JPS6281714A - Pattern formation - Google Patents

Abstract

PURPOSE:To reduce a transfer error in pattern measurement in case of dry etching of a base semiconductor substrate or a film made of a different substance from of the substrate by using a resist pattern as a mask by using a negative far ultraviolet ray resist as a lower layer resist in PCM technique. CONSTITUTION:On an Si substrate 1, a polysilicon layer 2 is formed and on the polysilicon layer 2, a negative far ultraviolet ray resist material 3 is spread. After that, the substrate is subjected to a heat treatment using a convection type oven and a positive photoresist material 4 consisting of novolak resin is spread and a heat treatment on a heat plate is performed. Next, the photoresist material except openings is exposed followed by development and the resist material of the exposed part is removed. Furthermore, the overall surface of the substrate is irradiated with sufficiently parallel far ultraviolet rays. Next, the development is performed by using a mixed solvent of methyl ethyl and inpropyl alcohol and a pattern 4a composed of a photoresist material and a negative far ultraviolet ray resist material right under said pattern 4a are removed. Subsequently, a base polysilicon layer 2 is etched by using a pattern 3a as a mask.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pattern forming method, and more particularly to a pattern forming method on various semiconductor substrates in the production of semiconductor integrated circuits, and more particularly on a pattern forming method on various semiconductor substrates having steps. The present invention relates to a method for forming a fine pattern.

[Conventional technology]

Conventionally, P is a method for forming fine patterns on a semiconductor substrate having steps using a coating agent such as a resist.
CM (Portable Comformable
A method called "Mask" was proposed. This method will be explained based on FIGS. 2(a) to 2(d). First, Figure 2 (
As shown in a), a positive deep ultraviolet resist material 5 such as PMMA (polymethyl methacrylate) having a photosensitive range mainly from 200 to 250 nm is applied to the surface of the semiconductor substrate on which polycrystalline silicon 2 is formed, and then 350～
A UV resist material 4 such as a facultative novolac resin having a 450 nmK photosensitive range is applied. Next, Figure 2 (b
), an ultraviolet resist pattern 4a is formed only on the upper ultraviolet resist film by exposing it to ultraviolet light using an exposure device having a light source of ultraviolet light of 300 to 450 nm, and then developing it. At this time, since the lower deep ultraviolet resist film has a different photosensitive range and is not exposed to light, openings can be formed in the upper ultraviolet resist film by development.

Next, as shown in FIG. 2(C), the entire surface of the semiconductor substrate is irradiated with sufficiently parallel deep ultraviolet rays having a wavelength of about 200 to 250 nm. In the remaining part of the upper ultraviolet resist film 4a, this part absorbs deep-violet IA rays and serves as a mask for the lower resist film directly below it, so it is irradiated with far-ultraviolet rays using an appropriate solvent to remove low-molecular-weight molecules. By developing and removing the lower resist film, a positive deep ultraviolet pattern 5a is obtained. When developing the lower resist film,
The upper resist film may or may not be dissolved. Next, by dry etching the polycrystalline silicon using the formed resist pattern 5a or 5a and 4a as a mask as shown in FIG. 2(d), the fine pattern can be transferred to the polycrystalline silicon.

[Problem that the invention seeks to solve]

The conventional PCM method described above uses a positive deep ultraviolet resist as the lower layer.

In general, positive type deep ultraviolet resists have poor resistance to parallel plate type reactive dry etching, that is, dry etching resistance. This is because when a positive far-UV resist material is irradiated with far-UV rays or heat, the polymer collapses, but when etching is performed by dry etching, the resist material is irradiated with energy equivalent to far-UV rays or electron beam irradiation. This is because the polymer collapses during dry etching.

For this reason, there is a drawback that when a fine pattern formed by a resist material is transferred by dry etching to an underlying semiconductor substrate or to another material film different from the substrate, a transfer error in pattern dimensions becomes large.

The present invention eliminates the above-mentioned conventional drawbacks, makes the resist pattern dry-etching resistant, and uses the formed resist pattern as a mask to dry-etch the underlying semiconductor substrate or a film of a material different from the substrate. An object of the present invention is to provide a pattern forming method that can reduce transfer errors.

Means for Solving Problem C] The pattern forming method of the present invention includes forming a first film made of a negative deep ultraviolet resist material directly on a semiconductor substrate having steps or through a film of a material different from the substrate. forming a second film made of an ultraviolet resist material on the film; and exposing and developing the second film to form a pattern made of the ultraviolet resist material in an opening formation area. and irradiating the entire surface of the substrate on which the second coating pattern is applied with deep ultraviolet rays, and then developing it to remove the second coating pattern and the negative deep ultraviolet resist material immediately below it. a step of forming a pattern made of a negative deep ultraviolet resist material, and a step of etching a base semiconductor substrate or another material film different from the substrate using the pattern as a mask to obtain a fine pattern. There is.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1A to 1D are cross-sectional views shown in order of steps to explain an embodiment of the present invention.

first,! l! As shown in Figure 1 (ta), a polycrystalline silicon layer 2 with a thickness of about 06 μm is formed on a silicon substrate 1 with a step of about 05 μm, and a negative deep ultraviolet resist material 3 is formed on the polycrystalline silicon layer 2. For example, Toyo Soda's CMS
- Apply DU to a thickness of 1.5 μm. After that, heat treatment was carried out for 110"0125 minutes using a convection method, and then a positive photoresist material 4, which is better than ordinary novolac resin, such as 0FPR800 manufactured by Tokyo Ohka Co., Ltd., was applied to a thickness of 1.Qμm.
The film was applied to a thickness of 100° C. and heated on a hot plate at 100° C. for 60 seconds.

Next, as shown in FIG. 1(b) K, the photoresist material other than the openings is exposed to light, and then the photoresist material is exposed to light for 50 seconds using a developer, for example, a positive photoresist developer NMD-3 manufactured by Tokyo Ohka. Develop and remove the exposed portions of the resist material. Furthermore, although the entire surface of the substrate is irradiated with sufficiently parallel far ultraviolet rays, the negative type far ultraviolet resist layer immediately below the pattern 4a made of a photoresist material is not exposed because the pattern 4a absorbs the far ultraviolet rays and serves as a mask for the underlying layer.

Next, as shown in Fig. 1fc), development was carried out for 80 seconds using a solvent containing a mixture of methyl ethyl Kent and Inglobil alcohol at a ratio of 3:1, and pattern 4a made of photoresist material and the unfinished area immediately below it were developed. Removes photosensitive negative deep ultraviolet resist material. In this case, a pattern 3a made of a negative type deep ultraviolet resist material as shown in the figure can be obtained with good line width controllability at the step portion.

Next, as shown in FIG. 1(d), the underlying polycrystalline silicon layer 2 is etched using a dry etching device using the pattern 3a as a mask. At this time, the transfer error in the notch dimension can be made smaller than when a positive deep ultraviolet resist material such as PMMA is used.

〔Effect of the invention〕

As explained above, in the present invention, by using a negative type deep ultraviolet resist as the lower layer resist in the PCM method, it is possible to make the resist pattern more resistant to dry etching than when using a conventional positive type deep ultraviolet resist. This method has the effect of reducing transfer errors in pattern dimensions when dry etching a base semiconductor substrate or a film of a material different from the substrate using the resist pattern as a mask.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are cross-sectional views taken in order of process to explain an embodiment of the present invention, and FIGS. 2(a) to fd) are cross-sectional views showing a pattern forming method using the conventional P (J4 method). 1 is a cross-sectional view shown in order of steps for explanation. 1... Semiconductor substrate, 2... Polycrystalline silicon, 2a... Polycrystalline silicon pattern, 3.
・・・・・・Negative deep ultraviolet resist, 3a・・・・・・
Negative deep ultraviolet resist pattern, 4...UV resist, 4a...UV resist pattern, 5...Positive deep ultraviolet resist, 5a...
...Positive deep ultraviolet resist pattern. 2' Agent Patent Attorney 5v〉 ) n 4 $ 2

Claims (1)

[Claims] A step of forming a first coating made of a negative-type deep ultraviolet resist material on a semiconductor substrate having a step directly or through a film of a material different from the substrate, and a second coating made of an ultraviolet resist material on the coating. a step of exposing and developing the second film to form a pattern made of an ultraviolet resist material on the aperture forming area; irradiating the entire surface of the substrate with far ultraviolet rays and then developing it to remove the second coating pattern and the negative far ultraviolet resist material immediately below it to form a pattern made of the negative far ultraviolet resist material, and the pattern A pattern forming method comprising the step of etching a base semiconductor substrate or another material film different from the substrate using the mask as a mask to obtain a fine pattern.