JPH0982605A - Scanning illumination device and scanning exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evenly illuminate a substrate to enable lithographic transfer with a high resolution by providing driving means for moving secondary light source forming means relative to an optical axis in synchronism with light emission from a pulse light source. SOLUTION: A light beam emitted from a coherent light source 1 such as an excimer laser passes through a beam shaping optical system and a light quantity adjusting means 3 and then through an optical integrator 5 (secondary light source forming means) such as a fly-eye lens for providing a uniform illuminance. The optical integrator 5 and a vibration applying means 20 form a uniform-illuminance applying means 4. The light beams further pass through an optical system 6, a variable aperture 8 and an optical system 9 and through a mask 13 reflected by a partial transmission mirror 10 and a projection optical system 14, and then illuminate a substrate 16. When the uniform-illuminance applying means 4 is actuated so that the substrate 16 has a uniform intensity distribution, uniform illumination can be achieved on the substrate 16 as balanced in its scanning direction and vertical direction and lithographic transfer of a transfer pattern can be realized with a high resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning illumination device, and more particularly to a scanning illumination device used in a scanning type exposure apparatus having a coherent light source.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor element or the like is manufactured by using a photolithography technique, a transfer pattern of a photomask (mask) is coated with a photoresist or the like through a projection optical system, or a substrate such as a glass plate. 2. Description of the Related Art A projection exposure apparatus that exposes and transfers onto (hereinafter, simply referred to as a substrate) is used. In recent years, the chip pattern of one semiconductor element tends to increase in size, and a projection exposure apparatus is required to expose a transfer pattern having a larger area onto a substrate.

Further, as the integration and the miniaturization of semiconductor elements increase, the resolution of the projection optical system must be improved.

In order to respond to the former increase in the size of the transfer pattern, the transfer pattern having a large area is formed on the substrate by synchronously scanning the mask and the substrate with respect to a slit-shaped illumination area such as a rectangle or an arc. A so-called slit scan exposure type projection exposure apparatus that exposes light to the substrate has been developed.

In order to meet the latter requirement for higher resolution, a pulse laser such as an excimer laser is used as a light source in the far ultraviolet region in a projection exposure apparatus.

When the mask is illuminated with a light beam from a coherent light source such as an excimer laser, there arises a problem such as non-uniformity of illuminance distribution. This is due to the interference fringes formed by the light flux from the coherent light source, and various types of illumination systems have been conventionally proposed in order to eliminate the nonuniformity of the illuminance distribution due to the interference fringes.

[0007]

However, since the above-mentioned thing is not related to the scanning type exposure apparatus but is the illumination for the stationary substrate, it suffices to achieve a simple uniform illuminance on the substrate. Therefore, when the above-mentioned illumination system is used in the scanning type exposure apparatus, the scanning direction is a superposition of the illumination regions that are moved little by little with the passage of time, so that the uniformity is further improved, while the non-scanning direction is I won't. Therefore, there is a problem that the resolution cannot be increased because the illuminance uniformization state differs between the scanning direction and the non-scanning direction on the substrate.

Further, in the above-described slit scan exposure method, there is a method of adjusting the exposure amount due to the difference in the photosensitivity of the substrate and the like by adjusting the width of the slit and the scanning speed of the substrate. Then, the overlapping state of the illumination regions in the scanning direction of the substrate changes. As a result, there is a problem in that the illuminance uniformization state in the scanning direction on the substrate also changes, and the image quality of the transferred pattern also changes. This problem will be described with reference to FIGS.

FIG. 2 is a schematic diagram showing the irradiation state of pulsed light on the substrate when the number of pulses required for proper exposure is two. When the scanning speed of the substrate is v and the width of the illumination area is D, the oscillation frequency f of pulsed light emission can be expressed as f = 2v / D. Note that f is constant in FIGS. 2 to 6 to simplify the description.

The state of intensity distribution due to interference fringes in the illumination area is shown for each pulse light of the first to third pulses.
This illuminance distribution pattern (interference fringe cycle) is shown in FIGS.
It is assumed to be the same for all the pulsed lights inside.

Since pulsed light emission is performed during scanning of the substrate, the area on the substrate illuminated by each pulsed light is displaced every moment. Illuminated by superimposing these multiple pulsed lights,
An area on the substrate that has been irradiated with pulses sufficient to complete the exposure is called an irradiation completed area.

In FIG. 2, the high intensity of the first pulse and the high intensity of the second pulse are in the middle of each other, so that the illuminance uniformity is good.

FIG. 3 shows the case where the number of pulses required for proper exposure is three, the scanning speed of the substrate is 2/3 v, and the width of the illumination area is D. In the irradiation completed region, the strong dots of the plurality of pulsed lights overlap with each other, so that stronger interference fringes than in FIG. 2 are generated.

FIG. 4 shows a case where the number of pulses required for proper exposure is four, the scanning speed of the substrate is 1/2 v, and the width of the illumination area is D. The irradiation completed region has a better illuminance uniformity than the case of FIG.

FIG. 5 shows the case where the number of pulses required for proper exposure is four, the scanning speed of the substrate is v, and the width of the illumination area is 2D. The intensity distribution in the irradiation completed region is equal to that in FIG. 2 at the position of the stripe, but the intensity is doubled.

FIG. 6 shows a case where the number of pulses required for proper exposure is 6 and the scanning speed of the substrate is 2/3 v and the width of the illumination area is 2D. The intensity distribution in the irradiation completed area is the same as that in FIG. 3 at the position of the stripe, but the intensity is doubled.

By changing the scanning speed and the slit width of the substrate as described above, the illuminance distribution in the irradiation completed region on the substrate becomes various states. As a result, the image quality of the transfer pattern of the mask that is exposed and transferred is in various states.

In order to solve the above problems, the present invention provides
An object of the present invention is to provide a scanning illumination device and a scanning type exposure device capable of uniformly illuminating an object.

[0019]

In order to achieve the above object, the first invention of the present application is a coherent light source and a secondary light source forming means for forming a plurality of secondary light sources upon incidence of light emitted from the coherent light source. And a scanning type illuminating device for illuminating the object by relatively scanning the object with respect to the light emitted from the secondary light source forming means. It is characterized in that it has a driving means for moving it.

In the scanning illumination system according to the first aspect of the present invention, the coherent light source is a pulse light source, and it is desirable to drive the driving means in synchronization with the light emission of the pulse light source.

The second invention of the present application has a coherent light source and a secondary light source forming means for forming a plurality of secondary light sources on which light emitted from the coherent light source is incident, and is emitted from the secondary light source forming means. The mask on which the transfer pattern is formed is illuminated by the generated light, and the transfer pattern is exposed and transferred onto the substrate by scanning the mask and the substrate relative to the light emitted from the secondary light source forming means. In the scanning exposure apparatus, the driving means for moving the secondary light source forming means is provided.

In the scanning type exposure apparatus of the second invention of the present application,
The coherent light source is a pulsed light source, and it is desirable to drive the driving means in synchronization with the light emission of the pulsed light source.

A third invention of the present application is a device manufacturing method characterized by manufacturing a device using the scanning exposure apparatus of the second invention of the present application.

[0024]

1 is a schematic view of a main part of a scanning type exposure apparatus to which the present invention is applied.

Coherent light source 1 such as excimer laser
The light beam emitted from is deformed into a desired light beam shape by the beam shaping optical system 2, passes through a light amount adjusting unit 3 that adjusts the light amount to a desired light amount, and an optical integrator 5 (such as a fly-eye lens) that makes the illuminance uniform. Secondary light source forming means). Reference numeral 20 denotes a vibrating means (driving means) for vibrating the optical integrator 5 in an arbitrary direction in a plane perpendicular to the optical axis of the illumination system, and the optical integrator 5 and the vibrating means 20 constitute the illuminance uniformizing means 4. ing. Further, after passing through an optical system 6, a variable diaphragm 8 for adjusting the width (slit width) of the illumination area in the scanning direction, and an optical system 9, the mask 13 and the projection optical system 1 are reflected by a partial transmission mirror 10.
Substrate 16 is irradiated via 4. With such a configuration, the pattern on the mask 13 is exposed and transferred onto the substrate 16.

Further, 7 is a driving means for the variable diaphragm 8, 11 is a light quantity detecting means composed of a light receiving element for detecting the quantity of the light flux transmitted through the partial transmission mirror, 12 is a driving means for the mask 13, and 15 is a substrate. 16 driving means.

When the illuminance equalizing means 4 is not operated,
As described above, due to the difference in the photosensitivity of the substrate 16, the substrate 1
When the scanning speed and the slit width of 6 are changed, the intensity distribution of the irradiation completed region is different, but by operating the illuminance uniformizing means 4 so that the intensity distribution on the substrate 16 is uniform, the intensity distribution on the substrate 16 is changed. It is possible to illuminate in a well-balanced and uniform manner in the scanning direction and the direction perpendicular thereto, and it is possible to perform exposure transfer of a transfer pattern with high resolution.

That is, when the intensity distribution in the scanning direction becomes substantially uniform due to the relationship between the scanning speed of the substrate 16 and the slit width, the optical integrator 5 is moved in the non-scanning direction by the vibrating means 20 in synchronization with the pulse oscillation. Vibrate. As a result, the interference fringes in the illumination area move in the non-scanning direction for each pulsed light, and the illuminance on the substrate 16 can be made uniform. On the other hand, when there is a problem in the illuminance uniformity in the scanning direction due to the relationship between the scanning speed of the substrate 16 and the slit width, as in the case where the points having high intensity of the pulsed light shown in FIGS. Need to move the interference fringes in the scanning direction. At this time, the vibration direction of the optical integrator 5 may be tilted from the non-scanning direction to the scanning direction according to the illuminance uniformity in the scanning direction. Regarding the degree of this inclination, confirm the angle at which the illuminance is made uniform by experiments in advance. Also, the optical integrator 5 may be vibrated two-dimensionally.

In this way, if the optical integrator 5 is slightly moved by the vibrating means 20, the substrate 1
It is possible to freely move the interference fringes or the like in the illumination area irradiated on the surface 6. Therefore, by controlling the moving direction and the position of the optical integrator 5 in synchronization with the pulse oscillation of the pulsed light, substantially uniform illumination in the scanning direction and the non-scanning direction on the substrate 16 becomes possible.

Next, an embodiment of a method of manufacturing a semiconductor device using the scanning type exposure apparatus of FIG. 1 will be described.

FIG. 7 shows a manufacturing flow of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels and CCDs). In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask production), a mask (mask 13) on which the designed circuit pattern is formed is produced. On the other hand, in step 3 (wafer manufacturing), a wafer (substrate 16) is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next Step 5
(Assembly) is called a post-process, and is a process of forming a chip using the wafer created in step 4, and includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. Step 6
In (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 8 shows a detailed flow of the wafer process. Wafer (substrate 16) in step 11 (oxidation)
Oxidizes the surface of the Step 12 (CVD) forms an insulating film on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted on the wafer. In step 15 (resist processing), a resist (sensitive material) is applied to the wafer. In step 16 (exposure), the scanning exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (mask 13). Step 17 (development)
Then, the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

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

[0034]

As described above, when the scanning illumination device of the present invention is applied to the scanning type exposure device, the substrate (object) can be uniformly illuminated and high resolution exposure transfer can be performed.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a scanning exposure apparatus to which the present invention has been applied.

FIG. 2 is a diagram showing a difference in illuminance distribution in an irradiation completion region of a mask due to changes in a slit width and a scanning speed of the mask.

FIG. 3 is a diagram showing a difference in illuminance distribution in an irradiation completion region of a mask due to changes in a slit width and a scanning speed of the mask.

FIG. 4 is a diagram showing a difference in illuminance distribution in an irradiation completion area of a mask due to changes in a slit width and a scanning speed of the mask.

FIG. 5 is a diagram showing a difference in illuminance distribution in an irradiation completion area of a mask due to changes in a slit width and a scanning speed of the mask.

FIG. 6 is a diagram showing a difference in illuminance distribution in an irradiation completion area of a mask due to changes in a slit width and a scanning speed of the mask.

FIG. 7 is a diagram showing a manufacturing process of a semiconductor device.

FIG. 8 is a diagram showing details of a wafer process during the step of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 beam shaping optical system 3 light quantity adjusting means 4 illuminance homogenizing means 5 optical integrators 6, 9 optical systems 7, 12, 15 driving means 8 variable aperture 10 partial transmission mirror 11 light receiving means 13 mask 14 projection optical system 16 substrate 20 Excitation means

Claims (5)

[Claims] 1. A light emitted from an object by the coherent light source and a secondary light source forming means for forming a plurality of secondary light sources into which light emitted from the coherent light source is incident. A scanning illuminating device for illuminating the object by scanning relative to the scanning illuminating device, comprising drive means for moving the secondary light source forming means with respect to an optical axis. 2. The scanning illumination device according to claim 1, wherein the coherent light source is a pulse light source, and the driving means is driven in synchronization with light emission of the pulse light source. 3. A coherent light source and a secondary light source forming means for forming a plurality of secondary light sources into which light emitted from the coherent light source is incident, and transfer by the light emitted from the secondary light source forming means. Illuminates the patterned mask,
A scanning type exposure apparatus for exposing and transferring the transfer pattern onto the substrate by scanning the mask and the substrate relative to the light emitted from the secondary light source forming unit, A scanning type exposure apparatus having a driving unit for moving the scanning type exposure apparatus. 4. The scanning exposure apparatus according to claim 3, wherein the coherent light source is a pulse light source, and the driving means is driven in synchronization with the light emission of the pulse light source. 5. A device manufacturing method comprising manufacturing a device using the scanning exposure apparatus according to claim 3.