U.S. patent application number 09/769870 was filed with the patent office on 2001-11-22 for cassette carrier for wafer cleaning processes.
This patent application is currently assigned to Mosel Vitelic Inc.. Invention is credited to Chiu, John, Lin, Koni.
Application Number | 20010042726 09/769870 |
Document ID | / |
Family ID | 21659781 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042726 |
Kind Code |
A1 |
Chiu, John ; et al. |
November 22, 2001 |
Cassette carrier for wafer cleaning processes
Abstract
An improvement of a cassette carrier is provided to improve
wafer cleaning processes. The carrier includes a support and two
opposed suspensions positioned at both sides of the support and
each provided with a fixing mechanism for suspending edges of
cassettes. According to the present invention, the structure of the
carrier for carrying the cassettes is simplified to reduce amount
of chemicals adhered to and remained on the surface of the carrier
during wafer cleaning, thereby shortening wafer cleaning time and
enhancing wafer cleaning efficiency.
Inventors: |
Chiu, John; (Hsinchu,
TW) ; Lin, Koni; (Hsinchu, TW) |
Correspondence
Address: |
Daniel R. McClure
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, L.L.P.
Suite 1750
100 Galleria Parkway, N.W.
Atlanta
GA
30339-5948
US
|
Assignee: |
Mosel Vitelic Inc.
19, Li-Hsin Road, Science-Based Industrial Park,
Hsin-Chu
TW
|
Family ID: |
21659781 |
Appl. No.: |
09/769870 |
Filed: |
January 25, 2001 |
Current U.S.
Class: |
211/41.18 ;
118/500; 206/454 |
Current CPC
Class: |
H01L 21/68707 20130101;
H01L 21/67326 20130101 |
Class at
Publication: |
211/41.18 ;
206/454; 118/500 |
International
Class: |
A47F 007/00; A47G
019/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2000 |
TW |
89109627 |
Claims
What is claimed is:
1. A carrier for carrying cassettes loaded with wafers in wafer
cleaning processes, comprising: a support; and two opposed
suspensions positioned at bottom of said support and each provided
with a fixing mechanism for suspending said cassettes.
2. A carrier according to claim 1, wherein said fixing mechanism
comprises a groove.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to apparatus for
wafer cleaning processes, and more particularly, to an improved
cassette carrier for wafer cleaning processes.
BACKGROUND OF THE INVENTION
[0002] In the manufacture of integrated circuits (ICs), wafer
cleaning technique and cleanliness considerably affect yield,
quality and reliability thereof. Currently, a wet chemical cleaning
technique is widely used for wafer cleaning in which wafers are
sequentially rinsed in a chemical tank and a water tank, as shown
in FIG. 1. In FIG. 1, a carrier 10 has a cassette 20 that is loaded
with a plurality of wafers 22 to be cleaned at each side. The
carrier 10 comprises a support 12 and a base 14 that has a
symmetric structure to be loaded with these two cassettes 20. A
cleaning tank B containing a chemical cleaning solution or
de-ionized (DI) water is provided below the carrier 10. During
wafer cleaning, the carrier 10 is moved by a robot A and rinsed in
a plurality of cleaning tanks. The carrier 10 is rinsed in the
cleaning tank B together with the cassettes 20, as shown in FIG.
2.
[0003] When wafers in the cassette 20 are moved from a chemical
tank to a water tank, whether chemical remained on the wafers is
removed is determined by detecting the resistivity in the water
tank. According to the prior art, the chemical has been adhered to
the cassettes 20 and carrier 10, which is preferably formed of a
fluoride resin material such as PFA, PVDF and PTFE, and can
withstand heat, chemicals and mechanical strengths. However,
chemicals can be readily adhered to such material so that amount of
the chemicals remained on the carrier surface is increased.
Therefore, when the wafers are cleaned in the water tank, the
cleaning time necessary for removing the chemicals adhered to the
carrier and cassettes is increased, thereby affecting the wafer
cleaning efficiency.
[0004] Consequently, it is desired to improve the wafer cleaning
process in view of the above disadvantages.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to set forth an
improved cassette carrier for wafer cleaning processes, in which
the carrier has a decreased volume to be steeped in chemical
solution so as to decrease chemicals adhered to and remained on the
carrier.
[0006] According to the present invention, a cassette carrier for
improving wafer cleaning processes comprises a support to be
supported by a robot, and two opposed suspensions positioned at
both sides of the support and provided with a fixing mechanism for
suspending edges of cassettes in horizontal orientation.
[0007] One aspect of the present invention resides in that the
carrier is improved to reduce the volume thereof, thereby
decreasing the amount of chemicals adhered to and remained on the
surface of the carrier during the wafer rinsed in a chemical tank
and reducing the cleaning time in a water tank.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] These and other objects, features and advantages of the
present invention will become apparent to those skilled in the art
upon consideration of the following description of the preferred
embodiments of the present invention taken in conjunction with the
accompanying drawings, in which:
[0009] FIG. 1 and FIG. 2 are schematic views showing a conventional
wafer cleaning process in a cleaning tank and equipment to be used;
FIG. 3 shows a preferred embodiment of the present invention;
[0010] FIG. 4 is a schematic view showing that cassettes are
carried by the apparatus shown in FIG. 3; and
[0011] FIG. 5 shows a comparison result between effects of wafer
cleaning processes for the prior art carrier and the inventive
carrier.
DETAILED DESCRIPTION
[0012] An embodiment of the present invention is shown in FIG. 3,
in which a carrier 30 comprises a support 32 and two suspensions 34
provided at bottom of the support 32. The suspensions 34 are
symmetrically positioned at both sides of the support 32. Each
suspension 34 has a fixing mechanism for fixing and suspending a
cassette. In this embodiment, the fixing mechanism comprises
grooves 342.
[0013] The carrier 30 shown in FIG. 3 with the support 32 holding
the cassettes 40 used in wafer cleaning processes is shown in FIG.
4. The cassette 40 is formed with two extended flanges 402 and an
engagement part 404 at one side corresponding to the groove 342.
The cassette 40 is suspended from the suspension 34 by sliding the
engagement part 404 into the groove 342 and pushing the flanges 402
against the top of the suspension 34. The suspension 34 can be
integrally formed with the support 32 or be coupled with the
support 32 in a known manner, and it can support the cassette 40
loaded with wafers 22 and substantially maintain balance of the
cassette 40.
[0014] The carrier 30 is a simplified structure which provides a
robot A for fixing and supporting the cassettes 40. In this
embodiment, grooves 342 are used for receiving the cassettes 40. In
other embodiments, a suspension for fixing a cassette can be varied
on the basis of structure of the cassette.
[0015] Apparently, compared with the prior art carrier 10, the
carrier 30 according to the present invention is simplified in
structure and has a reduced volume. It is advantageous in that when
the carrier 30 together with the cassettes 40 and wafers 22 is
cleaned in a chemical tank, amount of chemical adhered to and
remained on the carrier 30 is minimized, such that time for the
subsequent cleaning in a water tank can be shortened. Since the
cleaning process in the chemical tank or water tank is to remove
contaminant or residual chemical on the wafer, adhesion of the
chemical to the carrier is undesirable. Therefore, decrease of the
amount of the chemical adhered to and remained on the carrier
shortens the time for the subsequent cleaning in the water
tank.
[0016] As above-described, the difference of the wafer cleaning
efficiencies between the carrier 10 and carrier 30 can be obtained
by detecting the resistivity variation. FIG. 5 shows an experiment
result in which DATA 1 shows resistivity variation when the carrier
30 is impregnated in the water tank, while DATA 2 shows resistivity
variation when the prior art carrier 10 is under the same condition
with water flowing at a rate of 40 LPM (Liter Per minute) and in a
resistance of 8-10 M.OMEGA. before the wafer is rinsed. As known
from the drawing, during wafer cleaning, when the prior art carrier
10 is impregnated in the water tank, the resistivity remarkably
decreased and wouldn't rise. It is impossible for an operator to
determine whether the wafers in the water tank are clean if the
resistivity does not rise, since the decreased value of the
resistivity might be caused by the residual chemical on the carrier
10. In the past, the cleaning operation in the water tank is
finished on the basis of operator's experience and the cleaning
time, and thus wafer cleaning is doubtable. If a wafer is not
clean, the residual chemical will adversely affect the equipment
for the subsequent spin dry process. For example, particles or rust
might be caused, which would influence cleanliness of wafers.
According to the carrier 30 of the present invention, the
resistivity is slightly reduced and readily increased, so that the
cleaning time is shortened and an operator can easily determine if
the cleaning operation is completed.
[0017] In summary, the carrier of the present invention is
simplified in structure, and thus the residual chemical amount
during wafer cleaning is considerably decreased, thereby shortening
the wafer cleaning time and improving the wafer cleaning
efficiency.
[0018] While the present invention has been described in
conjunction with preferred embodiments thereof, it is evident that
many alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and scope thereof as set forth in the appended
claims.
* * * * *