JPH04236450A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the step coverage of a contact hole whose aspect ratio is large. CONSTITUTION:A contact hole is made in a first insulating film 2 which is thinner than the desired thickness of an insulating film; then, a first aluminum film 3 is grown. The aluminum film 3 is removed selectively and an aluminum film 3' is left the inside of the contact hole. A second insulating film 4 having a film thickness which has subtracted the film thickness of the first insulating film 2 form the desired thickness of the insulating film is grown; after that, the part of the contact hole is removed selectively. The first aluminum film 3' revealed on the inside of the contact hole is irradiated with a laser beam and it is melted and flattened. A second aluminum film 5 is grown on a first flattened aluminum film 3' and on the insulating films 2, 4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device,
In particular, the present invention relates to a method for obtaining good step coverage in contact holes with a large aspect ratio. In recent years, as semiconductor devices have become highly integrated, the aspect ratio of contact holes has come to exceed 1, and correspondingly, it has become impossible to obtain satisfactory step coverage with Al wiring.

0002

2. Description of the Related Art The step coverage of Al wiring in a contact hole has been improved by smoothing the shape of the contact hole and increasing the sputtering temperature. However, when the aspect ratio of the contact hole is large, as shown in FIG. 2, good step coverage cannot be obtained using the conventional improvement method.

0003

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a semiconductor device that can obtain good step coverage in a contact hole with a large aspect ratio.

0004

[Means for Solving the Problems] The above-mentioned problem is to solve the above problems in a method of manufacturing a semiconductor device including a step of forming a contact hole having a large aspect ratio. After growing the first insulating film (2), it is selectively removed to form a contact hole, and then a first aluminum film (3) is grown over the contact hole and the first insulating film (2). (b)
selectively removing the first aluminum film (3);
An aluminum film (3') is left inside the contact hole, and (c) a first insulating film (2) is formed to a desired thickness on this aluminum film (3') and the first insulating film (2). ) After growing a second insulating film (4) having a film thickness that is less than Insulating films (2) and (4) having (
d) The first aluminum film (3') exposed inside the contact hole is melted and flattened by laser beam irradiation, and (e) the flattened first aluminum film (3'') and the insulating film (2') are melted and flattened by laser beam irradiation. ), (4) on top of
This problem can be solved by a method characterized by including a step of growing a second aluminum film (5).

[0005]

[Operation] The insulating film and the aluminum film are formed in two stages. In the first step, a first insulating film and a first aluminum film are formed in a conventional manner, but the thickness of the first insulating film is made thinner than a desired thickness. In the second step, a second insulating film is formed on the first insulating film to make the total height of the insulating film surrounding the contact hole a desired height. In this state, the aluminum film inside the contact hole is irradiated with a laser beam to flatten the aluminum film.

Since the bottom of the contact hole is filled with aluminum, the aspect ratio appears to be small. By forming a second aluminum film on this, good step coverage can be obtained.

[0007] The thickness of the first insulating film is preferably half or less of the desired insulating film thickness, and the thickness of the first aluminum film is not less than the thickness of the first insulating film. is preferred.

[0008]

[Example] As shown in FIG. 1(a), a silicon substrate 1
A PSG film with a thickness of 5000 Å was grown thereon by chemical vapor deposition to form the first insulating film 2, and a contact hole with a width of 9000 Å was formed by selective dry etching. Next, sputter aluminum at 250 °C to
The first aluminum film 3 was grown to a thickness of 0 Å.

As shown in FIG. 1(b), the aluminum film on the first insulating film 2 is selectively dry etched.
Leaving the aluminum film 3' only inside the contact hole, next, as shown in FIG. 1(c), a PSG film 4 of 5000 Å was grown in the same manner as the first insulating film 2, and the contact was removed by selective dry etching. The hole part was removed. In this state, the aluminum film 3' exposed inside the contact hole is surrounded by the insulating films 2 and 4 with a total height of 1.0 μm.

[0010] This aluminum film 3' was irradiated with a laser beam to melt the aluminum. Figure 1(d)
As shown in the figure, the depth of the contact hole whose bottom was filled with a flattened aluminum film 3'' was reduced to 4000 Å.
The actual aspect ratio became less than 1. Next, as shown in FIG. 1(e), a second aluminum film 5 was grown on top of the first aluminum film 3 at the same time, and good step coverage could be obtained.

[0011]

According to the present invention, good step coverage can be obtained in a contact hole having an aspect ratio exceeding 1.

0012

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a contact hole forming process according to the present invention.

FIG. 2 is a cross-sectional view of a conventional contact hole.

[Explanation of symbols]

1... Substrate 2... First insulating film 3... First aluminum film 3'... First aluminum film 3'' in the through hole... Flattened first aluminum film 4... Second insulating film 5... second aluminum film

Claims (3)

[Claims] 1. A method for manufacturing a semiconductor device including a step of forming a contact hole with a large aspect ratio, comprising: (a
) After growing a first insulating film (2) thinner than the desired insulating film thickness on the substrate (1), this is selectively removed to form a contact hole, and then the contact hole and the first insulating film are grown. A first aluminum film (3) is grown on the film (2), and (b) the first aluminum film (3) is selectively removed to form an aluminum film (3') inside the contact hole. (c) On this aluminum film (3') and the first insulating film (2), a film having a thickness equal to the desired insulating film thickness minus the film thickness of the first insulating film (2) is formed. After growing the second insulating film (4), the contact hole portion is selectively removed to form insulating films (2) and (4) having a desired total thickness outside the contact hole. (d) The first aluminum film (3') exposed inside the contact hole is melted and flattened by laser beam irradiation, and (e)
A second aluminum film (
5) A method characterized by comprising the step of growing. 2. The method according to claim 1, wherein the first insulating film (2) has a thickness that is less than half the desired insulating film thickness. 3. The method according to claim 1, wherein the first aluminum film (3) has a thickness equal to or greater than that of the first insulating film (2).