JPS62115722A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To form a fine pattern of a rectangular shape with no roundness at a corner section by conducting first anisotropic etching by a first resist pattern for shaping oppositely faced two sides and performing second anisotropic etching by a second resist pattern for forming two sides crossing with two sides when forming a mask pattern. CONSTITUTION:A silicon oxide film 2 of 6,000Angstrom is shaped onto a P-type silicon substrate 1 through thermal oxidation, first resist patterns 3 are formed to a striped shape, and the oxide film 2 is etched by reactive ions, using the patterns as masks. The first patterns 3 are removed, and second resist patterns 4 are formed to a striped shape in the direction that they cross with the pattern of the oxide film 2. The oxide film 2 is reactive-etched again, employing the second patterns 4 as masks, and the second patterns 4 are removed, thus acquiring a rectangular silicon oxide-film pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a fine pattern by etching a region not covered with a mask material in the formation of a semiconductor element.

[Prior art and its problems]

In recent years, with the increasing integration of semiconductor devices, remarkable progress has been made in the formation of fine patterns due to improvements in lithography technology and dry etching technology. For example, Journal of Vacuum Science and Technology (J, Vac, Sci, Technol
, ) Vol. 15, 1978, pages 319-326, it was reported that it was possible to form a silicon oxide film pattern with a vertical cross-sectional shape without changing the mask pattern width by reactive sputter etching using carbon tetrafluoride gas. has been done. In addition to this example, in reactive sputter etching, by appropriately selecting the etching gas and etching conditions, it is possible to process not only silicon oxide films but also insulators, semiconductors, metals, etc. in accordance with the mask dimensions. On the other hand, lithography technology uses ultraviolet light reduction projection exposure instead of the traditional light projection exposure method.

The development of X-ray exposure and electron beam exposure technologies has made it possible to control line widths with submicron resolution.

However, even when the above-described exposure technique is used, there is a problem in forming fine rectangular patterns because the edges of the pattern are rounded.

For example, when a reticle pattern 21 as shown in FIG. 2(a) is transferred onto a substrate using the ultraviolet light reduction projection exposure method, as shown in FIG. 2(b), some corners of the resist pattern 22 are Rounding occurs at the corners of the resist pattern. This phenomenon is not limited to light exposure, but also to X-ray exposure.

This is an unavoidable problem in electron beam exposure as well, although there are differences in degree, and is caused by the diffraction phenomenon of the irradiation beam. If the resist pattern has a shape as shown in FIG. 2(b), if anisotropic etching is used, it will be etched in accordance with the resist pattern, which will be a hindrance to the formation of fine semiconductor elements.

[Purpose of the invention]

An object of the present invention is to provide a method for forming a fine pattern having a rectangular shape by eliminating roundness in a part of the corner of the pattern during fine pattern processing in the formation of a semiconductor element.

[Structure of the invention]

The present invention involves forming a mask pattern on a substrate or a film deposited on the substrate using an exposure technique, and anisotropically etching the substrate or the film deposited on the substrate that is not covered by the mask pattern. In the pattern forming method, a mask material is anisotropically etched using a first resist pattern for forming two opposing sides of a rectangular mask pattern, and then a second resist pattern for forming two sides intersecting the two sides. anisotropically etching the mask material to form a resist pattern, and using the obtained rectangular mask pattern, anisotropically etching an uncoated substrate or a film deposited on the substrate to form a rectangular pattern; It is characterized by

[Detailed explanation of the configuration]

The present invention has solved the problems of the prior art by adopting the above configuration. According to the present invention, when forming a mask pattern used for anisotropically etching a substrate or a film deposited on a substrate, a first resist pattern for forming two opposing sides is used to form a first resist pattern. Anisotropic etching is performed, and then second anisotropic etching is performed using a second resist pattern for forming two sides intersecting the two sides. By this procedure, it is possible to suppress the so-called corner drop phenomenon in which a portion of the mask pattern corner is rounded. Using the mask pattern obtained in this way, the actual substrate or the film deposited on the substrate is anisotropically etched by reactive ion etching to form a rectangular pattern with no rounding at some of the pattern corners. It becomes possible. Therefore, even when the pattern becomes finer, it is possible to form a part of the pattern corner keeping its rectangular shape.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing a cross section or a front structure in the main manufacturing process for explaining one embodiment of forming a fine groove type element isolation region using the method of the present invention.

In this example, first, a 6,000-layer silicon oxide film 2 is formed on a p-type silicon substrate 1 with a (100) plane orientation by thermal oxidation, and then a first resist pattern 3 is formed in a stripe shape. Silicon oxide 11'J using the pattern as a mask! When 2 is subjected to reactive ion etching, the structures shown in FIGS. 1(a) and 1(a') are obtained. Next, after removing the first resist pattern 3, a second resist pattern 4 is formed in a stripe shape in a direction intersecting the pattern of the silicon oxide film 2, as shown in FIG.
') get the structure. Next, the silicon oxide film 2 is reactively etched again using the second resist pattern 4 as a mask.
When the second resist pattern 4 is removed, FIG. 1(c)
, A rectangular silicon oxide film pattern as shown in (c') is obtained. As described above, in the rectangular silicon oxide film pattern as a mask pattern obtained by the above procedure, the corner drop phenomenon is suppressed, and therefore some of the pattern corners maintain a rectangular shape. Next, using this silicon oxide film pattern as a mask, the silicon substrate 1 is subjected to reactive ion etching to form a silicon groove 5 with a depth of 3 μm, and the silicon oxide film 2 is removed, as shown in FIG. 1(d).
Obtain the structure of (d'). A thermal oxide film 6 of about 1,000 layers is formed on the surface of the silicon substrate 1 having the grooves obtained by the above procedure, and then a silicon nitride film 7 of about 500 layers is deposited by low pressure CVD method. When the polycrystalline silicon film 8 is deposited by the CVD method until the trench is filled, the first
The structure shown in figure (e) is obtained. Next, the polycrystalline silicon film 8 is etched back so that it remains only in the region of the groove 5, and the surface of the polycrystalline silicon embedded in the groove is oxidized to 5i02.
CVD silicon nitride film 7 on the surface of the silicon substrate as layer 9
Then, the silicon oxide film 6 is removed to obtain a substrate having the structure shown in FIG. 1(f). Through such a procedure, an element isolation region with almost no change in mask dimensions was formed.

As described above, according to this embodiment, it is possible to form a micro-groove element isolation region while maintaining the rectangular shape, so that a reduction in the area of the device active region can be avoided.

In the above embodiments, a mask pattern is formed on a silicon substrate, but if a film such as an insulator or a conductor is deposited on the substrate, the method of the present invention can be applied to anisotropic etching of the film. Of course it can be used.

〔Effect of the invention〕

As described above, according to the present invention, when forming a mask pattern, two opposing sides are formed. 1st for
The first anisotropic etching is performed using a resist pattern, and then the second anisotropic etching is performed using a second resist pattern for forming two sides that intersect with the two sides. A mask pattern with no roundness in a portion was obtained, making it possible to form a fine pattern with a rectangular shape.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional or front structural schematic diagram showing step by step the manufacturing method for forming a groove-type element isolation region in an embodiment of the present invention. FIG. 2 is a transfer of a reticle pattern and a resist pattern using a conventional method. It is a schematic diagram showing a change. ■...Silicon substrate 2.6...Silicon oxide film 3...First resist pattern 4...Second resist pattern 5...Silicon groove 7... ...CVD silicon nitride film 8...CVD polycrystalline silicon film 9...5j0 obtained by oxidizing polycrystalline silicon
21W 21...Reticle pattern 22...Resist pattern

Claims (1)

[Claims] (1) A mask pattern is formed on the substrate or a film deposited on the substrate using exposure technology, and the substrate or the film deposited on the substrate not covered by the mask pattern is anisotropically etched into a fine pattern. In the forming method, a mask material is anisotropically etched using a first resist pattern for forming two opposing sides of a rectangular mask pattern, and then a second resist pattern is etched for forming two sides intersecting the two sides. The mask material is anisotropically etched using a resist pattern, and an uncoated substrate or a film deposited on the substrate is anisotropically etched using the obtained rectangular mask pattern to form a rectangular pattern. A method for forming fine patterns.