Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2001-03-29
2003-01-07
Webb, Gregory E. (Department: 1751)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C438S689000, C438S745000, C134S001100, C134S001200, C134S001300, C134S002000, C510S175000
Reexamination Certificate
active
06503837
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of drying a semiconductor wafer, and more specifically, to a method of drying the semiconductor wafer so as to rinse residual etching reactants/product from the surface of the semiconductor wafer.
2. Description of the Prior Art
In semiconductor processing, lithography and etching are two commonly used processes. During lithography, light is projected from above through a photo mask onto a photoresist layer coated on a semiconductor wafer. The photoresist layer on the wafer is then exposed and developed thus creating a pattern corresponding to that of the photo mask. During etching, materials such as silicon or SiO
2
in areas on the semiconductor wafer not covered by the photoresist layer are etched followed by removal of remaining photoresist. Therefore, developing effective and accurate methods to transfer the pattern of the photo mask onto the semiconductor wafer through use of lithography and etching continues to be a top priority.
Please refer to
FIG. 1
of a schematic view of rinsing residual etching reactants/product on the surface of a semiconductor wafer
10
according to the prior art. As shown in
FIG. 1
, a semiconductor wafer
10
is positioned on an etching machine
12
comprising a cleaning solution sprayer
14
above a center of the semiconductor wafer
10
.
The semiconductor wafer
10
is spun at the beginning of the rinsing method according to the prior art. Simultaneously, a cleaning solution
16
, primarily composed of deionized water (DI water), is sprayed on the center of the surface of the semiconductor wafer
10
via the cleaning solution sprayer
14
. Therefore, the residual etching reactants/product on the surface of the semiconductor wafer
10
is rinsed. Finally, the semiconductor wafer
10
is spun dry with a nitrogen purge on the surface of the semiconductor wafer
10
(not shown), at the end of the rinsing method according to the prior art.
However, the method of rinsing residual etching reactants/product on the surface of the semiconductor wafer
10
according to the prior art is to spray the cleaning solution
16
on the center of the semiconductor wafer
10
merely via the cleaning solution sprayer
14
. By performing a spinning-dry process with a nitrogen purge on the center of the semiconductor wafer
10
, the residual etching reactants/product on the surface of the semiconductor wafer
10
is rinsed by portions of the cleaning solution
16
sprayed on the center of the semiconductor wafer
10
. Both portions of the cleaning solution
16
and most of the residual etching reactants/product are then removed from the semiconductor wafer
10
by centrifugal force caused by the spinning-dry process. Therefore, light amount of the etching solution normally resides and over-etches the edge of the semiconductor
10
so as to cause defects that affect the quality of the semiconductor wafer
10
. This then can lead to reduced yield rates in subsequent processes and reduce the quality of the product.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a method of cleaning the surface of a semiconductor wafer so as to rinse residual etching reactants/product from the surface of the semiconductor wafer.
In the preferred embodiment of the present invention, a semiconductor wafer is positioned on an etching machine comprising a cleaning solution sprayer. The cleaning solution sprayer comprises at least a first nozzle positioned above a center of the wafer center, and a second nozzle positioned above an edge of the wafer. At the beginning of the method provided in the present invention, the semiconductor wafer is spun. Simultaneously a cleaning solution is sprayed on the center and the edge of the wafer via the first nozzle and the second nozzle, respectively, to evenly rinse the residual etching reactants/product from the surface of the semiconductor wafer. Finally, a spin-drying process is performed on the semiconductor wafer with a nitrogen purge on the wafer surface at the end of the method. The preferred period of the nitrogen purge ranges from 30 to 50 seconds.
It is an advantage of the present invention against the prior art that the cleaning solution sprayer comprises a first nozzle and a second nozzle, so that the cleaning solution is sprayed on the center and the edge of the semiconductor wafer via the first nozzle and the second nozzle, respectively. This means that the residual etching reactants/product on the surface of the semiconductor wafer is evenly and thoroughly rinsed so that an over-etch on the edge of the semiconductor wafer caused by residual etching reactants/product is prevented. As a result, the quality of the semiconductor wafer and the yield rates of subsequent processes are significantly improved.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the multiple figures and drawings.
REFERENCES:
patent: 5666985 (1997-09-01), Smith, Jr. et al.
patent: 6145519 (2000-11-01), Konishi et al.
patent: 6146468 (2000-11-01), Dryer et al.
Hsu Winston
Macronix International Co. Ltd.
Webb Gregory E.
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