JPS60224226A - Pattern forming method for resist film - Google Patents

Abstract

PURPOSE:To facilitate the positioning of a photomask accurately and to improve the yield by exposing a positioning mark on a substrate partly from a thick resist film. CONSTITUTION:The second resist film 26 and the first resist film 23 are exposed and developed with the same first photomask 27 as the pattern of a thin film 24, and the first resist film 23 and the second resist film 26 on the positioning mark 22 of a substrate 21 are partly removed to expose the mark 22. Then, the second photomask 28 having the prescribed pattern is disposed on the second thin resist film 26 so that the positioning mark 29 of the photomask 28 and the positioning mark 22 of the substrate 21 coincide, exposed and developed, the second film 26 is first patterned in the prescribed pattern, with the film 26 pattern as a mask the film 24 made of aluminum directly under the mask is selectively etched to form a thin film mask 24a.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for forming a pattern on a resist film, and particularly in patterning a resist film, the positioning of a photomask can be performed with high precision, and the pattern accuracy is good. The present invention relates to a method for forming thick resist film patterns with high yield.

佽) Technology background When manufacturing thin-film magnetic heads and semiconductor integrated circuits, etc.
Thin film formation technology and photolithography technology have become essential technologies.

When patterning a resist film using these techniques, the thickness of the resist film and the precision of its pattern width are in a contradictory relationship. That is, a thin resist film with a film thickness of about 0.2 to 0.5 μm has good pattern accuracy, but
As the film thickness increases, pattern accuracy decreases due to light diffraction phenomenon during exposure. In recent electronic devices using thin films, the underlying pattern often has a high step, and thin resist films This results in defective step coverage.Furthermore, when a thin film device is formed using a technique such as plasma etching, ion etching, mask plating, etc. using a resist film pattern as a mask, a thick resist film is inevitably required.

However, when the thickness of the resist film becomes as thick as 2 to 5 μm, it becomes extremely difficult to ensure pattern accuracy.

(C1 Prior Art and Problems The conventional method of forming a resist film pattern that has been proposed to solve the above-mentioned problems is as follows: As shown in the cross-sectional view of FIG. 2 along the periphery, a thick resist film 3 and aluminum (
Aj)Ill! 4 and a thin resist film 5 are deposited in this order. Next, as shown in FIG. 3, a thin resist film 5 is patterned into a predetermined pattern, and using this resist 111!5 pattern as a mask, the M film 4 is selectively etched, and the alignment marks 2 on the substrate 1 are etched. AZy corresponding to the part! Remove 4 parts. Next, as shown in FIG. 4, a photomask 6 having a predetermined pattern is placed on the thin resist film 5 so that the alignment mark 7 of the photomask 6 and the alignment mark 2 of the substrate 1 match. ,
First, the thin resist 115 is patterned into a predetermined pattern by exposure and development, and using this resist film pattern as a mask, the Al odor 4 is selectively etched to form a metal mask 4a as shown in FIG. do. After that, the thick resist 11! is applied through the metal mask 4a!
3 is exposed and developed to form a predetermined pattern as shown in FIG.
By selectively etching away the thin resist Im! 5 is also removed, forming a thick resist film pattern 3a with a desired fine width as shown in FIG.

However, in the conventional resist film pattern forming method described above, the photomask 6 having a predetermined pattern on the thin resist film 5 is aligned with the alignment mark 7 of the photomask 6, for example, as explained in the step of FIG. When aligning the alignment marks 2 on the substrate l so that they match, alignment is performed through a thick resist film 3, but the resist film 3 is as thick as 3 to 5 μm. Therefore, the alignment mark 2 on the substrate 1 becomes unclear, making it difficult to accurately align the photomask 6, resulting in a decrease in the yield of resist film pattern formation.

(d) Purpose of the Invention In order to eliminate the above-mentioned conventional drawbacks, the present invention provides a method for aligning the alignment marks on the substrate when aligning the alignment marks on the photomask to match the alignment marks on the substrate. By exposing parts of the thick resist film, alignment of the photomask is easy and accurate (
The object of the present invention is to provide a novel resist film pattern forming method that improves the formation yield.

According to the present invention, a first resist film, an optically opaque thin film in a region excluding the alignment mark, and a step of sequentially forming a second resist film thinner than the first resist film, and removing a second resist film other than the area to which the optically opaque thin film is deposited to form a substrate. a step of exposing the upper alignment mark, and a step of placing a photomask on the second resist (Ill) with reference to the alignment mark on the substrate, and patterning the second resist film into a predetermined pattern. a step of selectively etching the opaque thin film using the patterned second resist film as a mask; and a step of selectively exposing and developing the first resist film using the thin film pattern as a mask; This is achieved by providing a method for forming a resist sunflower pattern, which is characterized by patterning the resist sunflower into a pattern.

(f) Embodiments of the invention Embodiments of the invention will be described in detail below with reference to the drawings.

FIGS. 8 to 14 are schematic cross-sectional views showing one embodiment of the resist film pattern forming method according to the present invention in the order of steps.

First, as shown in Figure 8, positioning marks 2 are placed on the periphery.
A first resist film 23 made of a positive photoresist is applied to a thickness of 3.5 μm on the substrate 21 marked with 2.
Using a vapor deposition mask 25 on top of it, a vapor deposition method or the like is performed to obtain a 0.
An opaque thin film 24 of aluminum (Aj) with a thickness of 1 μm is formed as shown.

Next, as shown in FIG. 9, a second resist film 26 with a thickness of 0.5 μm is coated on the first resist film 23 including the thin film 24, and then the second resist film 26 and the second resist film 26 are coated. 1 resist II! 23 is exposed and developed using a first photomask 27 having the same shape as the pattern of the thin film 24.
As shown in the figure, the first resist II! on the alignment mark 22 of the substrate 21! ! 23 and second register) Il
! J! 26 is partially removed to remove the alignment mark 22.
expose.

Next, as shown in FIG. 11, a second photomask 2 having a predetermined pattern is formed on the second thin resist film 26.
8 is arranged so that the alignment mark 29 of the photomask 28 and the alignment mark 22 of the substrate 21 match, and exposure and development are performed to first pattern the second resist film 26 into a predetermined pattern. Using the pattern of the resist film 26 as a mask, the thin FJ 24 made of aluminum immediately below it is selectively etched to form a thin film mask 24a as shown in FIG. This etching can be easily and accurately performed by wet etching using a phosphoric acid etching solution without causing undercuts.

Thereafter, the first resist film 23 is exposed and developed through the thin film mask 24a to form a predetermined pattern as shown in FIG. 13, and the thin film mask 24a on the pattern is selectively etched away. As a result, the thin second resist film 26 thereon is also removed, making it possible to accurately form a thick resist film pattern 23a with a desired fine width, as shown in FIG.

According to this example, the resist film pattern with a line width of 1.5 μm and a resist film thickness of 3.5 μm had no edge sag and had good pattern accuracy.

Furthermore, the mask material for forming the thin film mask is not limited to the aluminum thin film of this example, but also titanium (Ti).
Needless to say, it can be carried out using a thin film such as permalloy (Ni-re) which is opaque, non-transparent and can be easily removed by etching.

(a) Effects of the Invention As is clear from the above explanation, according to the resist film pattern forming method of the present invention, photomask alignment can be performed with high precision and easily without increasing the number of steps. This method has the excellent effect of forming thick resist film patterns with high accuracy and high yield.Therefore, it is extremely advantageous when applied to the formation of fine width patterns of thick resist films.

[Brief explanation of the drawing]

1 to 7 are diagrams for explaining the conventional resist film pattern forming method step by step. FIG. 1 is a perspective view, and FIG. FIGS. 3 to 7 are cross-sectional views, and FIGS. 8 to 14 are cross-sectional views showing the method of forming a resist film pattern according to the present invention in the order of steps. In the drawing, 21 is a substrate, 22 is an alignment mark on the substrate 21, 23 is a first resist film, 23a is a thick resist film pattern, 24 is an opaque thin film, 24a is ll
25 is a film mask, 25 is a vapor deposition mask, 26 is a second resist film, 27 is a first photomask, 28 is a second photomask, and 29 is an alignment mark of the second photomask 28. Figure 1 Figure 2 Figure 4 Flash 5th Cause Figure 7 Figure 8 Figure 10r Figure 12, 6 Figure 13r Figure 14rM Procedural amendment stamp button April 23, 1985 Ichisho Commissioner's Palace Incident Display Patent Application No. 80720 filed in 1980 Name of the invention Relationship with the person who amends the pattern formation method of a resist film Patent applicant Address 1015-5 Kamiodanaka, Nakahara-ku, Yozaki City, Kanagawa Prefecture
22) Name Fujitsu Ltd. Agent Postal code 211 6.1 Contents of pressure Part 5 (1) “On top of that...” on page 4, line 13 of the specification of the application
...removed," is deleted. (2) On page 8, lines 15-16, the phrase ``The thin second layer above it...is removed'' is deleted. (3) The attached drawings Figures 6 and 13 are amended as shown in the attached sheet. 9. Attached document inventory correction drawings: 1 copy or more Figure 6 Figure 13

Claims (1)

[Claims] A first resist film, an optically opaque thin film in an area excluding the alignment mark, and a second resist film thinner than the first resist film are formed on a substrate with alignment marks attached to the peripheral part.
a second resist film in a region other than the area to which the optically opaque thin film is deposited; removing the first resist film to expose the alignment marks on the substrate; arranging a photomask on the second resist film with reference to the alignment marks on the substrate; A step of buttering the film into a predetermined pattern, a step of selectively etching the opaque thin film using the patterned second resist film as a mask, and a step of selecting the first resist film using the thin film pattern as a mask. A method for forming a pattern on a resist film, the method comprising patterning a resist film into a predetermined pattern by exposing and developing the resist film.