U.S. patent application number 13/052173 was filed with the patent office on 2011-07-14 for semiconductor wafer cleaning system and method.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Tae-Joon Kim, Young-Choul Kook, Ki-Hwan Park.
Application Number | 20110168211 13/052173 |
Document ID | / |
Family ID | 32226282 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110168211 |
Kind Code |
A1 |
Park; Ki-Hwan ; et
al. |
July 14, 2011 |
SEMICONDUCTOR WAFER CLEANING SYSTEM AND METHOD
Abstract
A method of and system for cleaning semiconductor wafers
minimizes the exposure of the wafers to the air by washing, rinsing
and drying the wafers in one cleaning chamber. The system includes
a wafer support by which a plurality of wafers can be supported in
the cleaning chamber as oriented vertically and spaced from each
other, and tubular de-ionized water supply nozzles extending
longitudinally in the direction in which the wafers are spaced from
each other as disposed to the sides of the wafers. Each de-ionized
water supply nozzle has an inner nozzle passageway, and a plurality
of sets of nozzle holes extending radially through the main body of
the nozzle from the inner nozzle passageway. Each such set of
nozzle holes subtends an angle of 80.about.100.degree. in a
vertical plane and is directed towards a surface of a respective
wafer W. During a primary rinse procedure, the de-ionized water is
supplied to the de-ionized water spray nozzles, and the liquid in
the cleaning chamber is simultaneously discharged from a lower part
of the chamber and by being allowed to overflow the chamber. The
supplying of the de-ionized water to the de-ionized water spray
nozzles and the discharging of the cleaning chamber are carried out
in proportions that minimize differences in the etching rate of a
wafer across the surface thereof.
Inventors: |
Park; Ki-Hwan; (Suwon-city,
KR) ; Kim; Tae-Joon; (Suwon-city, KR) ; Kook;
Young-Choul; (Suwon-city, KR) |
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
32226282 |
Appl. No.: |
13/052173 |
Filed: |
March 21, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10695770 |
Oct 30, 2003 |
7931035 |
|
|
13052173 |
|
|
|
|
Current U.S.
Class: |
134/26 |
Current CPC
Class: |
B08B 3/048 20130101;
H01L 21/67028 20130101; B08B 3/02 20130101; B08B 3/102 20130101;
H01L 21/67051 20130101; Y10S 134/902 20130101 |
Class at
Publication: |
134/26 |
International
Class: |
B08B 3/00 20060101
B08B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2002 |
KR |
2002-69630 |
Claims
1. A method of cleaning semiconductor wafers, comprising: filling a
cleaning chamber with a cleaning solution; washing a plurality of
wafers by submerging the wafers in the cleaning solution within the
cleaning chamber with the wafers being oriented vertically and
spaced from each other in a first direction; subsequently rinsing
the vertically oriented wafers within the cleaning chamber by
supplying de-ionized water to de-ionized water spray nozzles having
nozzle holes directed towards respective vertically oriented
surfaces of the wafer, and thereby spraying the de-ionized water
into the cleaning chamber and onto the surfaces of the wafers
within the chamber; continuing the spraying of the de-ionized water
into the cleaning chamber such that liquid in the cleaning chamber
begins to overflow the cleaning chamber; draining the liquid in the
cleaning chamber from a lower part of the cleaning chamber as the
de-ionized water is sprayed into the cleaning chamber, and the
liquid overflows the cleaning chamber; and controlling the
supplying of the de-ionized water to the de-ionized water spray
nozzles and said draining of said liquid such that liquid in an
amount of 92-97 weight % of the de-ionized water that is being
supplied by the nozzles into the cleaning chamber is simultaneously
discharged from the cleaning chamber through the lower part of the
cleaning chamber 30, while liquid in an amount of 3-8 weight % of
the de-ionized water that is being supplied by the nozzles is
simultaneously discharged as overflowing the cleaning chamber, all
while the wafers remain within the cleaning chamber.
2. The method of claim 1, wherein said controlling the supplying of
the de-ionized water to the de-ionized water spray nozzles
comprises regulating the flow of de-ionized water through said
nozzles to a rate of 21.about.26 l/min.
3. The method as claimed in claim 1, wherein said spraying of the
de-ionized water into the cleaning chamber comprises spraying the
water onto the surfaces of the over a range of 80.about.100.degree.
in a vertical plane in which each of said surfaces lies.
4. The method as claimed in claim 2, wherein said spraying of the
de-ionized water into the cleaning chamber comprises spraying the
water onto the surfaces of the over a range of 80.about.100.degree.
in a vertical plane in which each of said surfaces lies.
5. The method as claimed in claim 1, wherein said discharging of
the de-ionized water form the lower part of the leaning chamber is
carried out at least two locations aligned in said first direction
in which the wafers W are spaced from each other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional of application Ser. No. 10/695,770,
filed Oct. 30, 2003, which is incorporated herein by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to the cleaning of
semiconductor wafers. More particularly, the present invention
relates to a method of and apparatus for washing, rinsing and
drying semiconductor wafers all within in one cleaning chamber.
[0004] 2. Description of the Related Art
[0005] Semiconductor devices are generally manufactured by
selectively and repetitively performing respective unit processes
such as photolithography, etching, ashing, diffusion, chemical
vapor deposition, ion implantation and metal deposition processes.
These processes, when performed in series, produce at least one or
more conductive layers, semiconductor layers and insulator layers
on a wafer. Furthermore, each unit process is typically followed by
a respective cleaning process for removing impurities from the
wafer, e.g., a layer of undesirable material, byproducts of the
reaction created during the unit process, or various kinds of
foreign substances.
[0006] A prior art semiconductor wafer cleaning system for removing
various impurities from a wafer will now be described with
reference to FIGS. 1 and 2. A given number of wafers W are mounted
in a cassette C after a unit process has been performed on the
wafers W. The cassette of wafers W is then transferred by a loading
unit 10 to an aligning unit 12 of the cleaning system (ST102).
Next, the wafers W are aligned by the aligning unit 12 (ST104) so
as to all be oriented in the same direction. The wafers W are next
transferred by a transfer device 14 (ST106) to a first transfer
unit 16. The first transfer unit 16 checks the number of wafers W
in the cassette C (ST108), removes the wafers W from the cassette
(ST110), and transfers the wafers W to a robot 18 (ST112).
[0007] The wafers W are conveyed by the robot 18 sequentially
through a plurality of washing tubs 22 (ST114). At least one first
washing tub 22 contains a cleaning solution of an acid or alkaline
diluted with de-ionized water for cleaning the wafers W, whereas at
least one second washing tub 22 disposed immediately downstream of
the first washing tub(s) 22 contains de-ionized water to rinse away
any of the chemicals (acid or alkaline) remaining on the surface of
the wafers W. The cleaning process that is carried out in each
respective washing tub 22 is facilitated by causing the cleaning
solution and/or the de-ionized water to overflow the tub 22. Also,
the final step of the rinsing procedure is a non-resistance
measurement of the impurities.
[0008] A drying unit 24 is disposed adjacent to the washing tubs 22
to remove the de-ionized water from the wafer W (ST116). The drying
process is performed in an atmosphere of vapors of Isopropyl
Alcohol (IPA) to remove moisture from the surface of the wafers
W.
[0009] The dried wafers W are then transferred to a second transfer
unit 26 by the robot 18 (ST118). The second transfer unit 26 aligns
the wafers W (ST120) and simultaneously checks whether the same
number of wafers W counted by the first transfer unit 16 have been
received, i.e., whether all of the wafers have been cleaned
(ST122). Furthermore, the second transfer unit 26 mounts the wafers
W into a cassette C positioned at a stand-by unit 20 (ST124). Once
all of the cleaned and dried wafers W are mounted in the cassette
C, the cassette C is unloaded from the cleaning system (ST126).
[0010] As is clear from the description above, the components of
the prior art cleaning system are disposed in line so that the
various steps of the overall cleaning procedure can be carried out
in succession. More specifically, the wafers W are transferred from
a washing tub(s) 22 containing chemicals to a washing tub 22
containing only de-ionized water (for a primary rinse), and then
again to another washing tub 22 containing de-ionized water (for a
secondary rinse). The rinsed wafers W are then moved from the last
washing tub 22 to the drying unit 24.
[0011] The wafers W are thus exposed to the air for a considerable
period time while the wafers W are being moved to the drying unit
24. The exposure of the wafers W allows oxygen O.sub.2 in the air
to dissolve into moisture on the wafer surface. Spots of SiOx are
then formed on the wafer surface because the oxygen O.sub.2 reacts
with the poly Si of the wafer and then dries naturally. These spots
remain as they are as inorganic matter of the silica group or
adsorb various other foreign substances in the air. These so-called
water spots can produce contact defects.
[0012] Furthermore, the various chemicals or de-ionized water in
which the wafers W are submerged are kept flowing from a lower part
to an upper part of the washing tub 22 (overflow cleaning method).
Thus, a difference in the etching rate of the wafers occurs, as
between the lower and upper portions of the wafers 22 in the tubs
22.
[0013] FIG. 3 illustrates a conventional wafer cleaning apparatus
aimed at obviating the problems described above in connection with
the system of FIG. 1. In this apparatus, a plurality of wafers W
are separated from the cassette C and stand by, a cleaning chamber
30 is filled with a cleaning solution comprising chemicals diluted
the de-ionized water, and the wafers W are submerged in the
cleaning solution. After a given time elapses, i.e., once enough
time has been given for the cleaning solution to clean the wafers
W, the cleaning solution is discharged from the cleaning chamber 30
while de-ionized water is supplied into the chamber 30. Thus, the
wafers W are rinsed in the same chamber 30. Next, the de-ionized
water is drained from the chamber 30 while the chamber 30 is filled
with IPA vapor, thereby drying the wafers. Subsequently, heated
N.sub.2 gas is introduced into the cleaning chamber 30 while the
IPA vapors are discharged.
[0014] Such a cleaning system washes, rinses and dries the wafers W
all within in one chamber 30 to minimize the exposure of the wafers
W to the air during the overall cleaning process. However, this
process requires much more time than the process of FIG. 2 based on
an in-line disposition of washing tubs 22.
SUMMARY OF THE INVENTION
[0015] An object of the present invention is to provide a
semiconductor wafer cleaning system and method in which washing,
rinsing and drying operations are carried out in one cleaning
chamber and yet, very few water spots or other particle defects are
caused.
[0016] Another object of the present invention is to provide a
semiconductor wafer cleaning system and method in which washing,
rinsing and drying operations are carried out in one cleaning
chamber, and yet the etching rate is uniform across the surface of
the wafer.
[0017] According to one aspect of the present invention, a
semiconductor wafer cleaning system comprises a cleaning chamber
that can accommodate a plurality of wafers as spaced from one
another in a first direction, a cleaning solution by which the
cleaning chamber can be filled with cleaning solution, a discharge
section by which liquid in the cleaning chamber can be discharged,
and de-ionized water supply nozzles for spraying deionized water
into the cleaning chamber towards the wafers, wherein each of the
de-ionized water supply nozzles has a main body in the form of a
pipe defining an inner nozzle passageway, and a plurality of sets
of nozzle holes connected to the inner nozzle passageway, each set
of said nozzle holes subtending an angle of 80.about.100.degree.
about the inner nozzle passageway from which the set of nozzle
holes extends so that the de-ionized water is sprayed through each
set of nozzle holes over a range of 80.about.100.degree. as
measured in the circumferential direction of the main body of the
nozzle.
[0018] The discharge section includes at least one discharge pipe
connected to a lower part of said cleaning chamber, and an overflow
tank surrounding an upper part of said cleaning chamber. Also, a
control means controls the rate at which the de-ionized water is
sprayed in to the cleaning chamber, and the rates at which the
liquid is discharged from the the cleaning chamber via the
discharge pipe and overflow tank.
[0019] Preferably, each set of nozzle holes consists of five nozzle
holes disposed at equal angular intervals relative to each other,
and centered relative to the centers of vertically oriented wafers.
Furthermore, the inner nozzle passageway preferably has a diameter
(inner diameter of the pipe) of 0.8.+-.0.05 mm, whereas the nozzle
holes preferably each have a diameter of .about.0.5.+-.0.05 mm.
[0020] According to another aspect of the present invention, a
method of cleaning semiconductor wafers comprises washing a
plurality of wafers by submerging the wafers in cleaning solution
within a cleaning chamber with the wafers being oriented vertically
and spaced from each other in a first direction, subsequently
rinsing the vertically oriented wafers within the cleaning chamber
by spraying de-ionized water onto the surfaces of the wafers within
the chamber using de-ionized water spray nozzles, simultaneously
discharging liquid from the cleaning chamber by draining the liquid
from a lower part of the cleaning chamber, and allowing the liquid
to overflows the cleaning chamber, and controlling the supply of
the de-ionized water to the de-ionized water to the deionized water
spray nozzles and the discharging of the liquid such that liquid in
an amount of 92-97 weight % of the de-ionized water that is being
supplied by the nozzles into the cleaning chamber is simultaneously
discharged from the cleaning chamber through the lower part of the
cleaning chamber, while only liquid in an amount of 3-8 weight % of
the de-ionized water that is being supplied by the nozzles is
simultaneously discharged as overflowing the cleaning chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other objects, features and advantages of the
present invention will become more fully understood from the
detailed description given hereinbelow and the accompanying
drawings, wherein:
[0022] FIG. 1 is a schematic diagram of a conventional
semiconductor wafer cleaning system;
[0023] FIG. 2 is a flowchart of the wafer cleaning process
performed by the system of FIG. 1;
[0024] FIG. 3 is a schematic diagram of a conventional wafer
cleaning apparatus;
[0025] FIG. 4 is a schematic diagram of a semiconductor wafer
cleaning system according to the present invention;
[0026] FIG. 5 is a partial sectional view of a de-ionized water
supply nozzle of the semiconductor wafer cleaning apparatus
according to the present invention; and
[0027] FIG. 6 is a graph illustrating etching rate (E/R)
differences, and particles or defect on a wafer, in connection with
each of several embodiments of the semiconductor wafer cleaning
apparatus according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] A semiconductor wafer cleaning system and method according
to the present invention will be described with reference to FIGS.
4 through 6.
[0029] Referring first to FIG. 4, a semiconductor wafer cleaning
system includes a cleaning chamber 30 in which cleaning, rinse and
drying operations are performed, an overflow tank disposed around
the top of the cleaning chamber 30, a wafer support member 32
disposed at the bottom of the chamber 30 for supporting the wafers
W in the chamber 30 as oriented vertically and spaced apart from
each other, and a de-ionized water supply nozzle 34 for supplying
de-ionized water into the chamber 30. The cleaning chamber 30 has
such a capacity that 25 wafers W can be freely loaded into the
chamber 30 and taken out of the chamber by a robot, and can be
submerged in cleaning solution that fills the cleaning chamber 30.
However, the present invention is not limited to having a capacity
that accommodates 25 wafers W.
[0030] In operation, first a plurality of wafers W are removed from
a cassette and stand by adjacent the cleaning apparatus. Then a
controller (not shown) issues a command to fill the cleaning
chamber 30 with a cleaning solution via a pipe 38 connected to a
lower part of the cleaning chamber 30. The cleaning solution is
provided by diluting an alkali or acid, stored in a chemical tank
36, with de-ionized water at a predetermined amount. Once the
cleaning solution fills the cleaning chamber 30, a controller
commands a robot R to load the wafers W in the stand-by state into
the chamber 30 and onto the wafer support member 32. Thus, the
wafers W are submerged in the cleaning solution within the cleaning
chamber 30, and are left that way for a predetermined period of
time so as to be cleaned by the cleaning solution.
[0031] Next, the controller initiates a primary rinse procedure in
which the de-ionized water is supplied to each of the wafers W
through the de-ionized supply nozzle 34. Various parameters, under
which the de-ionized water is supplied to each of the wafers W and
is discharged during the rinse procedure, were determined through
experiments conducted by the present inventors, as summarized below
in Table 1.
[0032] The results provided by these embodiments are shown in the
graph of FIG. 6
TABLE-US-00001 TABLE 1 Supply rate Wastewater discharge of de-
Diameter of Diameter of Supply angle rate during de-ionized Number
of ionized inner nozzle outer nozzle of de-ionized water supply
procedure discharge water (A) (B) (C) water (D) (E) pipes (F) 1 36
l/min 1.8~2.3 .phi. 0.8 .+-. 0.05 .PHI. 90.degree. pipe 70: 1 12
holes overflow 30 2 36 l/min 1.0 .+-. 0.1.phi. 0.8 .+-. 0.05 .PHI.
90.degree. pipe 80: 2 12 holes overflow 20 3 30 l/min 0.8 .+-.
0.05.phi. 0.5 .+-. 0.05 .PHI. 90.degree. pipe 90 : 2 5 holes
overflow 10 4 19 l/min 0.8 .+-. 0.05.phi. 0.5 .+-. 0.05 .PHI.
95.degree. pipe 95: 2 6 holes overflow 05 5 24 l/min 0.8 .+-.
0.05.phi. 0.5 .+-. 0.05 .PHI. 90.degree. pipe 95: 2 5 holes
overflow 05
[0033] As shown in FIGS. 4 and 5, each de-ionized water supply
nozzle 34 comprises a pipe that extends longitudinally in the
direction in which the wafers W are arrayed (spaced), and is
connected to a de-ionized water supply line. Each nozzle 34 has a
main nozzle passageway, namely the longitudinally extending opening
of the pipe that has a diameter corresponding to the inner diameter
of the nozzle 34, and a plurality of sets of nozzle openings 40
spaced from each other along the length of the nozzle in
correspondence with the wafers W. Each of the nozzle holes 40
extends radially through the pipe from the main nozzle
passageway.
[0034] In a first embodiment (case 1 of FIG. 6), the inner diameter
(parameter B) of each de-ionized water supply nozzle 34 was
1.8.about.2.3 mm, each set of de-ionized water supply nozzle holes
was made up of twelve (12) individual nozzle holes 40, and the
diameter of each of the nozzle holes was .about.0.8.+-.0.005 mm
(parameter C). Furthermore, each set of nozzles holes 40 subtended
an angle (parameter D) of 90.degree. from the axial center of the
nozzle 34 such that the deionized water issuing from each set of
nozzle holes 40 is sprayed in at an angle of 90.degree. from the
nozzle 34.
[0035] Also, during the rinsing procedure, the deionized water in
the chamber 30 is discharged from the cleaning chamber 30 in a
weight % ratio (parameter E)=E1:E2, wherein E1+E2 equals the weight
(100%) of the water that is being fed through the nozzles 34, E1 is
the weight % of the liquid that is discharged from the bottom of
the cleaning chamber 30, and E2 is the weight % of the liquid that
is discharged as overflowing the chamber 30. In the first
embodiment, liquid in an amount of about 70 weight % (E1) of the
de-ionized water that is being supplied by the nozzles 34 is
discharged from the cleaning chamber 30 through the bottom of the
cleaning chamber 30, while liquid in an amount of about 30 weight %
(E2) of the de-ionized water that is being supplied by the nozzles
34 is discharged as overflowing the chamber 30.
[0036] Also, in this embodiment, the apparatus is provided with
only one discharge pipe (parameter F) connected to the bottom of
the cleaning chamber 30 and through which the deionized water is
drained from the chamber 30 during the rinsing procedure. Still
further, the deionized water is supplied through the nozzles 34 at
a supply rate (parameter A) of 36 l/min.
[0037] This embodiment, as shown in the graph of FIG. 6, produces a
remarkably smaller E/R difference (difference in etching rates at
upper and lower portions of the vertically oriented wafers in the
chamber 30), and yields wafers having fewer particle defects, as
compared with the results of the conventional cleaning system
comprising an in-line array of washing tubs.
[0038] The second embodiment of the invention (case 2) was
identical to the first embodiment in terms of the parameters A, C
and D. However, the inner diameter (parameter B) of each de-ionized
water supply nozzle 34 was 1.0.+-.0.1 mm, and the weight % ratio
(E=E1:E2) was 80 weight %:20 weight %. Also, this embodiment
included two discharge pipes (parameter F) for discharging the
de-ionized water from the bottom of the chamber 30 the second
discharge pipe is represented in FIG. 4 by the second reference
numeral (38).
[0039] The third embodiment (case 3) had the same parameters D and
F as the second embodiment. However, the supply rate (parameter A)
was set at 30 l/min, the inner diameter (parameter B) of each
de-ionized water supply nozzle 34 was 0.8.+-.0.05 mm, the diameter
of each of the nozzle holes (parameter C) was 0.5.+-.0.05 mm, and
the deionized water in the chamber 30 was discharged from the
cleaning chamber 30 in a weight % ratio (parameter E)=E1:E2 of 90
weight %:10 weight %. As the graph of FIG. 6 clearly chows, the
third embodiment produced a remarkably lower etching rate
difference and fewer particle defects in comparison with the second
embodiment.
[0040] The fourth embodiment of the invention (case 4) had the same
parameters B, C and F as the third embodiment. However, the supply
rate (parameter A) was set at 19 l/min, each set of nozzles holes
40 sprayed the de-ionized water at an angle (parameter D) of
95.degree., and E-1 in the condition E has a weight ratio 95(%) and
the deionized water in the chamber 30 was discharged from the
cleaning chamber 30 in a weight % ratio (parameter E)=E1:E2 of 95
weight %:5 weight %. Although this embodiment produces uniformity
in the etching rates from the upper to the lower parts of the
vertically oriented wafers W, it allows for more particle defects
than the third embodiment.
[0041] The fifth embodiment of the present invention had the same
parameters B, C, E, F of the fourth embodiment. However, the supply
rate (parameter A) was set at 24 l/min, and the de-ionized water
was sprayed at an angle of 90.degree. (parameter D) onto the wafers
W. The fifth embodiment yielded similar results, in terms of
etching rate difference, to the fourth embodiment but yielded a
remarkably fewer number of particle defects.
[0042] As described above, according to an exemplary embodiment of
the present invention, the tubular de-ionized water supply nozzles
34 extend longitudinally in the direction in which the wafers are
spaced from each other, and to the sides of the wafers W within the
cleaning chamber 30. Each de-ionized water supply nozzle 34 has an
inner nozzle passageway, and a plurality of sets of five nozzle
holes 40 extending radially through the main body of the nozzle
from the inner nozzle passageway. Each such set of nozzle holes 40
subtends an angle of 80.about.100.degree. in a vertical plane and
is directed towards a surface of a respective wafer W. The inner
nozzle passageway of each de-ionized water supply nozzle 34 has a
diameter of 0.8.+-.0.05 mm, whereas the nozzle holes 40 each have a
diameter of 0.5.+-.0.05 mm.
[0043] A control means, e.g., controller and valves, regulates the
amount of the de-ionized water sprayed into the chamber through the
de-ionized water nozzles 34 to 21.about.26 l/min. The control means
also controls the discharging of the liquid from the cleaning
chamber such liquid in an amount of 92-97 weight % of the
de-ionized water that is being supplied by the nozzles 34 into the
cleaning chamber 30 is simultaneously discharged from the cleaning
chamber 30 through the lower part of the cleaning chamber 30, while
liquid in an amount of 3-8 weight % of the de-ionized water that is
being supplied by the nozzles 34 is simultaneously discharged as
overflowing the cleaning chamber 30. The discharging of the liquid
from the lower part of the leaning chamber 30 takes place at least
two locations aligned in the direction in which the wafers W are
spaced from each other on the support 32 in the chamber 30 so that
the draining of the cleaning chamber 30 effects the wafers W more
uniformly.
[0044] This primary rinse procedure is carried out for a given
period of time, i.e., until the concentration of the cleaning
solution in the cleaning chamber 30 becomes low. A secondary rinse
procedure is performed after this primary rinse procedure. In this
secondary rinse procedure, the de-ionized water continues to be
supplied through the de-ionized supply nozzles 34 while the liquid
is discharged through the lower part of the cleaning chamber 30 at
a higher rate. Accordingly, the spraying of the de-ionized water
prevents the wafers W from being exposed to the air as the level of
the liquid in the cleaning chamber 30 drops below that of the
wafers W in the cleaning chamber 30. Also, once the wafers W become
disposed above the surface of the liquid in the cleaning chamber
30, isopropyl alcohol (IPA) vapors are introduced into the cleaning
chamber 30 and the de-ionized water continues to be supplied. The
supplying of the de-ionized water is terminated after a
predetermined period of time, thereby completing the secondary
rinse procedure, whereupon a drying procedure begins.
[0045] Although the present invention has been described above in
connection with certain preferred embodiments thereof, various
changes to these embodiments will be apparent to those skilled in
the art. Therefore, all such modifications and variations of the
disclosed embodiments are sent o be within the true spirit and
scope of the invention as defined by the appended claims.
* * * * *