JPH02281628A - Contact hole and formation of thereof - Google Patents

Abstract

PURPOSE:To improve the coverage of a wiring metal film which is formed in an after process by a method wherein a hole which connects wirings with each other or a wiring with a board is formed into such a shape that it has two or more constricted parts. CONSTITUTION:An insulating film and a resist pattern are formed on a board 2, which is dipped into a wet etching solution to form a hemispheric hole. Then, the board 2 is subjected to a dry etching to form a hole of a first stage wet and dry etching. Hereafter, the same process is repeated once or more to make the hole become gradually larger toward its upper part in diameter, so that hole has a gentle slope which extends from its top to bottom. Thereafter, the resist is removed to form a cone-shaped contact hole which has two or more constricted parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contact hole shape of a semiconductor device and a method of manufacturing the same.

[Conventional technology]

FIGS. 2(a) to 2(e) are cross-sectional views showing the conventional contact hole manufacturing process. FIG. 2(e) shows the shape of a conventional contact hole, and FIG. 2(f) is a sectional view of the contact hole after metal wiring.

In the figure, % (1) is the insulating film, 12) is the substrate, (3) is the resist, % (4) is the wet etchant,
(5) is a dry etching gas, and (6) is a metal wiring film.

Next, the manufacturing flow will be explained. A resist pattern (3) is entirely formed on the insulating film (1) (FIG. 2(a)) formed on the substrate (2) (FIG. 2(b)). Next W
The wafer is placed in etching solution and etched (FIG. 2(C)), and the substrate is etched by dry etching (FIG. 2(d)). When the resist is then removed, the shape of the contact hole becomes one step (FIG. 2(e)).

[Problem to be solved by the invention]

Since conventional contact holes are formed as described above, it is difficult for the metal wiring film formed in the next process to completely cover the bottom hole (see Figure 2 (f)), which reduces reliability. The problem was that a defective device was manufactured.

This invention was made to solve the above-mentioned problems, and it is possible to completely cover the entire hole with the metal wiring film formed immediately after forming the contact hole, and to obtain a highly reliable device. The purpose is

[Means to solve the problem]

The contact hole according to the present invention is formed by repeating isotropic etching and anisotropic etching several times after forming a resist pattern so that the metal wiring film formed in the next step can sufficiently cover the hole. , the contact hole is sloped to near the bottom and has a concave shape with a constriction of more than -step.

[Effect]

The contact hole formed as described above has a gentle slope up to the vicinity of the bottom, and has good coverage with the wiring metal film formed in the next step.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

1(a) to 1(g) are cross-sectional views showing the manufacturing process of a contact hole in one embodiment, and FIG. 1(g) shows its shape. Further, FIG. 1(h) shows a cross-sectional view after metal wiring is formed in the contact hole shown in FIG. 1(g).

Items (1) to (6) are completely the same as the conventional device described above.

Next, the manufacturing flow will be explained. A BPSG film having a thickness of, for example, 10.0 OOA is formed as an insulating film on the substrate (2) (FIG. 1(a)). A resist pattern is formed thereon (FIG. 1(b)). In this state, it is placed in a wet etching solution (for example, in a 10:I HF solution for 5 minutes) to form a hemispherical hole (FIG. 1(C)).

Next, anisotropic dry etching is performed for several hundred OA to form a wet and dry etched hole (FIG. 1(d)). By repeating the same process one or more times, the diameter of each hole increases toward the top, creating a gentle slope near the bottom of the hole (see Figure 1).
e)). Thereafter, when the resist is removed, a contact hole shaped like a constriction of more than 1 step is formed.

In the above embodiment, wet and dry etching is performed several times, but even if a little anisotropic etching is performed first and then isotropic and anisotropic etching is performed, the same contact as in the above embodiment can be obtained. You get a hole.

Since the contact hole formed as described above has a gentle slope down to the bottom of the contact hole, the coverage with the metal wiring film formed in the next step is improved. Figure 1 (
As shown in f), the film has sufficient thickness even at the bottom of the contact hole, and a highly reliable semiconductor device can be obtained.

Further, in the above embodiment, a BPSG film was assumed as the insulating film, but the effect can be obtained with other insulating films, and the same effect can be obtained even if a Wet etchant or an etchant other than 10:IHFHF is used.

By the way, in the above explanation, the case where the present invention is applied to a contact hole connecting a wiring and a substrate is described.
Needless to say, it can also be used for contact holes connecting interconnections in a semiconductor device with multilayer interconnections.

〔Effect of the invention〕

Since the contact hole according to the present invention is formed as described above, it produces the effects described below.

Since the contact hole has a gentle slope up to the vicinity of the bottom, coverage of the metal wiring film at the bottom of the hole is good in the first step. Furthermore, since the metal wiring film can maintain a sufficient thickness within the contact hole, a highly reliable semiconductor device can be obtained, which in turn leads to a reduction in defective rate.

[Brief explanation of drawings]

FIG. 1(a) to FIG. 1(g) are cross-sectional views showing the manufacturing process of one embodiment of the present invention, and FIG. 1(h) is a metal 2(a) to 2(e), which are cross-sectional views after wiring is formed, are cross-sectional views showing the conventional contact hole manufacturing process.
f) is a cross-sectional view after metal wiring is formed on the contact hole of FIG. 2(e). In the figure, (1) is an insulating film, (2) is a substrate, (3) is a resist, (4) is a wet etching solution, and (5) is a D
ry etching gas, (6) is a metal wiring film. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 2

Claims (3)

[Claims] (1) In a semiconductor device, a contact hole is characterized in that the shape of the hole that connects the wirings or the wirings and the substrate is constricted in two or more stages. (2) The contact hole according to claim 1, wherein the diameter of the contact hole increases toward the top. (3) A method for manufacturing a contact hole, which comprises performing isotropic etching and anisotropic etching two or more times in succession to form the contact hole.