Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
2000-10-24
2001-08-28
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C438S753000, C134S001200, C134S024000, C134S055000, C156S345420
Reexamination Certificate
active
06281137
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a chemical treatment apparatus and a chemical treatment method, and more particularly to a chemical treatment apparatus and a chemical treatment method which are applied to a cleaning treatment step and an etching step in a semiconductor device manufacturing process.
A wafer treatment using chemical has been hitherto performed in each process of a semiconductor device manufacturing field. For example, in a semiconductor wafer manufacturing process, such a wafer treatment is performed in a cleaning step for removing unneeded materials (contaminants) adhering to the surfaces of wafers, in a wet etching step of a process for forming semiconductor devices on wafers, etc. As the microstructure of semiconductor devices is finer, not only the cleaning effect, but also uniformity of wet etching are required to be more remarkably enhanced.
A dip treatment in which plural wafers to be treated (hereinafter referred to as “target wafers”) are dipped into chemical all together is known as a typical chemical treatment method.
FIGS. 1A
to
1
C are diagrams showing a conventional chemical treatment apparatus using the dip treatment method. A chemical treatment apparatus
30
includes a nozzle type circulating treatment tank
31
. As shown in
FIG. 1A
, chemical
40
is overflowed in the direction indicated by an arrow A from the treatment tank
31
into an outer tank
32
which is provided at the outer periphery of the treatment tank
31
, and contaminant materials in the chemical
40
are discharged into the outer tank
32
together with the chemical
40
. Thereafter, the chemical
40
in the outer tank
32
is guided through a pump
33
to a filter
34
in which the chemical
40
is filtered and cleaned, and then supplied into the treatment tank
31
again.
At this time, in order to effectively bring the chemical
40
into contact with the surface of a target wafer
50
dipped in the chemical
40
in the treatment tank
31
, the chemical
40
is fed from the filter
34
to jet pipes
35
serving as nozzles which are provided at the bottom side in the treatment tank
31
, and supplied into the treatment tank
31
through small jetting holes
36
formed on the jet pipes
35
.
In the dip treatment, plural target wafers
50
are normally dipped in the chemical
40
while being arranged substantially in parallel and at predetermined intervals. Therefore, a pair of jet pipes
35
are disposed in the chemical treatment tank
30
so as to confront each other. The plural target wafers
50
are dipped between the jet pipes
35
and above the jet pipes
35
so that the arrangement direction of the target wafers
50
is substantially parallel to the length direction of the jet pipes
35
. The jet holes
36
are formed in each jet pipe
35
so that the chemical
40
is jetted to the gaps between neighboring target wafers
50
and to the substantial centers of the target wafers
50
(in the directions indicated by arrows B of FIGS.
1
A and
1
B). These plural jet holes
36
are formed in each jet pipe
35
along the length direction of the jet pipe
35
.
However, in the chemical treatment using the chemical treatment apparatus
30
shown in
FIG. 1
, all of the chemical
40
jetted from the jet pipes
35
does not necessarily flow upwardly and overflow from the treatment tank
31
into the outer tank
32
, but a part of the chemical
40
convectively returns from the upper side of the target wafer
50
toward the jet pipes
35
as indicated by an arrow G in FIG.
1
A. The chemical
40
which returns to the portions surrounding the jet pipes
35
contains various contaminant materials removed from the target wafer
50
, and stagnates in the neighborhood of the bottom portion
31
a
of the treatment tank
31
as indicated by an arrow H in
FIG. 1C
, so that a dirty stagnant layer
41
is formed in the neighborhood of the bottom portion
31
a.
The chemical
40
stagnates in the neighborhood of the bottom portion
31
a
of the treatment tank
31
as described above because there is not provided any means of inducing flow of the chemical
40
in the neighborhood of the jet pipes
35
, particularly in the neighborhood of the bottom portion
31
a
of the treatment layer
31
which is at the lower side of the jet pipes
35
.
When the stagnant layer
41
as described above is formed, the circulating efficiency of the chemical
40
in the treatment tank
31
is lowered. As a result, for example when the chemical treatment is a water washing treatment after the wet etching step, a large amount of wet etching agent to be removed remains ununiformly on the surface of the target wafer
50
, and thus the uniformity of the etching in the plane of the target wafer
50
is deteriorated. Further, the lowering of the circulating efficiency of the chemical
40
reduces the washing effect of the target wafer
50
, and the contaminant materials taken into the chemical
40
also adhere to the surface of the target wafer
50
again. If semiconductor devices are manufactured while the target wafers
50
are left contaminated, the electrical reliability and the manufacturing yield of the semiconductor devices are reduced.
Further, in order to remove the stagnant layer
41
, the treatment tank
31
must frequently washed, and the chemical
40
being used must be more frequently exchanged. Therefore, the following various troubles occur: a large amount of labor is imposed on a maintenance work; the manufacturing cost rises; the manufacturing yield is reduced because the workability of the chemical treatment apparatus
30
is reduced, etc.
SUMMARY OF THE INVENTION
Therefore, in order to solve the above problems, a chemical treatment apparatus according to the present invention is characterized in that a jet pipe provided at the bottom portion in a treatment tank contains at least first holes for jetting chemical upwardly and second holes for jetting chemical in a direction different from that of the first holes.
According to the chemical treatment apparatus of the present invention, the jet holes of the jet pipe comprise the first holes for jetting the chemical upwardly and the second holes for jetting the chemical in the direction different from the jet direction of the first holes. Therefore, for example when a target wafer is disposed above the jet pipes in the treatment tank and the first holes are set to jet the chemical toward the substantial center of the target wafer while the second holes are set to jet the chemical toward the bottom portion of the treatment tank which is at the lower side of the target wafer, there are formed not only a chemical flow directing from the substantial center of the target wafer to the upper side, but also a chemical flow directing to the bottom portion in the treatment tank. Accordingly, even when the chemical convectively returns from the upper side of the target wafer to the vicinity of the jet pipes, the chemical is prevented from stagnating at the bottom side of the treatment tank by the chemical flow directing to the bottom side of the treatment tank, and thus no stagnant layer occurs at the bottom side. Therefore, the chemical efficiently flows in the treatment tank. Further, since no stagnant layer is formed, it is unnecessary to frequently perform a cleaning work of the treatment tank and an exchange work of the chemical.
According to the chemical treatment apparatus of the present invention, the etching uniformity when the wet etching is performed can be remarkably enhanced, and also the overall surface of the target wafer can be uniformly and sufficiently cleaned when the cleaning treatment is performed, so that the stable chemical treatment can be performed. Further, the contaminant materials in the chemical can be greatly suppressed from adhering to the surface of the target wafer again. In addition, since no stagnant layer is formed, the labor needed to clean the treatment tank and exchange the chemical can be greatly reduced. Further, the lifetime of the chemical being used is expected to be lengthened, and the cost
Iwamoto Hayato
Kurosawa Kiyoshi
Kananen Ronald P.
Rader Fishman & Grauer
Sony Corporation
Umez-Eronini Lynette T.
Utech Benjamin L.
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