JPS60132328A - Photoresist pattern forming method - Google Patents

Abstract

PURPOSE:To form a microscopic pattern in excellent reproducibility by a method wherein a side wall of narrow width is formed leaving a thin film only formed on the side face of a pattern, and after a photoresist has been roller coated on the whole surface, the side wall material is exposed by removing the film only on the surface of the side wall. CONSTITUTION:A pattern 12 is formed on a substrate 11 using Al and the like, and after SiO213, for example, has been coated on the whole surface by performing a CVD method, the film 13 located on the surface of the Al pattern 12 and the substrate 11 is removed. Then, when the Al pattern is removed using phosphoric acid and the like, a side wall 14 only is left. At this point, when a photoresist 15 is rotary painted on the whole surface, the photoresist is thinly coated on the upper surface of a side wall 15, and the upper surface of the side wall 15 is exposed by performing an etching using an RIE method again. Then, the exposed side wall is removed using phosphoric acid, and a microscopic photoresist pattern corresponding to the thickness of the side wall can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a photoresist pattern, in particular a method for forming a photoresist pattern of 0.5 μm without using special means such as electron beam exposure.
The present invention relates to a photoresist pattern forming method that allows fine patterns of less than m in size to be easily formed.

In recent years, integrated circuit technology has made remarkable progress, and large-scale integrated circuits (LSIs) for storage, each consisting of several hundred kilobits, are now being prototyped in various places. It is widely agreed that the miniaturization of patterns has a very important meaning in this technological trend, as is the case with the so-called scaling law. On the other hand, recently, especially in compound semiconductor devices,
It has been found that pattern miniaturization causes new phenomena that could not be predicted from the conventional extension, such as ballistic trance, t'-burden i, and velocity oversheet phenomena. is starting to attract more attention. As described above, pattern miniaturization is one of the important pillars of semiconductor technology in general, and it can be said that the effects it brings are immeasurable.

From this point of view, various fine pattern forming methods have been researched and developed. One such method is, for example, a method of forming a fine photoresist pattern by exposure using an electron beam (EB exposure).

In this method, it is possible to form fine patterns of 0.5 μm or less, but there is a drawback that the finer the pattern, the longer the exposure time, resulting in a reduction in so-called throughput. Furthermore, the EB exposure apparatus itself is extremely expensive, and daily management, that is, maintenance, requires a large amount of cost. In addition to EB exposure, other technologies such as X-ray exposure technology and ion beam exposure technology are being researched and developed, but it can be said that these technologies are even more disadvantageous than the previously mentioned BB exposure technology.

The present invention was made in view of the above-mentioned shortcomings in the current photoresist fine pattern forming technology, and its purpose is to provide a 0.5
It is an object of the present invention to provide a photoresist pattern forming method capable of forming fine patterns of micrometers or less with good reproducibility.

The configuration of the present invention will be explained in detail using examples.

FIG. 1 is a diagram for explaining the photoresist fine pattern forming method according to the present invention. First, as shown in FIG. 1, a pattern 12 of a first material such as aluminum (Aυ, p) is formed on a substrate 11. In (b), a second material, such as 5i0213, is deposited on the entire surface to a thickness of 3000λ using a conventional chemical vapor deposition (CVD) method.Next, anisotropic dry etching is performed from a direction perpendicular to the substrate 11. For example, parallel electrode type reactive ion etching (
The 8i02 film 13 on the upper surface of the AI pattern 12 and on the surface of the substrate 11 is removed by (IE). At this time, the side surface of the AI pattern is coated with S.
ioz is formed as the side wall 14 ((C) of the same figure). Next, when the AI pattern is etched away using, for example, phosphoric acid, only the SiO□ sidewall 14 remains on the substrate 11, as shown in FIG.

Next, as shown in (e), a photoresist 15 is spin-coated over the entire surface. At this time, the photoresist on the upper surface of the side wall 15 is thinner than that on the substrate 11. Next, the photoresist is etched again by the RIE method, and the upper surface of the side wall 15 is exposed as shown in FIG. 3(f).

A fine photoresist pattern can be obtained. The pattern dimension d corresponds to the thickness of the 5i02 film deposited on the side surface of the AI pattern in the step (b).
Although it depends on the equipment, the 5i0 deposited on the
2 (in this example, 3ooo, i= ). In order to obtain a pattern with desired dimensions with high precision, it is sufficient to measure the relationship t-, tb between the thickness of Sioz deposited on the substrate and the thickness of the side wall.

Now, as described above, it can be seen that in the present invention, an extremely fine pattern corresponding to the thickness of the film of the second material (5i02) can be formed. Furthermore, another important feature of the method of the present invention is that the thickness of the photoresist film at that time is also thick enough to correspond to the height of the side wall, that is, to a thickness corresponding to the thickness of the first first material (A1). It is possible to obtain a pattern with a so-called large aspect ratio. In one embodiment, the pattern length is 0.
1μm ('1000＾゛), pattern thickness 07μm
It was possible to obtain a pattern with an aspect ratio of 7 (,7000λ") with good reproducibility.

Next, as another example of the present invention, as an application example of the photoresist fine pattern forming method according to the present invention, a 0.2 μm
A method for manufacturing a GaAs Schottky barrier gate field effect transistor (GaAs MESFET) with a long gate is shown. FIG. 2 shows the process diagram, and in (a), the thickness of 2000
A1 pattern 1 with a thickness of 0.7 μm is placed on a desired region on the active crystal layer 22 with a chiaria density of 1.5×10 cm
form 2. Thereafter, a fine pattern as shown in FIG. 2(b) is formed using exactly the same process as in the first embodiment. However, in this example, the thickness of the deposit 5i02 is 2.
000λ, the pattern dimension d is 200
0λ' (0.2 μm).

Further, the photoresist thickness is approximately 0.7 μm. Next, A123, which will become the gate electrode, is evaporated to a thickness of 04 μm over the entire surface.
)) By performing lift-off, a gate electrode 24 having a length of 0.2 μm and a thickness of 0.4 μm is formed as shown in FIG. Next, as shown in (e), the Au
If ohmic electrodes 25 and 26 made of Ge7Ni are formed, the gate length will be 0.211 m (D GaAs M, E
SFET is completed.

The method for forming a photoresist fine pattern according to the present invention has been described above, but the present method is also fully applicable to forming a fine pattern of a material having fluidity such as a polyimide resin film (PIQ).

In the embodiment, Al5 is used as the first and second substances, respectively.
Although SiCh was used, it goes without saying that a combination of 5102 and Si 3N4 or a combination of Sioz and A1 can be used to select the species.

[Brief explanation of the drawing]

Figures 1 (a) to (9) and Figures 2 (a) to (e) are diagrams for explaining each embodiment of the present invention.
... Board 12 ... AI pattern 13 ...
...5i02 film 14...Side wall 15...
・Photoresist 21...GaAs substrate 22・
・・・Active crystal layer 23 ・・・A1 gate metal 24 ・・・gate electrode 25, 26 ・・・
Ohmic Electrode Procedure Amendment (Method)' Director General of the Patent Office 1, Case Description 1981 Patent Application No. 240341
No. 2, Title of the invention Photoresist pattern forming method 3,
Relationship with the case of the person making the amendment Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent 5 Date of amendment order: March 27, 1980 (Delivery date) 6. Brief description of the drawings with specifications subject to amendment (7, Contents of amendment (1) Specification 1, page 7, line 14 ζ
~(f) Correct the text "J" to "Figure 1 (a) ~ tentative)".

Claims (1)

[Claims] (1) forming a pattern made of a first material in a desired area on a substrate; - forming a thin film made of a second material so as to cover the top and side surfaces of the pattern made of the first material and the surface of the substrate; removing the thin film of the second material deposited on the upper surface of the pattern of the 1Xx material and the surface of the substrate by anisotropic dry etching from a direction perpendicular to the substrate; A step of forming a sidewall by leaving a thin film made of the second material only on the side surface of the first material, a step of removing the first material, a step of spin-coating a photoresist film over the entire surface, and a step of dry etching. A method for forming a photoresist pattern, comprising the steps of: removing the photoresist film on the upper surface of the side wall made of the second material; and removing the exposed second material.