JPS59103337A - Pattern formation - Google Patents

Abstract

PURPOSE:To obtain a metal film of micro-miniature pattern by covering the entire part with a positive resist film, when etching a metal film deposited on a semiconductor substrate through an insulating film, opening an window and filling it with a polyimide film which is resistive to dry etching, removing the resist film leaving only such polyimide film and by etching the metal film with the polyimide film used as the mask. CONSTITUTION:An Al film 10 is deposited on a semiconductor substrate 1 through an insulating film 2, a positive resist film 11 is provided on the entire part, it is then exposed by the electronic exposing method and developed, and a window is opened in the desired region. A polyimide film 12 which is resistive to dry etching is applied to the entire part including the window and is baked. While adjusting such baking time, ion etching is carried out. Thereby, the film 12 is left only within the window. Thereafter, with the film 12 used as the mask, the film 11 in the periphery is removed by the O2 plasma. With the film 12 left used as the mask, the reactive ion etching is carried out to the film 10 using CCl4 and thereby the desired shape of Al film 10 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION +a) Technical Field of the Invention The present invention relates to a pattern forming method, and particularly to a method of forming a fine pattern with high precision.

(bl) Prior art and problems When manufacturing semiconductor devices such as semiconductor integrated circuits (ICs), miniaturization of patterns is required to improve the performance of semiconductor devices, and the dry etching method has replaced the conventional wet etching method. Etching methods have come to be used frequently because dry etching methods add a sputtering effect and are less likely to cause side etching, which improves pattern accuracy.

However, when dry etching is performed, the mask of the resist film is easily damaged, which has the disadvantage that pattern accuracy deteriorates. For example, as shown in FIG. 1, an aluminum film 3 is deposited on a semiconductor substrate 1 via an insulating film 2,
When a resist film 4 mask is formed on the upper surface and etched, a pattern of the aluminum film 3 with poor precision as shown in FIG. 2 is formed. Such a resist film is
For example, the higher the sensitivity and resolution of a resist film such as PMMAIQ used in electron beam exposure, the weaker the resistance to dry etching. Must not be. Therefore, forming extremely fine patterns with a width of about 0.5 to 1 μm, for example, has become a very difficult problem.

(C) Object of the Invention The present invention solves the above-mentioned problems and proposes a pattern forming method for forming fine patterns with high precision.

(11 Structure of the Invention The purpose is to form a resist film pattern on a material to be etched, and to form a dry etching-resistant organic material film on the upper surface of the resist film pattern, and then to etch the organic material film to remove the resist film. Achieving this by a pattern forming method that includes the steps of leaving the organic material film in the window of the pattern, then removing the resist film pattern, and etching the material to be etched using the remaining organic material film as a mask. Can be done.

(el　Embodiments of the invention An embodiment will be described in detail below with reference to one drawing.

3 to 9 are cross-sectional views in the order of steps of an embodiment according to the present invention. First, as shown in FIG. niP
The entire MMA film 11 is exposed by electron beam exposure. Then, a mask pattern of PMMAIIffll as shown in FIG. 4 is formed. This PMMA film 11 total 11
A resist film with a thickness of about 0.5 to 1 μm.

Next, as shown in FIG. 5, a polyimide film 12 having a thickness of 2 .mu.m is applied thereon and baked at about 200.degree. By applying it thickly in this manner, the surface of the polyimide film can be flattened. Next, as shown in FIG. 6, the entire surface of the polyimide film is etched by an ion milling method (a type of dry etching method) using argon gas, and the etching time is adjusted so that the polyimide film 12 remains only within the window of PMMAIIQ. . Next, as shown in FIG. 7, the entire PMMA film 11 is removed by plasma etching using oxygen gas. in this case,
Since polyimide film is difficult to be etched by oxygen gas plasma, PMM can be removed by adjusting the etching and notching time.
The polyimide film 12 can be left by removing the A film. Alternatively, instead of using the oxygen gas plasma etching step (not shown in FIG. 7), the entire PMMA film 11 can be removed at the same time by the ion milling method using argon gas as described above, leaving the polyimide film 12 inside the window. . This is because PMMA films are much more easily etched than polyimide films by ion milling using argon (Ar).

Next, as shown in FIG. 8, the aluminum film 1o is coated with carbon tetrachloride (CC) using the polyimide film 12 as a mask pattern.
14) Etching using gas or active ion etching. Next, when the mask pattern of the polyimide film 12 is removed by oxygen gas plasma etching, a fine pattern of the aluminum film 10 is formed with high precision as shown in FIG.

In this way, fine patterns with a width of 0.5 to 1 μm can be easily formed, and the present invention can be applied to insulating films such as silicon and silicon oxide in addition to the above-mentioned aluminum film to produce submicron patterns with similar accuracy. A pattern can be formed.

(f) Effects of the Invention As is clear from the above description, according to the present invention, submicron patterns can be formed with a precision of 2, which is extremely useful for improving the performance and reliability of semiconductor devices.

[Brief explanation of the drawing]

1 and 2 are step-by-step cross-sectional views of a conventional pattern forming method, and FIGS. 3 to 9 are step-by-step cross-sectional views according to the present invention. In the figure, 1 is a semiconductor substrate, 2 is an insulating film, 3 is an aluminum film, 4 is a resist film, 10 is an aluminum film, and 11 is a P
MMA film (positive resist film). Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 9 Fig. 9 Showa Tough F Usuma') 11th F1,! / 3 / 3!
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People (L place, Kamireiyo Prefecture, Yosaki City, 1st grade, 1st grade, 1st grade, 101st grade)
Address 5 (522) Name (j, Fujitsu Ltd. 4 Agent fL+'li Kanagawa Prefecture Yosakiyama Nakaha; 1 Ward I11/Ill Naka 1015 City 5,
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Tsukino 2j1 (Shipping 1)

Claims (1)

[Claims] A step of forming a resist film pattern on a material to be etched and forming a dry etching-resistant organic material film on the upper surface of the resist film pattern, and then etching the organic material film to form the organic material film within the window of the resist film pattern. A pattern forming method comprising a step of leaving the resist IIQ pattern, and then etching the material to be etched using the remaining organic material film as a mask.