JPH05226278A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a contact hole formation method which is capable of reducing a design margin for the contact hole of a semiconductor device. CONSTITUTION:First aluminum 104 is clad on a silicon oxide film 103. There is formed an opening 106 which is not thick enough to reach a semiconductor substrate 101. An aluminum side wall 108 is formed on the sides of the first opening 106. A second opening 109, which reaches a diffusion layer 102, is formed by anisotropic etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a method for forming a contact hole between a semiconductor diffusion layer and a wiring.

[0002]

2. Description of the Related Art A conventional method for forming a contact hole between aluminum and a diffusion layer will be described with reference to FIG.

First, the diffusion layer 3 is formed on the surface of the semiconductor substrate 301.
02 is formed, and a silicon oxide film 303 is formed on the entire surface. Next, a resist 305 is formed. Resist 305
Is a pattern in which there is no part of the portion directly above the diffusion layer 302. Using this resist 305 as a mask, the silicon oxide film 303 is isotropically etched. This etching is stopped before the surface of the semiconductor substrate 301 is exposed to form the first opening 306 [FIG. 3 (a)]. Then, the silicon oxide film 303 is reached until the diffusion layer 302 is reached.
Anisotropic etching is performed to form the second opening 309 [FIG. 3 (b)]. Next, the resist 305 is removed, and aluminum is sputtered and etched to form aluminum 330 serving as a wiring connected to the diffusion layer 302 through the contact hole including the opening 306 and the opening 39 [FIG. 3 (c)].

[0004]

In the conventional contact hole of aluminum and the diffusion layer having the above-mentioned shape,
In order to deposit aluminum having a sufficient thickness in the contact hole by the sputtering method, it is necessary to make the second opening 309 shallow. Therefore, the first opening 3
When 06 is deeply formed by isotropic etching, the first
The diameter of the hole 306 is increased.

Therefore, it is necessary to make the gap between the contact holes sufficiently large. Also,
In the vicinity of the contact hole, it is necessary to secure a sufficiently large distance between the wiring connected to this contact hole and the wiring adjacent to this wiring. As a result, if the contact hole is formed by the conventional method, it becomes a great limitation for high integration.

[0006]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a first film having a property different from that of an interlayer insulating film on an interlayer insulating film formed on a silicon substrate, and an interlayer insulating film. A step of etching a part of a laminated film composed of an insulating film and a first film without reaching the substrate to form a first opening portion, and a second film formed on the entire surface to obtain anisotropy. A step of performing etching to form a sidewall made of the second film inside the first opening; and using the first film and the sidewall as a mask, the interlayer insulating film is etched and removed to the silicon substrate. The method includes a step of forming a second opening at the bottom of the first opening, and a step of forming a conductive film and establishing electrical connection with the silicon substrate.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view in order of steps for explaining a method of manufacturing a semiconductor device according to a first embodiment of the present invention. First, as shown in FIG. 1A, a silicon oxide film 103 is formed on a semiconductor substrate 101 having a diffusion layer 102 formed on its surface.
To form. Next, the first aluminum 104 is deposited on the silicon oxide film 103, and the first aluminum 104 and the silicon oxide film 103 in a predetermined portion of the region immediately above the diffusion layer 102 are etched by a photolithography method to an appropriate depth. The first opening portion 106 is formed.

Next, as shown in FIG. 1B, after removing the resist 105, the second aluminum 107 is formed on the entire surface.
Put on.

Next, as shown in FIG. 1C, a sidewall 108 made of a second aluminum 107 is formed on the side surface of the opening 106 by etching back.

Next, as shown in FIG. 1D, the silicon oxide film 103 is etched using the first aluminum 104 and the sidewall 108 as a mask, and the second
The opening portion 109 is opened to expose the diffusion layer 102.

Next, the third aluminum 110 is deposited, and the diffusion layer 102 and the third aluminum 110 are electrically connected, as shown in FIG. 1 (e).

The thickness of the silicon oxide film 103 is 0.55 μm.
m, the thickness of the first aluminum 104 is 0.1 μm, the diameter of the first opening is 1.0 μm, and the depth is 0.4 μm.
As a result, if the thickness of the second aluminum 107 is set to 1.5 μm by sputtering, the side wall 10
8 has a thickness of 0.2 μm. When the ratio of the diameter of the opening to the depth is 5: 2, the thickness of sputtered aluminum in the opening is 15% of the flat portion. From the above, the second
The diameter of the opening 109 is 0.6 μm and the depth is 0.25 μm.
Therefore, the thickness of the third aluminum formed by sputtering is 15% of the flat portion in the opening. In this way, when the silicon oxide film thickness is 0.55 μm, in order to make the thickness of aluminum 15% of the flat portion, the maximum diameter of the first opening may be 1.0 μm.

On the other hand, when the first opening is formed by wet etching as in the prior art, the maximum diameter must be 1.2 μm. Is more advantageous.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be explained.

First, as shown in FIG. 2A, the diffusion layer 2
A silicon oxide film 203 is formed on the surface of the semiconductor substrate 201 having 02. Next, a first polycrystalline silicon film 214 is deposited on the silicon oxide film 203, and a first opening portion 206 having an appropriate depth is formed by photolithography.

Next, as shown in FIG. 2B, after removing the resist 205, a second polycrystalline silicon film 217 is deposited. Next, as shown in FIG. 2C, the side wall 21 of the second polycrystalline silicon film 217 is formed on the side surface of the opening 206 by etching back the polycrystalline silicon film.
8 is formed.

Next, as shown in FIG. 2D, the second opening portion 209 is opened by etching using the first polycrystalline silicon film 214 and the sidewall 218 of the polycrystalline silicon film as a mask. Then, the diffusion layer 202 is exposed. Next, a tungsten silicide 220 is deposited, and then, FIG.
As shown in, the diffusion layer 202 and the tungsten silicide 220 are electrically connected.

The thickness of the silicon oxide film 203 is 0.7 μm.
m, the thickness of the first polycrystalline silicon film 214 is 0.1 μm
At this time, the diameter of the first opening 206 is 1.0 μm and the thickness of the site wall 218 of the polycrystalline silicon film is 0.2 μm.
When m, the diameter of the second opening can be set to 0.6 μm. Since the depth of the first opening 206 can be 0.55 μm and the depth of the second opening is 0.25 μm, the thickness of the tungsten silicide opening is flat. It will be 15%.

On the other hand, when the first contact is formed by wet etching as in the conventional case, the maximum diameter must be 1.7 μm, and therefore this embodiment is more advantageous than the conventional example from the LSI design margin. Is.

[0021]

As described above, according to the present invention, the thickness of the sidewall of the first opening can be freely determined by changing the film thickness of the second film. Accordingly, the sidewall can be used as a mask to freely change the diameter of the second opening, conversely, the diameter of the first opening can be freely set for a constant second opening diameter. Since it can be changed to, it is possible to reduce the design margin including the contact hole and facilitate high integration.

[Brief description of drawings]

1A to 1D are cross-sectional views in order of processes for explaining a first embodiment of the present invention.

2A to 2D are cross-sectional views in order of the steps, for explaining the second embodiment of the present invention.

3A to 3D are cross-sectional views in order of processes for explaining a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 101, 201, 301 Semiconductor substrate 102, 202, 302 Diffusion layer 103, 203, 303 Silicon oxide film 104 First aluminum 105, 205, 305 Resist 106, 206, 306 First opening 107 Second aluminum 108 Aluminum sidewalls 109, 209, 309 Second openings 110 Third aluminum 214 First polycrystalline silicon film 217 Second polycrystalline silicon film 218 Polycrystalline silicon sidewall 220 Tungsten silicide 330 Aluminum

Claims (1)

[Claims] 1. A step of forming a first film having a property different from that of the interlayer insulating film on an interlayer insulating film formed on a silicon substrate, and comprising the interlayer insulating film and the first film. A step of anisotropically etching a part of the laminated film to a depth that does not reach the silicon substrate to form a first opening, and a second film formed on the entire surface and anisotropically etched, Forming a sidewall made of the second film inside the first opening; and removing the interlayer insulating film up to the silicon substrate by using the first film and the sidewall as a mask Then, a step of forming a second opening in the bottom of the first opening, and a step of forming a conductive film and establishing electrical connection with the silicon substrate are provided. Production method.