KR100231851B1 - A contact hole formation method of semiconductor - Google Patents

Abstract

The present invention relates to a method for forming contact holes in a semiconductor device using wet and dry etching processes. In the method of forming a contact hole on an insulating film having an interlayer conductive layer formed on a silicon substrate, forming a contact hole on an oxide film. Forming a photoresist pattern using a mask for etching, followed by wet etching to remove a portion of the oxide layer, a second step of forming a low temperature oxide layer on the entire structure, and etching a low temperature oxide layer by an oxide etch back process. The third step of removing the oxide film by dry etching again after the photoresist film is exposed, the wet etching of the oxide film again using an oxide etching solution having a lower etching speed in the lateral direction than the etching speed in the vertical direction And a fifth step of forming a contact hole by dry etching the oxide layer again. When the contact is formed by depositing a metal after the formation of the contact hole, it is possible to prevent a short circuit between the other conductive layers in the lower part, and to reduce the aspect ratio, thereby obtaining an effect of forming a contact without forming an empty space inside the contact. .

Description

Contact hole formation method of semiconductor device

1 is a cross-sectional view of a contact hole forming process according to an embodiment of the present invention.

2 is a cross-sectional view of a contact hole forming process according to another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1 silicon substrate 2 oxide film

3: photosensitive film 4: low temperature oxide film

5: low temperature polysilicon film 10: polysilicon layer

The present invention relates to a method of forming contact holes in a semiconductor device using wet and dry etching processes of the present invention.

In general, as the degree of integration of the device increases, the size of the contact decreases, thereby increasing the aspect ratio after contact hole formation.

The conventional method for forming the contact hole is a dry etching method.

However, in the dry etching method, when forming a contact by depositing a metal after forming a contact hole, an aspect ratio increases, and thus, a step coverage characteristic is deteriorated, resulting in a void in the contact.

Another conventional method is a method of mixing wet etching and dry etching.

However, in the conventional method, as the degree of integration increases, first, the gap between the contacts becomes narrow, and second, the gap between the contact portion and another conductive layer, such as a polysilicon film, also becomes narrow. Therefore, when the wet etching target is increased, the wet etching target cannot be enlarged because the side and the vertical region are isotropically etched during the wet etching to cause a short circuit between the contact and the other conductive layer.

The present invention devised to solve the above problems is to provide a method for forming a contact hole of a semiconductor device to reduce the aspect ratio to improve step coverage when forming a contact.

In order to achieve the above object, the contact hole forming method of the present invention is a method of forming a contact hole on an insulating film having an interlayer conductive layer formed on a silicon substrate, and forming a photoresist pattern as a mask for forming a contact hole on an oxide film, The first step of removing part of the oxide film by wet etching, the second step of forming a low temperature oxide film on the entire structure, and etching the low temperature oxide film by an oxide etch back process to expose the photoresist film and then dry again. A third step of partially removing the oxide layer by etching, a fourth step of wet etching the oxide layer again using an oxide etching solution having an etch rate in the lateral direction lower than an etching rate in the vertical direction, and dry etching the oxide layer again And a fifth step of forming a contact hole.

In addition, the contact hole forming method of the present invention is a method for forming a contact hole on an insulating film having an interlayer conductive layer formed on a silicon substrate, wherein a photoresist pattern is formed as a mask for forming a contact hole on an oxide film, and then wet etching to form the contact hole. A first step of removing part of the film, a second step of forming a low temperature polysilicon film on the entire structure, and a photoetch film by etching by a poly etch back process, and then a third step of dry etching, poly And a fourth step of wet etching again using the silicon etching solution and a fifth step of forming a contact hole by dry etching again.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

First, a method of forming a contact hole according to an embodiment of the present invention will be described with reference to FIG. 1, where 10 represents a polysilicon layer.

FIG. 1A is a cross-sectional view of the photosensitive film pattern 3 formed as a mask for forming contact holes on the oxide film 2 on which the polysilicon layer 10, which is an interlayer conductive layer, is formed on the silicon substrate 1.

FIG. 1B is a cross-sectional view of the oxide film 3 partially removed by wet etching.

FIG. 1C is a cross-sectional view of the low temperature oxide film 4 formed over the entire structure. In this case, the low temperature oxide film should be able to be formed at a low temperature enough to be used with the photoresist film and to be flattened.

1 (d) is a cross-sectional view after the photoresist film 3 is exposed by etching the low-temperature oxide film 4 on the surface by an oxide etch back process and then dry etching again to remove a portion of the oxide film 2. .

FIG. 1 (e) is a cross-sectional view after wet etching the oxide film 2 again using a buffered oxide etchant (BOE) solution which is an oxide film etching solution. In this case, the wet etching profile as a whole may be made deeper in the vertical direction than the side by preventing the etching of the side surface of the low-temperature oxide film 4 toward the side.

FIG. 1 (f) is a cross-sectional view of the oxide film 2 being dry-etched again to form contact holes.

Next, another embodiment of the present invention will be described with reference to FIG. 2.

2 (a) and 2 (b) show a photosensitive film pattern 3 for forming contact holes on an oxide film 2 having a polysilicon layer 10 as an interlayer conductive layer formed on a silicon substrate 1. Then, a cross-sectional view of the oxide film 3 partially removed by wet etching is the same as the process according to the present invention.

FIG. 2C is a cross-sectional view of the low-temperature polysilicon film 5 formed on the entire structure. At this time, the low temperature polysilicon film should be formed at a low temperature enough to be used with the photosensitive film.

In FIG. 2 (d), the photosensitive film 3 is exposed by etching the low-temperature polysilicon film 5 on the surface by a poly etch back process, and then dry-etched again to etch the target in the vertical direction rather than the lateral direction. To make it bigger.

FIG. 2 (e) is a cross-sectional view after wet etching again using a phosphoric acid (H ₃ PO ₄ ) solution, which is a polysilicon etching solution. At this time, the low-temperature polysilicon film 5 on the side may be made deeper in the vertical direction than the side of the wet etching profile as a whole by preventing the etching toward the side.

FIG. 2 (f) is a cross-sectional view of the contact film formed by dry etching the oxide film 2.

In the method of forming a contact hole according to the present invention, the contact hole is formed by depositing a metal after the formation of the contact hole, thereby preventing a short circuit between other conductive layers in the lower portion, and reducing the aspect ratio so that the contact is not formed inside the contact. It is possible to obtain the effect that can form.

Claims (6)

In the method for forming a contact hole on an insulating film on which an interlayer conductive layer is formed on a silicon substrate during a manufacturing process of a semiconductor device, a photosensitive film pattern 3 is formed as a mask for forming contact holes on the oxide film 2, and then wet etching. The first step of removing the oxide film 2 partially, the second step of forming the low temperature oxide film 4 on the entire structure, and etching the low temperature oxide film 4 by an oxide etch back process. 3) exposing and then dry etching again to remove part of the oxide film 2, the oxide film 2 using an oxide film etching solution whose etching speed in the lateral direction is slower than that in the vertical direction. And a fifth step of wet etching again, and a fifth step of forming a contact hole by dry etching the oxide film (2) again. The method of claim 1, wherein the low temperature oxide film (4) of the second step is formed at a low temperature enough to be used together with the photosensitive film. The method of claim 1, wherein the oxide etching solution of the fourth step is a polysilicon, which is a buffered oxide etchant (BOE) solution or a barrier material. In the method for forming a contact hole on an insulating film having an interlayer conductive layer formed on a silicon substrate during a manufacturing process of a semiconductor device, the photosensitive film pattern 3 is formed by using a mask for forming a contact hole on the oxide film 2, and then wet. The photoresist film 3 is etched by etching the first step of removing part of the oxide film 2 by etching, the second step of forming the low temperature polysilicon film 5 on the entire structure, and the poly etch back process. And exposing and then dry etching again, a fourth step of wet etching again using a polysilicon etching solution, and a fifth step of forming dry contact holes by dry etching. Method for forming contact hole of device. 5. The method of claim 4, wherein the low temperature polysilicon film (5) of the second step is formed at a temperature low enough to be used together with the photosensitive film. The method of claim 4, wherein the polysilicon etching solution of the fourth step is a phosphoric acid (H ₃ PO ₄ ) solution.