JPH06244129A - Method for forming fine contact hole of semiconductor element - Google Patents

Abstract

PURPOSE: To provide a method for forming contact holes having width smaller than the patterns of an etching mask. CONSTITUTION: In the method for forming fine contact holes on a highly integrated semiconductor element such a DRAM, SRAM and an ASIC requiring fine patterns, a polysilicon pad 10A acting as an etching barrier is formed on the sidewall of a silicon nitride film 8 at the time of etching for forming contact holes, so that fine contact holes smaller than contact mask patterns can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a fine contact hole in a highly integrated semiconductor device such as DRAM, SRAM, ASIC, etc. which requires a fine pattern.

[0002]

2. Description of the Related Art Generally, as the degree of integration of semiconductor devices increases, the minimum line width on a chip decreases accordingly.
The area of the unit cell is also reduced. Due to such a decrease in the minimum line width, the distance between the lines is also reduced, so that it is difficult to form a contact region between the lines.

The conventional method of forming a fine contact hole uses a self align contact method. However, if the topology is severe, the contact hole has a large aspect ratio and the etching process is difficult. In the case of a DRAM cell, a short circuit between a word line and a bit line, a short circuit between a word line or a bit line and a charge storage electrode, a short circuit due to a gap, an increase in contact resistance, etc.
We have experienced numerous process difficulties.

To solve the above problems, the present invention forms a polysilicon pad on the sidewall of an insulating film that acts as a barrier when forming a contact hole of a highly integrated semiconductor device having a high topology and a fine pattern, and the same polysilicon pad is formed. It is an object of the present invention to provide a method for forming a contact hole having a width smaller than the pattern of the etching mask by allowing the film to act as an etching barrier together with the insulating film.

[0005]

In order to achieve the above object, a method of forming a fine contact hole of a semiconductor device according to the present invention comprises a step of depositing an oxide film on a surface of a semiconductor substrate including a contact region, A step of depositing an insulating film having a low etching rate on the surface of the oxide film, a photosensitive film is applied on the surface of the insulating film, and then a desired pattern is formed by a masking process to remove a part of the oxide film by etching. A step of removing the photosensitive film remaining on the oxide film, a step of depositing a polysilicon film with a predetermined thickness on the surface of the oxide film and the insulating film, a portion of which is removed by etching. Forming a polysilicon pad on a sidewall of the insulating film by anisotropically etching the polysilicon film to expose the oxide film without using a separate mask; and Characterized by comprising the step of forming the contact hole by using a silicon pad as an etching barrier etching the oxide film of the contact hole area.

[0006]

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

First, as shown in FIG. 1, the semiconductor substrate 1
A device isolation oxide film 2, a gate oxide film 3, a word line 4 as a gate electrode, a source electrode 6A, and a drain electrode 6 on the surface of
After forming B, the oxide film 5 is deposited.

Next, as shown in FIG. 2, an oxide film 7 is further deposited on the surface of the oxide film 5, and a silicon nitride film 8 having a smaller etching rate than the oxide film 7 is deposited on the surface of the oxide film 7. Then
After applying the photosensitive film 9 on the surface of the silicon nitride film 8, a desired pattern is formed in a masking process.

Next, as shown in FIG. 3, the silicon nitride film 8 is dry-etched using the photosensitive film pattern 9 and a part of the oxide film 7 is wet-etched.

Thereafter, as shown in FIG. 4, the photosensitive film 9 is removed and a polysilicon film 10 is deposited on the exposed surface of the silicon nitride film 8 and the oxide film 7 which is partially etched. . Next, as shown in FIG. 5, the oxide film 7 and the oxide film 5 in the contact hole region are sequentially etched to form a contact hole. At this time, the polysilicon pad 10A formed on the side wall of the silicon nitride film 8 acts as an etching barrier to form a contact hole having a width smaller than the pattern of the contact hole mask.

[0011]

According to the present invention, word lines, bit lines, etc., which are frequently generated by forming contact holes with very small line intervals in the manufacturing process of highly integrated semiconductor devices by a relatively simple process. It is possible to give a margin to the process so as to prevent a short circuit with the conductive layer. Therefore, the present invention can easily form a fine contact hole of a highly integrated semiconductor device, and thus has an effect of improving not only the yield of the device but also the reliability of the device.

[Brief description of drawings]

FIG. 1 is a diagram showing a first step of a method for forming a fine contact hole in a semiconductor device according to the present invention.

FIG. 2 is a diagram showing a second step of the method for forming a fine contact hole of a semiconductor device according to the present invention.

FIG. 3 is a diagram showing a third step of the method for forming a fine contact hole in a semiconductor device according to the present invention.

FIG. 4 is a diagram showing a fourth step of the method for forming a fine contact hole of a semiconductor device according to the present invention.

FIG. 5 is a diagram showing a fifth step of the method for forming a fine contact hole in a semiconductor device according to the present invention.

FIG. 6 is a diagram showing a sixth step of the method for forming a fine contact hole in a semiconductor device according to the present invention.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... Element isolation oxide film, 3 ... Gate oxide film, 4 ... Word line, 5, 7 ... Oxide film, 6A ... Source electrode, 6B ... Drain electrode, 8 ... Silicon nitride film, 9 ... Photosensitive film 10 ... Polysilicon film, 10A ... Polysilicon pad

Front Page Continuation (72) Inventor Don Yar Kyum Republic of Korea Kyun Sang Buk De Chun Do Kun Lee Seomyun Sinchon 2-Dong 462

Claims (3)

[Claims] 1. A method of forming a fine contact hole in a manufacturing process of a semiconductor device, comprising a step of depositing an oxide film on a surface of a semiconductor substrate including a contact region, and an insulating film having an etching rate smaller than that of the oxide film. A step of depositing on the surface of the oxide film; a step of applying a photosensitive film on the surface of the insulating film, and then forming a desired pattern in a masking step to remove a part of the oxide film by etching; A step of removing the photoresist film remaining on the surface, a step of vapor-depositing a polysilicon film with a predetermined thickness on the surfaces of the oxide film and the insulating film, a part of which has been removed by etching, using a separate mask. First, a step of forming a polysilicon pad on the sidewall of the insulating film by anisotropically etching the polysilicon film to expose the oxide film, and etching the insulating film and the polysilicon pad A method of forming a fine contact hole in a semiconductor device, comprising the step of etching the oxide film in the contact hole region to form a contact hole by using it as a barrier. 2. The method for forming a fine contact hole in a semiconductor device according to claim 1, wherein the insulating film is a silicon nitride film. 3. The method for forming a fine contact hole of a semiconductor device according to claim 1, wherein the oxide film is deposited in two layers.