KR0155787B1 - Formation method of contact hole in semiconductor device - Google Patents

Abstract

A method of forming a contact window is described. This is a first step of forming a transistor on a semiconductor substrate, a second step of forming a first insulating film on the entire surface of the resultant, a third step of forming a first photosensitive film on the first insulating film, and a second insulating film on the first photosensitive film. A fourth process of forming a second photoresist film, a fifth process of forming a second photoresist film on the second insulating film, a sixth process of forming a second photoresist film pattern by removing the second photoresist film in a region where a buried contact window is to be formed, and the second process Forming a first photoresist pattern by removing the second photoresist pattern, and removing the first photoresist layer in a region where an buried contact window is to be formed; and removing the second photoresist pattern by using a second photoresist pattern as an etching mask. An eighth step, a ninth step of forming a third insulating film on the entire surface of the resultant, and a tenth step of forming a buried contact window in the first insulating film by using the third insulating film and the second insulating film. . A contact window of a smaller size than the minimum feature size can be formed, thereby facilitating the integration of the memory device.

Description

Method of forming a buried contact window in a semiconductor memory device

1A and 1B are cross-sectional views illustrating a buried contact window forming method of a semiconductor memory device according to a conventional method.

2A and 2G are cross-sectional views illustrating a method for forming a buried contact window in a semiconductor memory device according to a first embodiment of the present invention.

3A and 3B are cross-sectional views illustrating a method of forming a buried contact window in a semiconductor memory device according to a second embodiment of the present invention.

4A and 4B are cross-sectional views illustrating a method for forming a buried contact window in a semiconductor memory device according to a third embodiment of the present invention.

5A and 5D are cross-sectional views illustrating a buried contact window forming method of a semiconductor memory device in accordance with a fourth embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor memory device, and more particularly, to a method of forming a buried contact window of a semiconductor memory device in which the size of the buried contact window is formed to a size less than or equal to the limit resolution.

As the degree of integration of semiconductor memory devices increases, the size of the contact window for connecting the upper conductive layer and the lower conductive layer becomes smaller.

In particular, in the case of DRAM, in order to form a storage electrode connected to the source of the transistor and a bit line connected to the drain, a contact window for the same must be formed on the source and the drain. The problem that must be formed to a size below the resolution occurs.

To solve this problem, presently, self-aligning contact windows exposing the source and drain are then landed on these exposed sources and drains for easy connection with story electrodes and bit lines. A method of forming a pad has been proposed.

1A and 1B are cross-sectional views illustrating a buried contact window forming method of a semiconductor memory device according to a conventional method.

After forming a transistor composed of the source 16, the drain 18, and the gate electrode 14 on the semiconductor substrate 10, a self-aligning method for exposing the contact window exposing the source 16 and the drain 18 to the surface. To form. Subsequently, polysilicon is deposited / patterned on the entire surface of the resultant to form a first pad 20 to be connected to the source 16 and a first pad 22 to be connected to the drain 18. The first insulating film 24 is formed by forming the first and second pads 20 and 22 and then applying an insulating material such as an oxide film or BPSG (Boro-phosphorus Silicate Glass) to the entire surface of the resultant. Next, a photoresist is applied / developed on the first insulating film 24 to form a pattern 26 for forming a buried contact window for connecting the story electrode to the source 16 (FIG. 1A).

An anisotropic etching process using the pattern 26 as an etch mask and the first insulating film 24 as an etch target, by partially removing the first insulating film stacked on the first pad 20 to form a buried contact window ( 1) is formed (FIG. 1b).

According to the above-described method of easily connecting the storage electrode and the source through the buried contact window by forming a pad connected to the source and forming a buried contact window on the pad, the buried contact window is formed on the pad. The process margin for forming a buried contact window can be increased.

That is, when the buried contact window is directly formed on the source, the gate electrode may be exposed to the surface through the sidewall of the buried contact window (see dotted line in FIG. 1B), but as described above, In the case of forming the buried contact window, the exposure phenomenon of the gate electrode does not occur by the pad layer formed to have a size larger than the gap between the gate electrodes (see FIG. 1B).

However, as the degree of integration of a memory device increases, various elements are formed by the formation of a three-dimensional structure of wiring (which may be formed by single layer wiring when the density is small, or by forming multilayer wiring when the degree of integration is large). It is densely formed on the phase. Therefore, it is important to reduce the size of not only the contact window but also other elements such as wiring to secure process margin.

An object of the present invention is a method of forming a buried contact window of a semiconductor memory device for forming a buried contact window of a size smaller than the minimum feature size.

In order to achieve the above object, a buried contact window forming method of a semiconductor memory device according to the present invention comprises: a first step of forming a transistor on a semiconductor substrate; Forming a first insulating film on the entire surface of the resultant material; A third step of forming a first photosensitive film on the first insulating film; A fourth step of forming a second insulating film on the first photosensitive film; A fifth step of forming a second photosensitive film on the second insulating film; A sixth step of forming a second photoresist film pattern by removing the second photoresist film in the region where the buried contact window is to be formed; A seventh step of etching the second insulating layer using the second photoresist pattern as an etching mask; An eighth step of removing the second photoresist pattern and simultaneously removing the first photoresist layer in a region where the buried contact window is to be formed to form a first photoresist pattern; A ninth step of forming a third insulating film on the entire surface of the resultant material; And a tenth step of forming a buried contact window in the first insulating layer by using the third insulating layer and the second insulating layer.

In the method for forming a buried contact window of a semiconductor memory device according to the present invention, it is preferable to further include a step of forming a pad for connecting the source and the drain of the transistor after the first step.

In the buried contact window forming method of a semiconductor memory device according to an embodiment of the present invention, the tenth step is anisotropically etching the third insulating film to form a spacer on the sidewall of the first photosensitive film pattern and the second insulating film And etching the spacer and simultaneously etching the first insulating layer to form a buried contact window.

In the method of forming a buried contact window of a semiconductor memory device according to another embodiment of the present invention, it is preferable to further include forming a first material layer on the first insulating layer after the second step. In this case, the tenth step may include forming a spacer on the sidewalls of the first photoresist pattern by etching the third insulating layer, and etching the first material layer by using the spacer and the second insulating layer as an etching mask. The process of forming a pattern and the process of forming a buried contact window by etching the first insulating layer using the first material layer pattern as an etching mask are preferred.

In the method for forming a buried contact window of a semiconductor memory device according to the present invention, the material constituting the insulating films is preferably a material having an etching rate different from that of the material constituting the first material layer for a predetermined etching. More preferably, an oxide is used as a material constituting the insulating layers, and one of polycrystalline silicon and silicon nitride is used as a material constituting the first material layer.

In addition, a method for forming a buried contact window of a semiconductor memory device according to the present invention for achieving the above object includes a first step of forming a transistor on a semiconductor substrate; Forming a first insulating film on the entire surface of the resultant material; A third step of forming a first material layer on the first insulating film; A fourth step of forming a first photosensitive film on the insulating film; A fifth process of forming a first photoresist film pattern by removing the first photoresist film in an area where a buried contact window is to be formed; A sixth step of etching the first material layer exposed to the surface through the first photoresist pattern; And a seventh step of forming a buried contact window by etching the first insulating layer using the inclined etched first material layer as an etch mask.

A method of forming a buried contact window in a semiconductor memory device according to an embodiment of the present invention, comprising: forming a second insulating film on a resultant after the fourth step; forming a second photosensitive film on the second insulating film The method may further include forming a second photoresist layer pattern by removing the second photoresist layer of the portion where the buried contact window is to be formed, and etching the second insulation layer by using the second photoresist layer pattern as an etching mask.

At this time, in the seventh process, it is preferable that the second insulating film is removed together with the first insulating film.

In the method for forming a buried contact window of a semiconductor memory device according to the present invention, the material constituting the insulating films is preferably a material having an etching rate different from that of the material constituting the first material layer for a predetermined etching. More preferably, an oxide is used as a material constituting the insulating layers, and one of polycrystalline silicon and silicon nitride is used as a material constituting the first material layer.

Therefore, according to the method of forming a buried contact window of the semiconductor memory device according to the present invention, a material layer having a minimum feature size pattern for forming a contact window and having a etch rate similar to that of an etch target for a predetermined etching on the resultant After forming, the buried contact window smaller than the minimum feature size may be formed by etching the object to be etched simultaneously with the material layer by anisotropic etching.

Hereinafter, with reference to the accompanying drawings, it will be described in detail an embodiment of the present invention. In the figures continuously introduced, the same reference numerals as those described in FIGS. 1A and 1B mean the same parts.

Example 1

2A to 2G are cross-sectional views illustrating a buried contact window forming method of a semiconductor memory device according to a first embodiment of the present invention.

First, FIG. 2A illustrates a process of forming transistors and landing pads 20 and 22, which is a first process of forming a field oxide film 12 for limiting the semiconductor substrate 10 to an active region and an inactive region, A second step of forming a gate electrode 14 by laminating a gate oxide film, a gate electrode forming material and an oxide film on the entire surface of the resultant, a third process of doping impurity ions at a low concentration, and applying an oxide film on the entire surface of the resultant Thereafter, anisotropic etching is performed to form a spacer on the sidewall of the gate electrode 14 to expose the region where the source and the drain of the transistor are to be formed on the surface. And a fifth process of forming the drain 18, depositing a conductive material such as polycrystalline silicon on the entire surface of the resultant, and then patterning the conductive material to be connected to the source 16. The sixth process of forming the first landing pad 20 and the second landing pad 22 connected to the drain 18 and the entire surface of the resultant, for example, by applying an oxide film or BPSG, the first insulating film having a flat surface Proceeds to a seventh step of forming (24).

FIG. 2B illustrates a process of forming the first photoresist film 28, the second insulating film 30, and the second photoresist film pattern 32, which are formed on the first insulation film 24, for example, a photoresist such as a photoresist. A first step of applying a material to form a first photosensitive film 28, a second step of forming a second insulating film 30 by applying an insulating material such as, for example, an oxide on the first photosensitive film 28, A third step of forming a second photoresist film by applying a photoresist such as, for example, a photoresist on the second insulation film, and developing the second photoresist film to open the second insulation film in a portion where a buried contact window is to be formed; The process proceeds to a fourth step of forming the two photoresist pattern 32.

FIG. 2C illustrates a process of forming the second insulating film pattern 31 and the first photoresist film pattern 29, which is an anisotropic etching using the second photoresist film pattern as an etching mask and the second insulating film as an etching target. Performing a step to remove the first step of forming the second insulating film pattern 31 and the second photosensitive film pattern, and simultaneously removing the first photosensitive film exposed to the surface to form the buried contact window. It proceeds to the 2nd process of forming the 1st photosensitive film pattern 29 which exposes 24 to the surface.

FIG. 2D illustrates a process of forming the third insulating film 34, which is formed by applying an insulating material such as an oxide to the entire surface of the resultant film on which the first photoresist pattern 29 is formed.

FIG. 2E shows a process of forming the spacer 34a, which is formed by performing anisotropic etching using the third insulating film as an etching target on the entire surface of the resultant.

FIG. 2F illustrates a process of forming the buried contact window 1, which is the result of an anisotropic etching using the second insulating film pattern, the spacer, and the first insulating film (31, 34a, and 24 in FIG. 2e) as etching targets. It is formed on the front side.

In one embodiment of the present invention, since the second insulating film pattern, the spacer, and the first insulating film are all formed of an oxide film, the second insulating film pattern and the spacer are removed at the same time, so that the second insulating film pattern and the spacer are removed. Removed. In this case, since the first insulating layer is removed by using the second insulating layer and the spacer as an etching mask, the buried contact window 1 is twice as small as the spacer thickness than the gap between the first photoresist pattern 29.

2g shows the result after removing the first photoresist pattern.

Therefore, according to the first embodiment of the present invention, the size of the buried contact window can be made smaller than the minimum feature size (usually, the second photosensitive film pattern for forming the buried contact window is formed with the minimum feature size).

Example 2

3A and 3B are cross-sectional views illustrating a method for forming a buried contact window in a semiconductor memory device according to a second embodiment of the present invention.

After the seventh step of FIG. 2A is performed to form the first insulating film 24, a material having an etching rate different from that of the material forming the first insulating film for a predetermined etching on the entire surface of the resultant, for example, polysilicon And forming a first material layer 36 by applying any one of silicon nitride, and then the process of forming the third insulating film 34 is the same as the process up to FIG. 2d. (Figure 3a).

Subsequently, an anisotropic etching is performed using the third insulating layer as an etching target to form a spacer on the sidewall of the first photoresist pattern 29, and the first material using the second insulating layer pattern 31 and the spacer as an etching mask. A second process of etching the layer 36 to form a first material layer pattern 37, a third process of removing materials stacked on the first material layer pattern 37, and the first material layer pattern The buried contact window 1 is formed by proceeding to the fourth step of performing anisotropic etching using the 37 as an etching mask and the first insulating film 24 as an etching target (FIG. 3B).

Example 3

4A and 4B are cross-sectional views illustrating a method for forming a buried contact window in a semiconductor memory device according to a third embodiment of the present invention.

FIG. 4A illustrates a process of forming the first material layer pattern 37a, which is performed up to the seventh process of FIG. 2A to form the first insulating layer 24, and then on the resultant, for a predetermined etching. On the first material layer and the first process of forming a first material layer by applying a material having an etching different from the material constituting the first insulating layer, for example, any one of polycrystalline silicon and silicon nitride The second process and the first photoresist pattern 29 are formed by coating / developing the same photoresist of photoresist to form a first photoresist pattern 29 for exposing the first material layer on the surface where the buried contact window is to be formed. The first material layer exposed to the surface is obliquely etched to proceed to the third process of forming a first material layer pattern 37a having a window which becomes smaller as the direct line is lowered downward.

4B illustrates a process of forming the buried contact window 1, which is a first process of removing materials stacked on the first material layer pattern 37a and the first material layer pattern 37a. Is an etching mask and anisotropic etching is performed using the first insulating layer 24 as an etching target.

According to the third embodiment of the present invention, the first material layer is inclined etched to form a first material layer pattern having a diameter smaller than the diameter of the first photoresist pattern, and the first insulating layer is formed as an etch mask. By etching, the buried contact window smaller than the minimum feature size can be formed.

Example 4

5A and 5D are cross-sectional views illustrating a buried contact window forming method of a semiconductor memory device in accordance with a fourth embodiment of the present invention.

After the first process shown in FIG. 4A is performed to form the first photosensitive film 28, an insulating material such as, for example, an oxide is coated on the first photosensitive film 28 to form a second insulating film 30. After forming a second photoresist film by applying a photoresist such as, for example, a photoresist on the second insulating film, the second photoresist film having a window for exposing the second insulating film 30 in the portion where the buried contact window is to be formed to the surface is developed. The pattern 32 is formed (FIG. 5A).

The second insulating film pattern 31 is formed by etching the second insulating film by using the second photoresist pattern 32 as an etch mask, and the etching process using the second photoresist pattern 32 and the first photoresist film as an etching target. The first photosensitive film pattern 29 having the window exposed to the surface of the first material layer in the region where the buried contact window is to be formed is formed. Subsequently, the first material layer is inclined and etched in the same manner as described in FIG. 4A to form the first material layer pattern 37a (FIG. 5B).

An anisotropic etching using the second insulating film pattern and the first insulating film as an object to be etched is performed on the entire surface of the resultant to form a buried contact window 1 and to remove materials stacked on the first insulating film 24 (the 5c and 5d)

Therefore, according to the buried contact window forming method of the semiconductor memory device according to the present invention, it is possible to form a contact window smaller than the minimum feature size, thereby facilitating the improvement of the integration degree of the memory device.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical idea of the present invention.

Claims (12)

Forming a transistor on a semiconductor substrate; Forming a first insulating film on the entire surface of the resultant material; A third step of forming a first photosensitive film on the first insulating film; A fourth step of forming a second insulating film on the first photosensitive film; A fifth step of forming a second photosensitive film on the second insulating film; A sixth step of forming a second photoresist film pattern by removing the second photoresist film in the region where the buried contact window is to be formed; A seventh step of etching the second insulating layer using the second photoresist pattern as an etching mask; An eighth step of removing the second photoresist pattern and simultaneously removing the first photoresist layer in a region where the buried contact window is to be formed to form a first photoresist pattern; A ninth step of forming a third insulating film on the entire surface of the resultant material; And a tenth step of forming a buried contact window in the first insulating film by using the third insulating film and the second insulating film. The method of claim 1, further comprising: forming a pad connecting the source and the drain of the transistor after the first step. The method of claim 1, wherein the tenth step is performed by anisotropically etching a third insulating layer to form a spacer on the sidewalls of the first photoresist pattern, and etching the second insulating layer and the spacer and simultaneously etching the first insulating layer. The buried contact window forming method of the semiconductor memory device, characterized in that the step of forming a buried contact window. The method of claim 1, further comprising forming a first material layer on the first insulating layer after the second process. The method of claim 4, wherein the tenth step comprises: etching the third insulating layer to form a spacer on sidewalls of the first photoresist layer, and etching the first material layer using the spacer and the second insulating layer as an etch mask. Forming a buried contact window by forming a buried contact window by etching the first insulating layer using the first material layer pattern as an etch mask and etching the first insulating layer Way. The semiconductor according to any one of claims 1 to 4, wherein the material constituting the insulating layers is a material having an etching rate different from that of the material constituting the first material layer for a predetermined etching. Method of forming a buried contact window of a memory device. The buried contact of the semiconductor memory device according to claim 5, wherein an oxide is used as a material for forming the insulating layers, and one of polycrystalline silicon and silicon nitride is used as a material for the first material layer. How to form a window. Forming a transistor on a semiconductor substrate; Forming a first insulating film on the entire surface of the resultant material; A third step of forming a first material layer on the first insulating film; A fourth step of forming a first photosensitive film on the insulating film; A fifth process of forming a first photoresist film pattern by removing the first photoresist film in an area where a buried contact window is to be formed; A sixth step of etching the first material layer exposed to the surface through the first photoresist pattern; And forming a buried contact window by etching the first insulating layer using the inclined etched first material layer as an etch mask. The method of claim 7, wherein after the fourth process, forming a second insulating film on the resultant, forming a second photosensitive film on the second insulating film, and removing the second photosensitive film in a portion where the buried contact window is to be formed. And forming a second photoresist pattern, and etching the second insulation layer using the second photoresist pattern as an etch mask. The method of claim 8, wherein the second insulating layer is removed together with the first insulating layer in the seventh process. The method of claim 7, wherein the material constituting the insulating layers is a material having an etching rate different from that of the material constituting the first material layer for a predetermined etching. . 12. The buried contact of the semiconductor memory device according to claim 10, wherein an oxide is used as a material for forming the insulating films, and one of polycrystalline silicon and silicon nitride is used as a material for the first material layer. How to form a window.