exposure. 2. The light is transmitted through the peripheral portion of the optical member, reflected by the concave reflecting member, reflected by the reflective light shielding portion of the optical member, and then emitted from the opening of the concave reflecting member. Or the projection exposure apparatus of 2. 4. The reflective optical system has a concave reflecting member,
The optical member is provided with an opening in the central portion of the exposure and a reflecting surface in the peripheral portion, and the light flux from the illumination system is sequentially reflected by the reflecting surface of the optical member and then by the concave reflecting member. The projection exposure apparatus according to claim 1, wherein the projection exposure apparatus emits light through an opening of the optical member. 5. The mask or / and the photosensitive substrate are scanned in a direction perpendicular to the optical axis of the projection optical system to scan and expose the pattern on the mask surface onto the photosensitive substrate. The projection exposure apparatus according to claim 1, 2, 3, or 4. 6. The pattern on the mask surface is scanned by synchronizing the mask and the photosensitive substrate in a direction perpendicular to the optical axis of the projection optical system at a speed ratio corresponding to the projection magnification of the projection optical system. 5. The projection exposure apparatus according to claim 1, wherein the photosensitive substrate is scanned and exposed. 7. A device manufacturing method, wherein a device is manufactured using the projection exposure apparatus according to claim 1. Description: