JP2821394B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a semiconductor device capable of forming a pattern without being affected by a standing wave effect even in a portion having a different resist film thickness on a semiconductor substrate having a step. The present invention relates to a device manufacturing method.

[0002]

2. Description of the Related Art A plurality of patterns are formed in a manufacturing process of a semiconductor device. In this case, a photosensitive (photoresist) film applied on the surface of a semiconductor substrate is generally applied by using an optical reduction exposure apparatus called a stepper. A method of exposing and removing is used.

In the conventional pattern exposure method, as shown in FIG. 3, light 9A from a light source emitting a single wavelength light is irradiated on a mask composed of light shielding patterns 6A and 6B deposited on a quartz glass 5 and transmitted. Irradiates and exposes a photoresist film 4 (hereinafter simply referred to as a resist film) applied on a film such as a polysilicon film 3 formed on a silicon substrate 1 through an optical lens 7 for condensing and reducing the light. It is.

In the prior art, light 9A of a single wavelength emitted from a single light source inside a stepper is partially shielded or transmitted by the light shielding patterns 6A and 6B on the quartz glass 5, but is transmitted through the quartz glass 5. Only the emitted light is condensed and reduced by the optical system lens 7 inside the stepper, and the resist film 4 on the silicon substrate 1 is exposed. Since the resist film has the property of being divided into a portion that is exposed to and dissolved in a solvent and a portion that is not exposed and does not dissolve, the resist film that is soluble in the solvent is removed and the remaining resist film is used as a mask to form a polysilicon film to be etched. The film 3 is etched with a chemical or gas. By repeating this pattern formation, a pattern required for the semiconductor device is formed.

However, when exposing the resist film 4 on the silicon substrate on which the step 2 is formed, the interference between the light from the light source and the light reflected by the film on the silicon substrate changes due to the step on the silicon substrate. However, there is a disadvantage in that a standing wave effect such that the resist dimension becomes thicker or thinner partially occurs.
If the processing dimensions of the thick resist film 4A and the thin resist film 4B used as a mask vary due to the standing wave effect, the characteristics of a semiconductor device composed of thousands to millions of transistors are all reduced. The semiconductor device will not be configured as designed, and the designed electrical features of the semiconductor device will not be satisfied. For this reason, in the prior art, electrical characteristics are adjusted by repeating partial mask correction.

A method of exposing different patterns using the same mask without performing the mask correction is disclosed in
-80258. This method uses 1
A mask is used in which a plurality of evaporation patterns are formed on a piece of quartz glass, and an interference filter that transmits light of a specific wavelength is formed on the patterns. According to this method,
When the mask is irradiated with the first light having a specific single wavelength as exposure light, the first light transmits through only a portion of the pattern configured to correspond to the single wavelength. Only will be transcribed.

After that, when the mask is irradiated with second light having another single wavelength as exposure light, the second light transmits only another pattern portion configured to correspond to the single wavelength. Therefore, only that pattern is transferred this time.

In this manner, two or more types of patterns can be respectively transferred by one mask, so that the number of masks to be prepared in the process of transferring a plurality of types of patterns can be reduced.

[0009]

In manufacturing a semiconductor device, it is inevitable that a step is formed on a semiconductor substrate. This step causes a difference in the thickness of the resist film to be spin-coated. For this reason, the conventional technique has a problem that the size of the light-shielding pattern on the quartz glass must be changed according to the difference in the thickness of the resist film.

Further, even in the method disclosed in JP-A-63-80258, since the structure has a plurality of vapor deposition patterns,
In all of the plurality of patterns, it is necessary to change the pattern dimension according to the difference in the thickness of the resist film. Furthermore, in this method, an interference filter is used, but since a single wavelength light source that generates UV light is used as a light source, not only is it difficult to create a desired interference filter, but also a light source corresponding to the interference filter. Has to be used, so that the UV light source must be replaced for each pattern.

An object of the present invention is to provide a method of manufacturing a semiconductor device capable of forming a high-precision pattern on a photoresist film by eliminating the effect of a standing wave effect at the time of exposure.

[0012]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a photoresist film on a semiconductor substrate having a step formed thereon; and forming a pattern comprising a light shielding film on one surface of a quartz substrate. In a method for manufacturing a semiconductor device, a pattern is formed by exposing and developing a thick photoresist film and a thin photoresist film using a mask formed with
A first interference filter that transmits only light of a first wavelength is formed in a first area corresponding to the thick photoresist film on the other surface of the quartz substrate, and a second interference filter corresponding to the thin photoresist film is formed. It is characterized in that a mask having a second interference filter which transmits only light of the second wavelength in a region is used.

According to a second aspect of the invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a photoresist film on a semiconductor substrate having a step formed thereon, and exposing and developing the thick photoresist film and the thin photoresist film using a mask; In a method of manufacturing a semiconductor device for forming a pattern, a first interference filter that transmits only light of a first wavelength formed in a quartz substrate and a first region corresponding to the thick photoresist film on the quartz substrate And a second photoresist film corresponding to the thin photoresist film.
The second light transmitting only the light of the second wavelength formed in the region
A second mask comprising the interference filter described above is set on the mask and exposed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining a first embodiment of the present invention.

First, for example, a polysilicon film 3 which is a film to be etched is formed on the silicon substrate 1 on which the step 2 is formed, and then a resist film 4 is spin-coated thereon.
Next, exposure is performed using a mask, which is formed on a lower surface of quartz glass by light-shielding patterns 6A and 6A made of a light-shielding film.
B is used, and an interference filter is formed on the upper surface. In particular, this interference filter has a first region 10A corresponding to a thick resist film formed on the silicon substrate 1.
A first interference filter 8A that transmits only light of the first wavelength, and a second region 1 corresponding to a thin resist film.
0B is provided with a second interference filter 8B that transmits only light of the second wavelength. Exposure is performed by using the white light 9 using the mask configured as described above.

For example, when exposing the resist film 4 using a white light source that emits light having a wavelength of 300 nm to 800 nm inside the stepper, the first portion of the thick portion of the resist film of the light having a wavelength of 300 to 800 nm is used. 400 nm in the region 10A, and 500 n in the thin second region 10B.
Assuming that the standing wave effect does not occur with light having a wavelength of m, the first interference filter 8A on the quartz glass 4 emits light having a wavelength other than 400 nm, and the second interference filter 8B emits light having a wavelength of 500 nm.
The light of wavelengths other than the above is cut, and the resist film 4 is exposed. After the exposure, the unexposed portion is removed with a solvent by the same operation as in the prior art, and a pattern of a thick resist film 4A and a thin resist film 4B is formed on the silicon substrate 1.

The polysilicon film 3 is etched using the resist film as a mask.

As described above, according to the first embodiment, even when exposure is performed using a white light source, the thick resist film in the first region 10A has a wavelength of 400 nm through the optical lens 7.
, And the thin resist film in the second region 10B is exposed only by light having a wavelength of 500 nm.
Unlike the conventional case, there is no influence of the standing wave effect due to the difference in the thickness of the resist film. Therefore, the patterns of the thick resist film 4A and the thin resist film 4B as masks used for etching the polysilicon film 3 are formed with high precision.

FIG. 2 is a sectional view for explaining a second embodiment of the present invention, and uses a second mask in which an interference filter is formed on another quartz glass.

As a mask for exposing the resist film 4 formed on the silicon substrate 1, a first mask composed of light-shielding patterns 6A and 6B formed on quartz glass 5 and a mask set on the first mask are set. A second mask provided with an interference filter on quartz glass 5A is used. This second
Is a first interference filter 8 on quartz glass 5A.
A and a second interference filter 8B are provided, but the first and second interference filters 8A and 8B are formed of a thick resist film, like the first embodiment.
And the second region 10B of the thin resist film. In this case, the distance between the quartz glass forming the first and second masks and the distance from the light-shielding patterns 6A and 6B to the resist film 4 are determined in consideration of the effect of the standing wave effect, and the transmission wavelength of the interference filter is adjusted. decide.

As described above, according to the second embodiment,
Since the thick resist film and the thin resist film are respectively exposed to light of different single wavelengths, the patterns of the thick resist film 4A and the thin resist film 4B as masks are accurate as in the case of the first embodiment. Well formed.

The interference filter is formed by forming a laminated film such as a metal film and a dielectric film on a quartz glass so as to have characteristics as a first interference filter, and patterning the film by a dry etching method or the like. Then, a method of forming a first interference filter in the region and then similarly forming a laminated film on the entire surface and patterning to form a second interference filter in the second region is used.

[0023]

As described above, the present invention uses an interference filter having a different transmission wavelength to change the wavelength of light to be exposed according to the difference in the thickness of a photoresist film on a semiconductor substrate. By forming the mask in this manner, the effect of the standing wave effect, which has been a problem, is eliminated, so that a highly accurate pattern can be formed on the photoresist film.
For this reason, it is not necessary to correct the dimension of the light-shielding pattern for correcting a characteristic shift due to a decrease in patterning accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view for explaining a second embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 step 3 polysilicon film 4, 4A, 4B resist film 5, 5A quartz glass 6A, 6B light shielding pattern 7 optical system lens 8A first interference filter 8B second interference filter 9 white light 9A light 10A first Area 10B second area

Claims (2)

(57) [Claims] A photoresist film is formed on a semiconductor substrate on which a step is formed, and then a thick photoresist film and a thin photoresist film are formed using a mask having a pattern of a light shielding film formed on one surface of a quartz substrate. In a method of manufacturing a semiconductor device for forming a pattern by exposing and developing
A first interference filter that transmits only light of a first wavelength is formed in a first area corresponding to the thick photoresist film on the other surface of the quartz substrate, and a second interference filter corresponding to the thin photoresist film is formed. A method for manufacturing a semiconductor device, comprising using a mask having a second interference filter that transmits only light of a second wavelength in a region. 2. A method of manufacturing a semiconductor device, comprising: forming a photoresist film on a semiconductor substrate having a step formed thereon, and exposing and developing a thick photoresist film and a thin photoresist film using a mask to form a pattern. A first interference filter formed on a quartz substrate, a first region corresponding to the thick photoresist film on the quartz substrate and transmitting only light of a first wavelength, and a first interference filter corresponding to the thin photoresist film. Manufacturing a semiconductor device, wherein a second mask formed of a second interference filter formed in the second region and transmitting only light of a second wavelength is set on the mask and exposed. Method.