KR19980017521A - Etching method of semiconductor device manufacturing process - Google Patents

Abstract

It relates to an etching method of a semiconductor device manufacturing process.

In the etching method of the semiconductor device manufacturing process according to the present invention, after depositing a lower film of a certain film quality on the stepped wafer surface, and using a constant etching method on it, after laminating an upper film made of a film quality similar to the lower film and the etching rate, In the etching method of the semiconductor device manufacturing process having the process of etching the portions having different thicknesses of the upper layer at the same time, the etching rate is smaller than that of the upper layer when the etching method is used after the lower layer is laminated and before the upper layer is laminated. The method may further include stacking a separate buffer layer.

Accordingly, there is an advantage in that portions of the upper layer having different thicknesses can be simultaneously etched without etching residues without damaging the lower layer.

Description

Etching method of semiconductor device manufacturing process.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method of a semiconductor device manufacturing process, and more particularly, to an etching method of a semiconductor device manufacturing process that leaves no etching residues due to a step in anisotropic etching.

In order to manufacture a semiconductor device, a process of laminating various types of films and forming patterns on a semiconductor substrate is repeated. In this process, if a certain pattern is formed in the previous step and other films are stacked on the film, the thickness of the film deposited in the stepped portion becomes much thicker than the other parts due to the step difference in the wafer surface due to the pattern. .

This is because the particles constituting the film to be laminated are not vertically stacked upward and stacked on the stepped wafer surface, but are stacked on all exposed wafer surfaces in all accessible directions.

1 is a cross-sectional view of a portion of a process wafer at one stage of a conventional semiconductor device manufacturing process. A pattern made of the first film 11 protrudes from the flat surface of the semiconductor substrate 10, and a second film 12 and a third film 13 are stacked on the entire surface of the wafer. The photoresist 14 pattern is formed thereon. The third film is applied much thicker than the other part indicated by the thickness 'a' around the stepped pattern portion.

FIG. 2 is a diagram illustrating a case where anisotropic etching of the third layer is performed in the state of FIG. 1. Since the portion indicated by the thickness' b 'of the conduction is stacked thicker than other portions, particularly in the case of anisotropic etching, the etching residue 13' of the third layer 13 is left around the protrusion when the etching amount is not sufficient. On the contrary, when the etching amount is sufficient to prevent the etching residue 13 'from remaining, the second layer 12 may be eroded, which may cause problems in subsequent processes or malfunction of the finished semiconductor device.

In order to avoid this problem, the etching selectivity of the second and third films should be large. However, since each film is selected to suit the functional or manufacturing process needs of the semiconductor device, it cannot generally be said that the etching selectivity is good.

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching method of a semiconductor device manufacturing process that does not damage the lower layer and leaves no etch residues at the same time even when the partial thickness of the stacked films is different due to the wafer step difference.

1 is a cross-sectional view of a portion of a process wafer at one stage of a conventional semiconductor device manufacturing process.

FIG. 2 is a diagram illustrating a case where anisotropic etching of the third layer is performed in the state of FIG. 1.

3 is a view showing a part of the cross section of the wafer in the state where the buffer film is interposed according to the etching method of the present invention.

4 is a view showing a part of the cross section of the wafer after the etching method of the present invention is performed.

* Description of the symbols for the main parts of the drawings *

10: semiconductor substrate 11: first film

12: Act 2 13: Act 3

13 ': etching residue 14: photoresist

25: Buffer

According to the etching method of the semiconductor device manufacturing process according to the present invention for achieving the above object, when the lower layer of a certain film quality is laminated on the stepped wafer surface, and using a constant etching method on the lower film, the etching rate is similar to the lower film In the etching method of the semiconductor device manufacturing process having a process of etching the portions having different thicknesses of the upper film at the same time after the stacking of the upper film of the upper layer, when using the etching method after laminating the lower film and before the upper film Comprising the step of stacking a separate buffer layer having a small etching rate compared to the film is characterized in that it is further provided.

The buffer film of the present invention is preferably laminated so as to have a thin thickness as long as the lower film is not damaged according to the etching rate, and the buffer film remaining after etching the upper film does not need to be removed unless there is a problem in the function of the semiconductor device. do.

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

3 is a view showing a part of the cross section of the wafer in the state where the buffer film is interposed according to the etching method of the present invention. The second film 12 made of, for example, silicon is laminated on the stepped wafer surface by the first film 11 forming a pattern as in the prior art, and the third film 13 made of polysilicon is again placed thereon. ), A silicon oxide film is formed of the buffer film 25 before lamination.

4 is a view showing a part of the cross section of the wafer after the etching method of the present invention is performed. In this case, even if the third layer 13 made of polysilicon is etched with sufficient etching time according to the photoresist pattern without etching residue, the silicon oxide buffer layer 25 may not be etched because the etching selectivity is low. The second film 12 of material remains intact.

Therefore, according to the present invention, there is an advantage in that portions of the upper layer having different thicknesses can be simultaneously etched without etching residues without damaging the lower layer.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (1)

After stacking a lower film of a specific film quality on the stepped wafer surface, and stacking an upper film made of a film material having an etch rate similar to that of the lower film when using a constant etching method, the parts having different thicknesses of the upper film are formed. In the etching method of the semiconductor device manufacturing process having a process of etching at the same time, After the lamination of the lower layer and before the lamination of the upper layer, in the case of using the etching method, further comprising the step of laminating a separate buffer layer having a smaller etching rate compared to the upper layer. Etching method of device manufacturing process.