Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2001-06-13
2003-07-08
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S135000, C134S002000, C134S018000, C134S021000, C134S902000, C034S340000, C034S471000
Reexamination Certificate
active
06589360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the washing of semiconductor wafers during the manufacturing of semiconductor devices. More particularly, the present invention relates to a method of and apparatus for drying wafers at the end of a wet-wash process carried out in the course of semiconductor fabrication.
2. Description of the Related Art
During the fabricating of semiconductor devices from silicon wafers, the wafers are exposed to and contaminated by various particles or chemicals. As the integrated circuits of semiconductor devices become smaller and more highly integrated, contaminants as small as about 0.1 &mgr;m in diameter can now affect the operability of the semiconductor devices. Therefore, it is very difficult to keep the wafers sufficiently clean.
Today, the cleaning of the wafers accounts for approximately 30~40% of the total manufacturing process. The cleaning process thus continues to grow in importance as the design rule of the semiconductor devices decreases.
FIG. 1
shows a drying system
50
of a conventional wet station for cleaning wafers. As shown in
FIG. 1
, the drying system
50
comprises a loader
32
, a process bath
14
, a lid
40
, an unloader
34
, and an unloading stage
18
. The arrows (solid lines) designated by reference numeral
36
represent the path along which elements holding the wafer are moved through the system
50
. On the other hand, the arrows (dotted lines) designated by reference numeral
38
represent the path along which the elements are moved through the system
50
after leaving the wafer off at some point in the station.
More specifically, the loader
32
transfers a wafer
31
from a wash bath
12
to the process bath
14
. The washing of the wafer in the wash bath
12
constitutes the final phase of a wet-wash process.
The process bath
14
serves to rinse the wafer
31
. To this end, the process bath comprises a tub of deionized water
15
. The process bath
14
also comprises a lift or elevator
13
for moving the wafer
31
into/out of the tub, and an outlet valve
19
for discharging the deionized water
15
from the tub.
The lid
40
is positioned above the process bath
14
. The lid
40
comprises a gas distributer (not shown). A dried gas such as nitrogen or IPA (isopropyl alcohol) is blown onto the wafer
31
through the gas distributer to dry the rinsed wafer.
The unloader
34
transfers the wafer
33
from the elevator
13
to the unloading stage
18
. At this time, the wafer
33
has already finished drying on the elevator
13
. A carrier
17
for receiving the wafer
33
is positioned under the unloading stage
18
. When a predetermined number of the wafers
33
have been moved onto the unloading stage
18
, the unloading stage
18
containing the wafers
33
is lowered into the carrier
17
and the wafers
33
are thereby transferred into the carrier
17
.
FIG. 2
is a flow chart of the drying process
20
carried out by the drying system
50
. The drying process
20
will be described in detail below referring to
FIGS. 1 and 2
.
First, a wafer
31
that has already been washed in the wash bath
12
is prepared (step
21
).
Next, a wafer-loading step
22
is carried out. In order to submerge the wafer
31
in the deionized water
15
, first, the elevator
13
is raised above the level of the deionized water
15
(sub-step
22
a
). The loader
32
picks up the wafer
31
in the wash bath
12
and places the wafer
31
on the elevator
13
(sub-step
22
b
).
Then, the elevator
13
holding the wafer
31
is lowered into the deionized water
15
. Thus, the wafer
31
is rinsed by the deionized water
15
(step
23
). During this time, the loader
32
is returned to its former position.
Next, the wafer
31
is dried (step
24
). To this end, the lid
40
is moved over the process bath
14
(sub-step
24
a
). The elevator
13
supporting the wafer
31
is raised above the deionized water
15
to a position at which the wafer
31
is covered by the lid
40
(sub-step
24
b
). Nitrogen or IPA gas is injected (sub-step
24
c
) from the lid
40
onto the wafer
31
to dry the wafer
31
.
Finally, the wafer
31
is unloaded (step
25
). First, the deionized water
15
is discharged from the tub of the process bath
14
by opening the outlet valve
19
(sub-step
25
a
). The elevator
13
supporting the wafer
31
is then lowered into the empty tub of the process bath
14
(sub-step
25
b
). Next, the lid
40
is returned to its former position (sub-step
25
c
). Subsequently, the elevator
13
still supporting the wafer
31
is again lifted above the tub of the process bath
14
(sub-step
25
d
). The unloader
34
picks up the wafer
31
on the elevator
13
and transfers the wafer
31
to the unloading stage
18
(sub-step
25
e
).
The above-described conventional drying system has a drawback in that it has a complex structure that takes a long time to carry out a cycle of operation comprising the drying process. Furthermore, the wafer is exposed to the air for a long period of time during the process. Accordingly, watermarks can readily form on the wafers.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide apparatus for drying a wafer and having a short cycle of operation.
Another object of the present invention is to provide apparatus for drying a wafer while minimizing the time that the wafer is exposed to external air.
In order to achieve these objects, the present invention provides a drying system comprising a process bath that includes a tub of deionized water and an elevator for moving the wafer from a position beneath the surface of the water to a position above the tub, a loader for transferring the wafer from a wash bath to the elevator of the process bath, an unloading stage, and a lid comprising an integrated lid body, gas distributer, wafer chuck and reciprocating drive for drying the wafer after the wafer is rinsed in the process bath and for transferring the wafer to the unloading stage.
Preferably, the lid body is transparent so that the wafer can be seen therethrough.
Another object of the present invention is to provide a method of drying a wafer in a short amount of time.
To achieve this object, the present invention provides a drying method in which a wafer is prepared for being dried after the wafer has undergone the final phase of a wash process in a wash bath, an elevator is positioned beneath the surface of rinsing liquid of a process bath, the wafer is transferred from the wash bath to the process bath, and the wafer is loaded onto the elevator while the elevator is positioned beneath the surface of the rinsing liquid. Accordingly, the wafer is submerged in the rinsing liquid without the need to mount the wafer on the elevator and then lower the elevator once the loader has arrived at the process bath.
Still further, another object of the present invention is to provide a method of drying a wafer in a short cycle and while minimizing the exposure of the wafer to external air.
To achieve this object, the present invention also provides a drying method comprising the steps of preparing a wafer for being dried after the wafer has undergone the final phase of a washing process in a wash bath, transferring the wafer from the wash bath to an elevator of a process bath, and rinsing the wafer with rinsing liquid of the process bath, moving a lid to a position above the process bath, subsequently raising the elevator to move the rinsed wafer into a cavity defined in the lid, securing the wafer to the lid, injecting a dried gas into the cavity and onto the wafer to thereby dry the wafer within the cavity, and moving the lid with the wafer secured within the cavity to an unloading stage.
Finally, another object of the present invention is to ensure that the method above provides a sufficiently large drying capacity. To achieve this object, the dried gas is injected onto the wafer within the cavity of the lid while the lid is being moved to the unloading stage.
REFERENCES:
patent: 5940985 (1999-08-01), Kamikawa et
Choi Hyoung Chul
Jeon Pyeong Sik
Gulakowski Randy
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
Winter Gentle E
LandOfFree
Drying system for drying semiconductor wafers and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Drying system for drying semiconductor wafers and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drying system for drying semiconductor wafers and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3008750