JPS61220428A - Exposure device - Google Patents

Abstract

PURPOSE:To obtain a photo-resist pattern with high dimensional accuracy and alignment accuracy by a method wherein a face of a wafer base is designated to be low refractive index for exposure light or alignment light and/or both thereof. CONSTITUTION:A photo-resist 22 is applied to an Si film 22 on a quartz plate 21. When a wafer is adsorbed on a stand, where a color glass filter 24 absorbing exposure wavelength and alignment wavelength is fixed, and exposure and development are performed, a favorable pattern 23' is formed like a mask without reflected light from the base. When an Si pattern 22' is made by etching and CVD SiO2 26 and a photo-resist 27 are rotated and applied, then alignment of the mask is performed by designating the pattern 22' as the alignment target, and exposure development is performed using the same base, a favorable defective signal is obtained and alignment accuracy and dimensional accuracy are high, since there is no reflected light from the base. If refraction index of the color glass filter is approximated to that of the quartz plate thereof and reflection of the substrate-color glass filter interface are lessened, that is effective to decrease of reflection from the base.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a microfabrication method using photolithography in the production of semiconductor elements, magnetic bubble elements, etc., and relates to an exposure apparatus that forms patterns with high precision.

[Background of the invention]

In recent years, the scale of semiconductor integrated circuits has increased, requiring higher density and finer patterns. In conventional silicon substrates, as miniaturization progresses, the tolerance to abnormal current passing through the silicon portion of the substrate becomes significantly smaller. One solution to this problem is to form the device on a highly insulating substrate such as a quartz plate or sapphire. Furthermore, α-ray damage can be improved by using a highly insulating substrate. However, since quartz plates and sapphire transmit exposure light and pattern alignment detection light, these substrates have the problem that reflected light from the substrate/wafer support interface returns to the resist, causing a decrease in pattern dimensional accuracy and pattern alignment accuracy. There is. In other words, the substrate/
Exposure light or pattern detection light causes halation at the interface of the wafer support table, deteriorating the pattern shape or introducing noise into the pattern detection light. In particular, the reflected light from the edge of the wafer suction hole has a large degree of pattern shape deterioration and detection light noise due to its reflection angle, and when monochromatic light is used for each exposure, the reflected light from the substrate/wafer support interface The reflected light causes optical interference within the resist film, resulting in lower resolution and lower dimensional accuracy. Similarly, when monochromatic light is used as pattern detection light, light interference occurs within the resist film, and the pattern detection signal deteriorates.

The problem caused by the reflected light from the wafer support has not been recognized because devices with fine patterns have conventionally been made using opaque substrates such as silicon substrates. An invention related to a wafer support table is disclosed in, for example, Japanese Patent Laid-Open No. 134848/1983.

Most of the inventions are related to wafer adsorption, as shown in Japanese Patent Application Laid-Open No. 135742/1982, and no inventions have focused on reflected light.

Extended Abstracts on the Sixteenth (1984 International) reports on forming an electric circuit using a transparent quartz plate as a substrate.
Conference on Solid State Departments and Materials (1984) (Ext.
Ended Abstracts of the 16
th (1984 International) C
onference on 5solidState D
avices and materials (19
1984)) Kobayashi and Hogu, “MOSFET Characteristics on Connected Silicon Icing”, pp. 523-526.
Fused Silica (MOSFET Character
ri-stics of Connected
5ilicn l5lands on Fuse
There is a report titled ``dSilica)''.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure apparatus capable of forming a pattern with high dimensional accuracy and alignment accuracy on a substrate through which exposure light or alignment pattern detection light passes.

[Summary of the invention]

Since the above problem occurs due to the reflected light from the substrate/wafer support interface, the wafer support is made to be a light absorption surface for the exposure and pattern detection light.

Also as a light absorption surface, when the difference in refractive index between the substrate and the wafer support is large, the reflectance increases with the difference in refractive index, so the difference in refractive index is also made small. Since reflection at the wafer suction hole is particularly problematic, the wafer suction hole is formed in the light absorption layer on the wafer support at an angle to the incident light to reduce the problem of reflection.

[Embodiments of the invention]

The present invention will be explained below using examples. The exposure method may be a reduction projection exposure method, a 1:1 projection exposure method, or a contact exposure method. In this embodiment, a case where a reduction projection exposure method is used will be described.

1) First, as shown in FIG. 1, a color glass filter 2 is fixed on a wafer support stand 1 (wafer stage) of an exposure device.The six-color glass filter 2 has the exposure wavelength 43 of the exposure device.
An R-62 color glass filter was used that absorbs light at wavelengths of 6 nm, alignment wavelengths of 546 nm, and 577 nm. The thickness is approximately 1c. The filter is not limited to this type of colored glass filter, but may be used as long as it absorbs the exposure wavelength and the alignment wavelength, and the film thickness does not need to be 1 cIIl.

A hole 3 (hereinafter referred to as an adsorption hole) for adsorbing wafers was made in the colored glass filter 2. This suction hole was formed obliquely with respect to the optical axis direction.

As a result, there was no reflected light from the stainless steel wafer support located below the colored glass filter.

As shown in FIG. 2(a), a silicon film 22 with a thickness of about 0.5 μm is formed on a quartz plate 21 with a thickness of about 0.5 mm,
Furthermore, a photoresist film 23 (M
P1300 (manufactured by Microporosit) with a thickness of about 1 μm. Thereafter, as shown in FIG. 2(b), the wafer was placed on a wafer support 24 on which the colored glasses and filters were set, and exposure was performed. After that, normal development was performed. In this method, in which a colored glass filter was installed on the wafer support, there was almost no reflected light from the wafer support, and a good pattern 23' in accordance with the mask pattern could be formed on the substrate. Film thickness 0.5
The quartz plate and silicon film with a thickness of 0.5 μm in No. 1 transmit light with wavelengths of 436 nm, 546 nmw, and 577 nm. Therefore, when exposure is performed using a conventional method without a colored glass filter, pattern dimensional accuracy decreases due to light reflected from the wafer support, and in particular, halation occurs due to light reflected from the wafer suction hole, causing the resist pattern to be formed to be Even the phenomenon of disappearance occurred.

Next, the silicon film is processed using the resist mask 23' as an etching mask, and then the resist mask 23' is etched.
' was removed to form a pattern 22' made of silicon film as shown in FIG. 2(d). Then cylinder 2(e)
As shown in the figure, CVD (chemical vapor deposition)
About 0.5 pm of silicon oxide 11i26 was formed using the calVapour deposition method. Thereafter, a film 27 of photoresist 1 having a thickness of approximately 1 μm was formed on silicon oxide film 26 by spin coating. Mask alignment was performed using a pattern 22' formed on the silicon film as an alignment target, exposure was performed again, and then the phenomenon was performed. Since there was almost no reflected light from the wafer support, a good alignment detection signal was obtained, and therefore the alignment accuracy was also high. Furthermore, the pattern dimensional accuracy was also high. In this example, CVD silicon oxide film 0.5 μm/silicon go, s μm/quartz plate 0.5 μm/silicon go.
A substrate consisting of 5.5cm thick was used, but the film thickness is not limited to this, and the material also includes thermally oxidized silicon, polysilicon, PSG (
phosphor glass), polyimide, silicon nitride, tantalum oxide, tatin oxide.

Using a colored glass filter on the wafer support is effective when using a material that transmits exposure light, alignment light, or both, such as sapphire, soda glass, and gadolinium gallium garnet. In addition, in the examples, M P 1300 was used as the photoresist, but the photoresist is not limited to this.For example, 0FPR800 (manufactured by Tokyo Ohka Co., Ltd.)
A positive type resist such as HPR204 (Hunt) or a negative type resist such as 0MR85 (Tokyo Ohka Co., Ltd.) may be used, and the film thickness may be 1 μm.
Not limited to m.

Colored glass filters not only absorb exposure light and alignment light, but also have a small refractive index difference between the refractive index of a quartz plate, approximately 1.45, and the refractive index of sapphire, approximately 1.77 (the refractive index of a colored glass filter is (approximately 1.53), there was little reflection at the interface between these substrates and the colored glass filter, so it was particularly effective in reducing reflection from the wafer support.

2) Carbon was coated on the wafer support of the exposure apparatus to form a low reflection surface. Carbon coating was applied as a low reflection coating.

Dyes that absorb exposure and/or aligner light 1 For example, coumarin, oil yellow, and Olaosol F for 436 nm light.
ast Yellow) G CN, Curcumin e Rhodamine B for 546 nm light.

It may be coated with erythrosin or the like.

As in Example 1, a silicon film with a thickness of 0.5 μm was formed on a quartz plate with a film thickness of 0.5 mm, and a photoresist was applied, followed by exposure and development to form a pattern. As in Example 1, a highly accurate pattern could be formed. Further, when a pattern was formed on a silicon film and a silicon oxide film was formed on the pattern in the same way as in Example 1, a good alignment detection signal was obtained and the alignment accuracy was also high.

When a dye such as Rhodamine B was coated on a wafer support, the dye peeled off and caused contamination. In this case, by installing a quartz plate on a wafer support with low reflection, peeling of the dye could be prevented and contamination could be prevented.

In addition, to prevent peeling, a ladder-type silicone film, which is a surface-strengthening film, was formed on the wafer support with low reflection.

In this case too, contamination could be prevented.

3) The upper surface of the wafer support of the exposure apparatus was roughened, and mask alignment and pattern formation were performed in the same manner as in Examples 1 and 2. Due to the rough surface finish, light was diffusely reflected within the rough surface of the upper part of the wafer support, and light absorption inside the rough surface was increased. Therefore, the amount of light reflected onto the substrate was reduced, allowing highly accurate mask alignment and pattern formation.

〔Effect of the invention〕

According to the present invention, a photoresist pattern with high dimensional accuracy and alignment accuracy can be formed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the main parts of the apparatus of the present invention, and FIG. 2 is a process diagram showing one embodiment of the present invention. 1... Wafer support stand, 2... Colored glass filter,
3... Wafer suction hole, 21... Quartz plate, 22...
・Silicon film, 22'...Silicon pattern, 23・
...Photoresist, 23'...Photoresist pattern. 24... Wafer support stand, 25... Mask, 26...
...Silicon oxide film, 27...Photoresist, 27
′...Photoresist pattern.

Claims (1)

[Claims] 1. In an exposure apparatus having at least one of an exposure optical system and/or an alignment optical system, a light source, a mask, and a wafer support, the surface of the wafer support is illuminated with exposure light, alignment light, or both. An exposure device characterized by having a surface with low reflection for light. 2. The exposure apparatus according to claim 1, wherein the low light reflection layer of the wafer support is made of colored glass. 3. The exposure apparatus according to claim 1, further comprising a surface protective film on the low light reflection layer of the wafer support. 4. An exposure apparatus according to claim 3, wherein the surface protective film is made of a quartz plate or a silicone film. 5. According to claim 1, the wafer support has a wafer suction hole in the low light reflection layer that is inclined with respect to the optical axis of the exposure light, the alignment light, or both. Exposure equipment. 6. The exposure apparatus according to claim 1, wherein the upper surface of the wafer support is a rough surface.