KR100231598B1 - Method for forming contact hole of semiconductor device - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor device, wherein a stacked structure of a word line conductive layer / silicide film / interlayer insulating film is deposited on a semiconductor substrate to a predetermined thickness, and the interlayer insulating film, the silicide film and the word line conductive layer are contacted. By sequentially etching using a mask, an interlayer insulating film pattern, a silicide film pattern, and a conductive layer pattern for word lines are formed, and the silicide film forms an undercut under the interlayer insulating film, and then the interlayer insulating pattern, the silicide film pattern, and the word An insulating layer spacer is formed on the sidewalls of the line conductive layer pattern, a lower insulating layer is formed to planarize the entire upper surface of the semiconductor substrate, and then the semiconductor substrate is exposed by self-aligned contact etching using the contact mask. Forms contact holes but is stable even when misalignment of contact masks occurs By forming a contact hole, the technology improves the yield and productivity of the semiconductor device, improves the characteristics and reliability of the semiconductor device, and accordingly, enables high integration of the semiconductor device.

Description

Contact hole formation method of semiconductor device

1A to 1F are cross-sectional views illustrating a method for forming a contact hole in a semiconductor device according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

11: conductive layer for word line 13: tungsten silicide film

15: interlayer insulating film 17: undercut

19 nitride layer 21 lower insulating layer

23: photoresist pattern 25: contact hole

40: semiconductor substrate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a contact hole in a semiconductor device. In particular, a contact hole having a size of 0.3 μm or less is formed by a self-aligned contact process that can secure an overlap margin. It is related with the technique which can form an element.

Among semiconductor memory devices, a DRAM forms a gate electrode on a semiconductor substrate and forms a contact hole exposing a source / drain junction formed between the gate electrode and the gate electrode, and then connected to the source / drain junction through the contact hole. Bit lines and capacitors were formed.

Initially, the width between the gate electrodes was wide so that there was almost no short circuit between the gate electrode and bit line or the gate electrode and capacitor.

However, as semiconductor devices are integrated, a short circuit between conductive layers occurs to form oxide spacers on sidewalls of the gate electrode.

As the semiconductor device is highly integrated, insulation of the gate electrode cannot be sufficiently performed with only the oxide film spacer, thereby forming contact holes formed between the gate electrodes and having nitride spacers formed on sidewalls.

Here, the self-aligned contact hole forming process may be performed by using an etching selectivity difference when an etching selectivity difference between an oxide film and an oxide film is 15 or more and an etching selectivity difference between the nitride film and an oxide film is 10 or more. Proceeded.

However, since it is difficult to implement the difference in the etching selectivity, it is difficult to apply to the actual process, thereby making it difficult to perform the self-aligned contact hole forming process.

Due to the above phenomenon, it is difficult to form a highly integrated semiconductor device, and there is a problem in that the characteristics and reliability of the semiconductor device are degraded due to the high integration of the semiconductor device.

Further, as the semiconductor device becomes more integrated, it is necessary to form a shallower depth of the impurity mixed layer, but there is a problem in that the productivity of the semiconductor device is reduced due to the complicated process and high technology.

Accordingly, in order to solve the above problems, the present invention forms a thick insulating film at the interface between the contact hole and the word line, and forms a particularly thick insulating film at the overlapping portion so that the word line is not damaged during the contact etching process. It is an object of the present invention to provide a method for forming a contact hole in a semiconductor device which improves the productivity of the semiconductor device by forming contact holes, improves the characteristics and reliability of the semiconductor device, and thereby enables high integration of the semiconductor device.

In order to achieve the above object, a method of forming a contact hole in a semiconductor device according to the present invention includes the steps of depositing a stacked structure of a conductive layer / silicide film / interlayer insulating film for word lines on a semiconductor substrate with a predetermined thickness, respectively, The interlayer insulating layer, the silicide layer and the word line conductive layer are sequentially etched using a contact mask to form an interlayer insulating layer pattern, the silicide layer pattern and the word line conductive layer pattern, wherein the silicide layer forms an undercut under the interlayer insulating layer. Forming an insulating film spacer on the sidewalls of the interlayer insulating film pattern, the silicide film pattern, and the word line conductive layer pattern; forming a lower insulating layer to planarize the entire upper surface of the semiconductor substrate; When the semiconductor substrate is exposed by self-aligned contact etching using a mask Is to include a step of forming a contact hole.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1F are cross-sectional views illustrating a method for forming a contact hole in a semiconductor device according to the present invention.

First, a word line conductive layer 11 is formed on the semiconductor substrate 40.

A tungsten silicide film 13 is formed on the word line conductive layer 11 at a predetermined thickness.

In this case, the word line conductive layer 11 is formed of a material having properties similar to those of polycrystalline silicon or polyside.

The tungsten silicide film 13 is formed to a thickness of about 500 to 2000 kPa.

Then, an interlayer insulating film 15 is formed on the tungsten silicide film 13 to a thickness of about 100 to 1000 Å.

At this time, the interlayer insulating film 15 is formed of a nitride film.

Next, the interlayer insulating layer 15 is etched by an etching process using a word line masker (not shown) to form the interlayer insulating layer 15 pattern. (Figure 1a)

The tungsten silicide layer 13 is isotropically etched by a dry method to form an under cut 17 under the interlayer dielectric layer 15 pattern and to form a tungsten silicide layer 13 pattern.

At this time, the isotropic etching process is performed by adding oxygen gas or nitrogen gas to the chlorine or fluorine-based plasma.

In addition, the isotropic etching process may be performed by a wet method.

Subsequently, the remaining portion of the tungsten silicide film 13 and the word line conductive layer 11 are subsequently anisotropically etched to form a word line conductive layer 11 pattern (FIG. 1B).

Then, a nitride film 19 is formed on the entire surface with a thickness of about 100 to 1000 mm 3. (Figure 1c)

Next, the nitride film 19 is anisotropically etched to form a nitride film spacer 19 on the sidewalls of the interlayer insulating film 15 pattern, the tungsten silicide film 13 pattern, and the word line conductive layer 11 pattern. (Figure 1d)

Then, the lower insulating layer 21 is formed to planarize the entire upper surface.

In this case, the lower insulating layer 35 is formed of an insulating material having excellent fluidity, such as B.P.S. paper (hereinafter referred to as BPSG).

The photoresist pattern 23 is formed on the lower insulating layer 35 by an exposure and development process using a contact mask (not shown).

In this case, the contact mask is misaligned compared to the contact mask used in FIG. 1A. (Figure 1e)

Subsequently, the lower insulating layer 21 is etched using the photoresist pattern 23 as a mask, and the difference in etching selectivity between the nitride layer 19 spacer and the interlayer insulating layer 15 pattern and the lower insulating layer is determined. Etching to form a contact hole 25 exposing the semiconductor substrate 40.

In this case, the contact etching process is etched by overlapping the interlayer insulating layer 15 pattern, and the spacers of the nitride layer 19 formed on the sidewalls of the non-overlapping word lines remain more than the spacers of the overlapped portions. (Figure 1f)

As described above, in the method for forming a contact hole in a semiconductor device according to the present invention, an undercut is formed by isotropically etching the silicide layer in a word line formed of a laminated structure of a conductive layer / silicide layer / interlayer insulating layer for word lines, and then By performing the ordered contact process, the overlap margin is improved during the contact process, thereby improving the yield and productivity of the semiconductor device, improving the characteristics and reliability of the semiconductor device, and thus improving the integration of the semiconductor device.

Claims (10)

Depositing a stacked structure of a word line conductive layer / silicide film / interlayer insulating film on a semiconductor substrate with a predetermined thickness, and sequentially etching the interlayer insulating film, silicide film, and word line conductive layer using a contact mask. Forming an interlayer insulating layer pattern, a silicide layer pattern, and a conductive layer pattern for a word line, wherein the silicide layer is formed under the interlayer insulating layer, and on the sidewalls of the interlayer insulating layer pattern, the silicide layer pattern, and the conductive layer pattern for a word line. Forming an insulating film spacer, forming a lower insulating layer to planarize the entire upper surface of the semiconductor substrate, and forming a contact hole exposing the semiconductor substrate by self-aligning contact etching using the contact mask. A contact hole forming method of a semiconductor device comprising the step of. The method of claim 1, wherein the word line conductive layer is formed of a material having properties similar to those of a polysilicon film or a polyside. The method of claim 1, wherein the silicide layer is formed of a tungsten silicide layer. The method of claim 1 or 3, wherein the silicide film is formed to a thickness of about 500 to 2000 GPa. The method of claim 1, wherein the interlayer insulating film is formed of a nitride film. The method of manufacturing a semiconductor device according to claim 1 or 5, wherein the interlayer insulating film is formed to a thickness of about 100 to about 1000 GPa. The method of claim 1, wherein the silicide layer etching process comprises performing an isotropic etching process and an anisotropic etching process. The method of claim 1, wherein the undercut is formed by an isotropic etching process of a wet method or an isotropic etching process of a dry method. 9. The method of claim 8, wherein the isotropic etching process of the dry method is performed by adding oxygen gas or nitrogen gas to a chlorine or fluorine plasma. The method of claim 1, wherein the self-aligned contact process is performed using the misaligned contact mask.