KR19980045335A - Manufacturing method of semiconductor device - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a cleaning method for removing particles and P ₂ O ₅ film formed on the gate polysilicon. Washing method of the present invention washing the polysilicon film with a sulfuric acid mixed solution and rinsing with ultrapure water, washing the polysilicon film cleaned with a sulfuric acid mixed solution with a hydrofluoric acid mixed solution and rinsing with ultrapure water, and washing with a hydrofluoric acid mixed solution And a step of washing the polysilicon film with ammonia mixed solution and rinsing with ultrapure water.

Description

Method of manufacturing a semiconductor device.

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a cleaning method for removing a P ₂ O ₅ film formed on a gate polysilicon film.

In general, a gate electrode pattern of a semiconductor device is formed by sequentially forming a gate oxide film and a polysilicon film on a semiconductor substrate, and performing a mask and an etching process with POCl ₃ doped to impart conductivity to the polysilicon film. . In the above process, however, the particles and the P ₂ O ₅ film are formed on the polysilicon film, thereby causing the defect of the device in the subsequent process, and the degree of integration of the semiconductor device if the particles and the P ₂ O ₅ film are not completely removed. As the increases, the lower the reliability.

Therefore, the particles and P ₂ O ₅ film as described above must be removed, the conventional particles and P ₂ O ₅ film is removed in the following manner.

In order to remove the particle P ₂ O ₅ film on the polysilicon film, first, the polysilicon film is washed with a sulfuric acid mixed solution of H ₂ SO ₄ + H ₂ O ₂ , and the cleaned polysilicon film is subjected to QDR (Quick Dump Rinse) using ultrapure water. Rinse in a manner. Then, the polysilicon film washed with the sulfuric acid mixed solution is washed with a hydrofluoric acid mixed solution of HF + H ₂ O, and the ultrapure water is overflowed. Finally, the polysilicon film washed with the hydrofluoric acid mixed solution is washed with a hydrochloric acid mixed solution of HCl + H ₂ O ₂ + H ₂ O and rinsed with ultrapure water.

However, the prior art as described above has a problem in that the HCl mixed solution used in the last step of the cleaning generates fumes due to its characteristics, so that particles on the polysilicon film cannot be removed, but rather particles are generated.

Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device that can improve device reliability by improving particle removal efficiency by using NH ₄ OH, which does not generate steam instead of HCl.

1 is a photograph showing surface roughness after washing a polysilicon film with an ammonia mixed solution at 25 ° C. in which NH ₄ OH: H ₂ O ₂ : H ₂ O = ^1t : 4: 20.

FIG. 2 is a photograph showing surface roughness after washing a polysilicon film with a 45 ° C. ammonia mixed solution having NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 2: 10. FIG.

3 is a photograph showing surface roughness after washing a polysilicon film with a 45 ° C. ammonia mixed solution having NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 4: 20. FIG.

The above object is a process of washing a polysilicon film with a sulfuric acid mixed solution and rinsing with ultrapure water, a process of washing the polysilicon film cleaned with a sulfuric acid mixed solution with a hydrofluoric acid mixed solution and rinsing with ultrapure water, and a solution with a hydrofluoric acid mixed solution The polysilicon film is washed with ammonia mixed solution and rinsed with ultrapure water.

EXAMPLE

Hereinafter, preferred embodiments of the present invention will be described in more detail.

The cleaning method for removing the particles on the polysilicon film and the P ₂ O ₅ film is as follows.

First, it is washed with sulfuric acid and a mixed solution of _{H 2 SO 4 + H 2 O} 2. At this time, the temperature of the sulfuric acid mixed solution is maintained at about 115 to 125 ℃ to suppress the exothermic reaction and steam generation of sulfuric acid. Then, the polysilicon film washed with the sulfuric acid mixed solution is rinsed in a QDR method using ultrapure water. After then, washed with a hydrofluoric acid mixed solution of a polysilicon film at room temperature for HF + H ₂ O washed with sulfuric acid mixed solution, and then, HF + H ₂ O HF mixture at room temperature for a polysilicon film is washed with sulfuric acid mixed solution After washing with the solution, the ultrapure water is overflowed. Then, the polysilicon film washed with the hydrofluoric acid mixed solution is washed with ammonia mixed solution with NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 4: 20, and then overflowed with ultrapure water and rinsed. At this time, the temperature of the ammonia mixed solution is maintained at about 45 ℃.

1 to 3 are photographs showing the surface roughness of the polysilicon film after ammonia washing according to the mixing ratio of NH ₄ OH, H ₂ O ₂ , H ₂ O in the ammonia mixed solution and the temperature of the ammonia mixed solution.

1 is a photograph of the surface of a polysilicon film after washing at 25 ° C. with an ammonia mixed solution having NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 4: 20, wherein RMS (the surface roughness of the polysilicon grains) is about Root Means Square is 4.554 nm.

Fig. 2 is a photograph of the surface of the polysilicon film after washing at 45 ° C. with an ammonia mixed solution having NH ₄ OH: H ₂ O ₂ : H ₂ O = ^1t : 2: 10, and the RMS of the polysilicon grains is 4.019 nm. .

Fig. 3 is a photograph of the surface of the polysilicon film after washing the ammonia mixed solution of NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 1: 20 at 45 ° C., wherein the RMS of the polysilicon grains is 3.526 nm. .

Therefore, the smaller the RMS value of the surface roughness is, the smaller and more uniform the grain size is. Therefore, the polysilicon film is ammonia having NH ₄ OH: H ₂ O ₂ : H ₂ O = 1: 4: 20 and having a temperature of 45 ° C. It is most preferable to wash | clean with a mixed solution, and since ammonia does not generate | occur | produce steam, it can raise the particle removal efficiency.

As described above, in the method of manufacturing a semiconductor device of the present invention, the particles and the P ₂ O ₅ film generated on the polysilicon film are completely removed, thereby improving the reliability and manufacturing yield of the device.

Meanwhile, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (6)

Washing the polysilicon film with a sulfuric acid mixed solution and rinsing with ultrapure water, Washing the polysilicon film washed with a sulfuric acid mixed solution with a hydrofluoric acid mixed solution and rinsing with ultrapure water, And a step of washing the polysilicon film washed with the hydrofluoric acid mixed solution with ammonia mixed solution and rinsing with ultrapure water. The method of claim 1, wherein the temperature of the sulfuric acid mixed solution is about 115 to 125 ℃. The method of manufacturing a semiconductor device according to claim 1, wherein the temperature of the hydrofluoric acid mixed solution is room temperature. The method of claim 1, wherein the ammonia mixed solution is a mixture of NH ₄ OH, H ₂ O ₂ , and H ₂ O. The method of claim 4, wherein the mixing ratio of NH ₄ OH: H ₂ O ₂ : H ₂ O is 1: 4: 20. The method of claim 1, wherein the temperature of the ammonia mixed solution is about 45 ° C.