U.S. patent application number 12/204757 was filed with the patent office on 2009-03-05 for polishing apparatus and method for polishing semiconductor wafers using load-unload stations.
Invention is credited to In-Kwon Jeong.
Application Number | 20090061739 12/204757 |
Document ID | / |
Family ID | 40408209 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090061739 |
Kind Code |
A1 |
Jeong; In-Kwon |
March 5, 2009 |
POLISHING APPARATUS AND METHOD FOR POLISHING SEMICONDUCTOR WAFERS
USING LOAD-UNLOAD STATIONS
Abstract
A polishing apparatus and method for polishing semiconductor
wafers uses multiple load-unload stations and at least one
turn-over robotic wafer handing device to process the wafers so
that the wafer can be polished at multiple polishing tables. The
turn-over robotic wafer handing device operates to turn over the
wafers so that one side of the wafers can be polished at a first
polishing table and the other side of the wafers can then be
polished at a second polishing table.
Inventors: |
Jeong; In-Kwon; (Cupertino,
CA) |
Correspondence
Address: |
Wilson & Ham
PMB: 348, 2530 Berryessa Road
San Jose
CA
95132
US
|
Family ID: |
40408209 |
Appl. No.: |
12/204757 |
Filed: |
September 4, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60967472 |
Sep 5, 2007 |
|
|
|
Current U.S.
Class: |
451/41 ;
451/103 |
Current CPC
Class: |
B24B 37/345
20130101 |
Class at
Publication: |
451/41 ;
451/103 |
International
Class: |
B24B 7/30 20060101
B24B007/30; B24B 31/00 20060101 B24B031/00 |
Claims
1. A polishing apparatus comprising: first and second polishing
units, each of the first and second polishing units being
configured to polish one side of semiconductor wafers, each of the
first and second polishing units comprising: a polishing table; and
a wafer carrier assembly configured to hold a semiconductor wafer
and move the semiconductor wafer to and from the polishing table,
the wafer carrier assembly being further configured to move the
semiconductor wafer onto the polishing table; first, second, third
and fourth load-unload stations, each of the first, second, third
and fourth load-unload stations being configured to accommodate one
of the semiconductor wafers at a time, the first and second
load-unload stations being situated such that the first polishing
unit is positioned between the first and second load-unload
stations, the third and fourth load-unload stations being situated
such that the second polishing unit is positioned between the third
and fourth load-unload stations; and a turn-over robotic wafer
handing device positioned between the second and third load-unload
stations, the turn-over robotic wafer handing device being
configured to transfer the semiconductor wafer from the second
load-unload station to the third load-unload station, the turn-over
robotic wafer handing device being further configured to turn over
the semiconductor wafer when the semiconductor wafer is transferred
from the second load-unload station to the third load-unload
station.
2. The apparatus of claim 1 wherein the first, second, third and
fourth load-unload stations are all arranged in a linear
manner.
3. The apparatus of claim 1 wherein at least one of the first,
second, third and fourth load-unload stations is configured to
spray fluid onto a wafer carrier of the wafer carrier assembly or
the semiconductor wafer when the wafer carrier or the semiconductor
wafer is positioned at that load-unload station.
4. The apparatus of claim 1 further comprising a washing station
positioned between the first and fourth load-unload stations, the
washing station being configured to spray fluid onto a wafer
carrier of the wafer carrier assembly when the wafer carrier is
positioned over the washing station.
5. The apparatus of claim 4 wherein the washing station is
positioned between the first load-unload station and the polishing
table of the first polishing unit, between the polishing table of
the first polishing unit and the second load-unload station,
between the third load-unload station and the polishing table of
the second polishing unit, or between the polishing table of the
second polishing unit and the fourth load-unload station.
6. The apparatus of claim 1 wherein the wafer carrier assembly of
the first polishing unit is configured to be moved between the
first load-unload station, the polishing table of the first
polishing unit and the second load-unload station, and wherein the
wafer carrier assembly of the second polishing unit is configured
to be moved between the third load-unload station, the polishing
table of the second polishing unit and the fourth load-unload
station.
7. The apparatus of claim 1 wherein the wafer carrier assembly of
the first polishing unit is configured to be moved between the
first load-unload station, the polishing table of the first
polishing unit and the third load-unload station, and wherein the
wafer carrier assembly of the second polishing unit is configured
to be moved between the third load-unload station, the polishing
table of the second polishing unit and the fourth load-unload
station.
8. The apparatus of claim 1 wherein the wafer carrier assembly of
the first polishing unit is configured to be moved between the
first load-unload station, the polishing table of the first
polishing unit and the second load-unload station, and wherein the
wafer carrier assembly of the second polishing unit is configured
to be moved between the second load-unload station, the polishing
table of the second polishing unit and the fourth load-unload
station.
9. The apparatus of claim 1 further comprising: another first,
second, third and fourth load-unload stations, the another first
and second load-unload stations being situated such that the first
polishing unit is positioned between the another first and second
load-unload stations, the another third and fourth load-unload
stations being situated such that the second polishing unit is
positioned between the another third and fourth load-unload
stations, wherein each of the first and second polishing units
further comprises another wafer carrier assembly configured to hold
another semiconductor wafer and move the another semiconductor
wafer to and from the polishing table, the wafer carrier assembly
being further configured to polish the another semiconductor wafer
on the polishing table.
10. The apparatus of claim 9 wherein the another first, second,
third and fourth load-unload stations are all arranged in a linear
manner.
11. The apparatus of claim 9 wherein the turn-over robotic wafer
handing device is further configured to transfer the another
semiconductor wafer from the another second load-unload station to
the another third load-unload station.
12. The apparatus of claim 9 further comprising another turn-over
robotic wafer handing device positioned between the another second
load-unload station and the another third load-unload station, the
another turn-over robotic wafer handing device being configured to
transfer the another semiconductor wafer from the another second
load-unload station to the another third load-unload station.
13. A method for polishing semiconductor wafers, the method
comprising: moving a semiconductor wafer between a first
load-unload station, a first polishing table and a second
load-unload station on a first wafer carrier assembly, including
polishing a first side of the semiconductor wafer on the first
polishing table using the first wafer carrier assembly; moving the
semiconductor wafer between a third load-unload station, a second
polishing table and a fourth load-unload station on a second wafer
carrier assembly, including polishing a second side of the
semiconductor wafer on the second polishing table using the second
wafer carrier assembly; and transferring the semiconductor wafer
from the second load-unload station to the third load-unload
station using a turn-over robotic wafer handing device, including
turning over the semiconductor wafer when the semiconductor wafer
is transferred from the second load-unload station to the third
load-unload station.
14. The method of claim 13 wherein the moving the semiconductor
wafer between the first load-unload station, the first polishing
table and the second load-unload station includes linearly moving
the first wafer carrier assembly between the first load-unload
station, the first polishing table and the second load-unload
station of the first polishing unit.
15. The method of claim 13 further comprising: moving another
semiconductor wafer between another first load-unload station, the
first polishing table and another second load-unload station on
another first wafer carrier assembly, including polishing a first
side of the another semiconductor wafer on the first polishing pad
using the another first wafer carrier assembly; and moving the
another semiconductor wafer between another third load-unload
station, the second polishing table and another fourth load-unload
station on another second wafer carrier assembly, including
polishing a second side of the another semiconductor wafer on the
second polishing table using the another second wafer carrier
assembly.
16. The method of claim 15 wherein the moving the another
semiconductor wafer between the another first load-unload station,
the first polishing table and the another second load-unload
station includes linearly moving the another first wafer carrier
assembly between the another first load-unload station, the first
polishing table and the another second load-unload station.
17. The method of claim 15 further comprising transferring the
another semiconductor wafer from the another second load-unload
station to the another third load-unload station using the
turn-over robotic wafer handing device.
18. The method of claim 15 further comprising transferring the
another semiconductor wafer from the another second load-unload
station to the another third load-unload station using another
turn-over robotic wafer handing device.
19. The method of claim 13 further comprising: transferring the
semiconductor wafer from a wafer storage station to a buffer
station; transferring the semiconductor wafer from the buffer
station to the first load-unload station; transferring the
semiconductor wafer from the fourth load-unload station to a wafer
cleaner; and transferring the semiconductor wafer from the wafer
cleaner to the wafer storage station.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is entitled to the benefit of U.S.
Provisional Patent Application Ser. No. 60/967,472, filed on Sep.
5, 2007, which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to semiconductor processing
equipments, and more particularly to a polishing apparatus and
method for polishing semiconductor wafers.
BACKGROUND OF THE INVENTION
[0003] Wet cleaning methods that use liquid chemicals have been
used to remove particles from both sides of semiconductor wafers.
However, particles embedded in the semiconductor wafers are not
easily removed by conventional wet cleaning methods.
[0004] Chemical Mechanical Polishing (CMP) technology, which is
used to planarize surfaces of semiconductor wafers, can be used to
remove such particles. In general, a conventional CMP apparatus
includes a polishing table where a polishing pad is placed, and a
wafer carrier that supports a semiconductor wafer, which is
polished by pressing the wafer against the polishing pad. The CMP
apparatus also includes a wafer cleaner to clean and dry the
polished wafers.
[0005] However, the conventional CMP apparatus is designed to
polish only the front sides of the semiconductor wafers, which are
the sides where semiconductor devices are formed on the wafers, in
order to planarize surface layers deposited on the front sides of
the wafers. Thus, if the conventional CMP apparatus is to be used
to remove particles from both sides of the semiconductor wafers,
the wafers must be processed twice in the CMP apparatus to polish
both sides of the wafers.
[0006] In order to polish the front sides of the wafers, the wafers
are loaded into the CMP apparatus and then polished such that the
front sides of the wafers are polished. The polished wafers are
then cleaned and dried in the wafer cleaner before the wafers are
removed from the CMP apparatus. In order to polish the backsides of
the wafers, the wafers removed from the CMP apparatus must be
loaded into the CMP apparatus again and then polished such that the
backsides of the wafers are polished. The polished wafers must then
be cleaned and dried again in the wafer cleaner before the wafers
are removed from the CMP apparatus.
[0007] In view of this issue, what is needed is a polishing
apparatus and method for polishing semiconductor wafers that can
polish both sides of the wafers in a more efficient manner.
SUMMARY OF THE INVENTION
[0008] A polishing apparatus and method for polishing semiconductor
wafers uses multiple load-unload stations and at least one
turn-over robotic wafer handing device to process the wafers so
that the wafer can be polished at multiple polishing tables. The
turn-over robotic wafer handing device operates to turn over the
wafers so that one side of the wafers can be polished at a first
polishing table and the other side of the wafers can then be
polished at a second polishing table.
[0009] A polishing apparatus in accordance with an embodiment of
the invention comprises first and second polishing units, first,
second, third and fourth load-unload stations and a turn-over
robotic wafer handing device. Each of the first and second
polishing units is configured to polish one side of semiconductor
wafers. Each of the first and second polishing units comprises a
polishing table and a wafer carrier assembly configured to hold a
semiconductor wafer and move the semiconductor wafer to and from
the polishing table. The wafer carrier assembly is further
configured to move the semiconductor wafer onto the polishing
table. Each of the first, second, third and fourth load-unload
stations is configured to accommodate one of the semiconductor
wafers at a time. The first and second load-unload stations are
situated such that the first polishing unit is positioned between
the first and second load-unload stations. The third and fourth
load-unload stations are situated such that the second polishing
unit is positioned between the third and fourth load-unload
stations. The turn-over robotic wafer handing device is positioned
between the second and third load-unload stations. The turn-over
robotic wafer handing device is configured to transfer the
semiconductor wafer from the second load-unload station to the
third load-unload station. The turn-over robotic wafer handing
device is further configured to turn over the semiconductor wafer
when the semiconductor wafer is transferred from the second
load-unload station to the third load-unload station.
[0010] A method for polishing semiconductor wafers in accordance
with an embodiment of the invention comprises moving a
semiconductor wafer between a first load-unload station, a first
polishing table and a second load-unload station on a first wafer
carrier assembly, including polishing a first side of the
semiconductor wafer on the first polishing table using the first
wafer carrier assembly, moving the semiconductor wafer between a
third load-unload station, a second polishing table and a fourth
load-unload station on a second wafer carrier assembly, including
polishing a second side of the semiconductor wafer on the second
polishing table using the second wafer carrier assembly, and
transferring the semiconductor wafer from the second load-unload
station to the third load-unload station using a turn-over robotic
wafer handing device, including turning over the semiconductor
wafer when the semiconductor wafer is transferred from the second
load-unload station to the third load-unload station.
[0011] Other aspects and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, illustrated by way of
example of the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a top view of a polishing apparatus in accordance
with an embodiment of the present invention.
[0013] FIG. 2 is a side view of polishing units and load-unload
stations of a polishing station of the polishing apparatus of FIG.
1, illustrating how wafer carrier assemblies of the polishing units
linearly move to transfer semiconductor wafers.
[0014] FIG. 3 is a top view of a load-unload station in accordance
with an embodiment of the invention, which can be used in the
polishing apparatus of FIG. 1.
[0015] FIG. 4 is a cross-sectional view of the load-unload station
of FIG. 3.
[0016] FIGS. 5(a) and 5(b) are sequential cross-sectional views of
the load-unload station of FIG. 3 to show a sequence of loading a
semiconductor wafer W onto a wafer carrier.
[0017] FIG. 6 is a top view of a polishing station in accordance
with an alternative embodiment of the present invention.
[0018] FIGS. 7 and 8 are top view of a wafer turn-over device in
accordance with an embodiment of the invention, which shows a
semiconductor wafer being transferred between two load-unload
stations of the polishing apparatus of FIG. 1 such that the
semiconductor wafer is also turned over.
[0019] FIG. 9 is a cross-sectional view of the wafer turn-over
device of FIGS. 7 and 8.
[0020] FIG. 10 is a top view of the wafer turn-over device in
accordance with another embodiment of the invention.
[0021] FIG. 11 is a top view of a polishing station in accordance
with another alternative embodiment of the present invention.
[0022] FIG. 12 is a top view of a washing station of the polishing
station of FIG. 11 in accordance with an embodiment of the
invention.
[0023] FIG. 13 is a flow diagram of a method of polishing
semiconductor wafers in accordance with an embodiment of the
invention.
DETAILED DESCRIPTION
[0024] With reference to FIGS. 1 and 2, a polishing apparatus 10 in
accordance with an embodiment of the present invention is
described. FIG. 1 is a top view of the polishing apparatus 10. FIG.
2 is a side view of a polishing station 20 of the polishing
apparatus 10. The polishing apparatus 10 comprises the polishing
station 20, a wafer storage station 102, an input buffer station
105, a first wafer transport device 150, a second wafer transport
device 160, a third wafer transport device 210, a first wafer
cleaner 220, and a second wafer cleaner 220'.
[0025] The polishing station 20 is an enclosed structure with
window-like mechanisms (not shown) that can be opened to transfer
semiconductor wafers into and out of the polishing station 20. The
polishing station 20 comprises a first polishing unit 250a, a
second polishing unit 250b, first two load-unload stations 15a and
15a', second two load-unload stations 15b and 15b', third two
load-unload stations 15c and 15c', fourth two load-unload stations
15d and 15d', and a wafer turn-over device 50. In the following
description, similar components will sometimes be referred to
herein using their common reference numbers without the letter
suffixes.
[0026] Each polishing unit 250 of the polishing station 20
comprises a polishing table 256, a first wafer carrier assembly 260
and a second wafer carrier assembly 260'. The polishing table 256
can be used to simultaneously polish two semiconductor wafers at a
time. The polishing table 256 can be rotated or orbited about an
axis. In some embodiments, a polishing pad 255 may be attached to
the polishing table 256 for chemical and mechanical polishing
process of semiconductor wafers. One or more slurries containing
abrasive particles and/or chemicals, such as potassium hydroxide
(KOH), may be used with the polishing pad 255 to polish
semiconductor wafers. Each polishing unit 250 may further comprise
a pad conditioner (not shown) to condition the surface of the
polishing pad 255 during the polishing process to refresh the
surface of the polishing pad for proper polishing.
[0027] Each wafer carrier assembly 260 of the polishing units 250a
and 250b comprises a wafer carrier 262, a carrier shaft 264 and a
rotational-and-vertical drive mechanism 266, as illustrated in
FIGS. 1 and 2. The wafer carrier 262 is designed to hold a
semiconductor wafer such that the surface of the wafer to be
polished is faced toward the polishing pad 255. The wafer carrier
262 is connected to the rotational-and-vertical drive mechanism 266
through the carrier shaft 264. The rotational-and-vertical drive
mechanism 266 controls the rotational and vertical motions of the
wafer carrier 262 through the connected carrier shaft 264. Thus,
the rotational-and vertical drive mechanism 266 is configured to
rotate the wafer carrier 262 by rotating the connected carrier
shaft 264 and to vertically move the wafer carrier 262 by
vertically moving the connected carrier shaft 264. In order to
polish semiconductor wafers, the wafer carriers 262 are moved down
or lowered to the respective polishing pads 255 by the respective
rotating-and-vertical mechanisms 266 to press the wafers held by
the wafer carriers 262 onto the respective polishing pads 255.
[0028] The load-unload stations 15 of the polishing station 20
accommodate wafers transferred to and from the load-unload stations
15. Each of the load-unload stations 15 is configured to
accommodate one semiconductor wafer at at time. The load-unload
stations 15 are configured to receive or unload a wafer released
from a wafer carrier 262 or another device, such as the second
wafer transport device 160, and to place or load a wafer onto a
wafer carrier or another device.
[0029] The load-unload stations 15 and the two polishing units 250a
and 250b are arranged in such a manner that the first two
load-unload stations 15a and 15a' are positioned in front of the
first polishing unit 250a (i.e., closest to the second wafer
transport device 160), the second two load-unload stations 15b and
15b' are positioned between the first polishing unit 250a and the
third two load-unload stations 15c and 15c', the second polishing
unit 250b is positioned between the third two load-unload stations
15c and 15c' and the fourth two load-unload stations 15d and 15d',
and the fourth load-unload stations 15d and 15d' are positioned
behind the second polishing unit 250b, as illustrated in FIG. 1. In
addition, the load-unload stations 15a, 15b, 15c and 15d are
arranged in a linear manner, and the load-unload stations 15a',
15b', 15c' and 15d' are also arranged in a linear manner. That is,
the load-unload stations 15a, 15b, 15c and 15d are aligned along a
straight line, and the load-unload stations 15a', 15b', 15c' and
15d' are aligned along another straight line.
[0030] The polishing station 20 is configured such that (1) the
first wafer carrier assembly 260a of the first polishing unit 250a
can move in a linear manner between the first and second
load-unload stations 15a and 15b, and the first wafer carrier
assembly 260b of the second polishing unit 250b can move in a
linear manner between the third and fourth load-unload stations 15c
and 15d, and (2) the second wafer carrier assembly 260a' of the
first polishing unit 250a can move in a linear manner between the
first and second load-unload stations 15a' and 15b' and the second
wafer carrier assembly 260b' of the second polishing unit 250b can
move in a linear manner between the third and fourth load-unload
stations 15c' and 15d'.
[0031] The polishing station 20 can be also configured such that
(1) the first wafer carrier assembly 260a of the first polishing
unit 250a can also move in a linear manner between the first,
second and third load-unload stations 15a, 15b and 15c, and the
first wafer carrier assembly 260b of the second polishing unit 250b
can move in a linear manner between the second, third and fourth
load-unload stations 15b, 15c and 15d, and (2) the second wafer
carrier assembly 260a' of the first polishing unit 250a can move in
a linear manner between the first, second and third load-unload
stations 15a', 15b' and 15c' and the second wafer carrier assembly
260b' of the second polishing unit 250b can also move in a linear
manner between the second, third and fourth load-unload stations
15b', 15c' and 15d'.
[0032] In order to move the wafer carrier assemblies 260 linearly
between the load-unload stations 15, the wafer carrier assemblies
260 are connected to at least one wafer conveying device 22, as
shown in FIG. 2, which can move the wafer carrier assemblies
linearly. An example of a wafer conveying device that can be used
to linearly move the wafer carrier assemblies 260 is described in
U.S. Pat. No. 7,223,153, which is incorporated herein by
reference.
[0033] With reference to FIGS. 3-5, one of the load-unload stations
15 of the polishing station 20 is further described. FIG. 3 is a
top view of the load-unload station 15, and FIG. 4 is a
cross-sectional view of the load-unload station 15 of FIG. 3 along
the line QQ. The load-unload station 15 comprises a base 190, an
annular wall 195, a lifter 200, a wafer tray 211, first multiple
nozzles 240, second multiple nozzles 250, a drain channel 260, a
first fluid channel 270 and a second fluid channel 272. The fluid
channels 270 and 272 may be connected to fluid sources (not shown).
The drain channel 260 may be connected to a drain pump (not
shown).
[0034] The annular wall 195 and the wafer tray 211 are mounted on
the base 190. The wafer tray 211 comprises a hole at the center
such that the lifter 200 can be positioned at the center of the
base 190. The lifter 200 is connected to a lifter pneumatic
cylinder 204 through a lift piston 202, as illustrated in FIG. 4.
The lifter 200 is a wafer handling device to raise and lower a
wafer to and from a wafer carrier (also known as a polishing head),
such as one of the wafer carriers 262a, 262a', 262b and 262b'. The
lifter cylinder 204 is connected to the first fluid channel 270 and
operated by a fluid supplied through the first fluid channel 270.
The lifter 200 is moved up and down by the lifter cylinder 204.
[0035] The lifter 200 is lifted above the top surface of the
annular wall 195 to a wafer transfer position, as illustrated in
FIG. 4, to receive a semiconductor wafer W from a wafer transport
device, such as the second wafer transport device 160, from a wafer
carrier, such as one of the wafer carriers 262a, 262a', 262b and
262b', or from a wafer turn-over device, such as the wafer
turn-over device 50. After the lifter 200 receives the wafer W, the
lifter is moved down below the wafer tray 211 in order to place the
wafer W on the wafer tray 211. In this fashion, the wafer W is
unloaded onto the load-unload station 15.
[0036] To transfer the wafer W from the lifter 200 to a wafer
transport device, such as the third wafer transport device 210, to
a wafer carrier, such as one of the wafer carriers 262a, 262a',
262b and 262b', or to a wafer turn-over device, such as the wafer
turn-over device 50, the lifter 200 is lifted above the top surface
of the annular wall 195 to the wafer transfer position, as
illustrated in FIG. 4.
[0037] The first multiple nozzles 240 are mounted on the top of the
base 190 and the second multiple nozzles 250 are mounted on the
interior side of the annular wall 195, as illustrated in FIG. 4.
The first and second nozzles 240 and 250 are connected to the
second fluid channel 272 and used to spray fluid, such as deionized
(D.I.) water, which is supplied through the second fluid channel
272. Used fluid, e.g., used D.I. water, is drained through the
drain channel 260 by the drain pump (not shown). The first and
second multiple nozzles 240 and 250 allow the load-unload station
15 to wash a wafer and/or a wafer carrier, when one or both are
positioned at the load-unload station 15.
[0038] With reference to FIGS. 5(a) and 5(b), a process sequence
for loading a semiconductor wafer W from the load-unload station 15
of FIGS. 3 and 4 onto a wafer carrier 262, which can be one of the
wafer carriers 262a-262b' is described. FIGS. 5(a) and (b) are
sequential cross-sectional views of the load-unload station 15.
After the wafer W is positioned on the wafer tray 211 of the
load-unload station 15, as previously described with reference to
FIG. 4, the wafer carrier 262 is placed on the load-unload station
15, as illustrated in FIG. 5(a). As shown in FIG. 5(a), the wafer
carrier 262 may include a retainer ring 280 to confine the wafer W
during a polishing process. Next, the lifter 200 is moved up and
the wafer W on the lifter is received by the wafer carrier 262
using a vacuum supplied through vacuum channels 285, as illustrated
in FIG. 5(b). After the wafer W is received by the wafer carrier
262, the lifter 200 is moved down. For unloading the wafer W from
the wafer carrier 262, the vacuum provided through the vacuum
channels 285 is removed, which releases the wafer W from the wafer
carrier 262 onto the lifter 200 of the load-unload station 15. The
load-unload station 15 can then wash the wafer carrier 262 by
spraying D.I. water onto the wafer carrier 262.
[0039] Turning back to FIGS. 1 and 2, the wafer turn-over device 50
is situated between the second two load-unload stations 15b and
15b' and the third two load-unload stations 15c and 15c'. The wafer
turn-over device 50 is a robotic wafer handling device that is
configured to transfer wafers from the second two load-unload
stations 15b and 15b' to the third two load-unload stations 15c and
15c'. A robotic arm 51 of the turn-over device 50 can reach the
second two load-unload stations 15b and 15b' to pick up the wafers
from the second two load-unload stations 15b and 15b'. The robotic
arm 51 of the wafer turn-over device 50 is further configured to
turn over the wafers after it picks up the wafers from the second
two load-unload stations 15b and 15b' such that it can transfer the
wafers to the third two load-unload stations 15c and 15c' after it
turns over the wafers. As used herein, turning over a semiconductor
wafer means that the wafer is rotated 180 degrees so that major
sides or surfaces of the wafer are reversed. For example, if the
front side of the wafer is initially facing downward, the front
side of the wafer will be facing upward after the wafer is turned
over.
[0040] The wafer cleaners 220 and 220' are enclosed structures with
window-like mechanisms (not shown) that can be opened to transfer
semiconductor wafers into and out of the wafer cleaners. The first
wafer cleaner 220 comprises a wafer receiving station 222, a first
cleaning station 224, a second cleaning station 226, a drying
station 228, an output buffer station 230, a first wafer transport
device 232, a second wafer transport device 234, a third wafer
transport device 236, and a fourth wafer transport device 238. The
wafer cleaner 220 is configured to clean and dry both of the front
and back sides of the wafers. The second wafer cleaner 220' can be
identical to the first wafer cleaner 220.
[0041] The wafer cleaners 220 and 220' are situated such that the
wafer receiving stations 222 of the wafer cleaners are adjacent to
the third wafer transport device 210 and the output buffer stations
230 of the wafer cleaners are adjacent to the first wafer transport
device 150.
[0042] The wafer receiving station 222 accommodates semiconductor
wafers that are transferred by the third wafer transport device
210. The first wafer transport device 232 transfers wafers from the
wafer receiving station 222 to the first cleaning station 224. The
second wafer transport device 234 transfers wafers from the first
cleaning station 224 to the second cleaning station 226. The third
wafer transport device 236 transfers wafers from the second
cleaning station 226 to the drying station 228. The fourth wafer
transport device 238 transfers wafers from the drying station 228
to the output buffer station 230. Wafers are removed from the
output buffer station 230 by the first wafer transport device 150
and then transferred to the wafer storage station 102.
[0043] The first and second cleaning stations 224 and 226 of the
wafer cleaner 220 remove slurry particles from wafer surfaces using
D.I. water and/or chemicals, such as ammonium hydroxide
(NH.sub.4OH), diluted hydrofluoric acid (HF) and organic chemicals.
The wafer receiving station 222 can be also configured to remove
slurry particles from wafer surfaces using D.I. water and/or
chemicals, such as NH.sub.4OH, diluted HF and organic chemicals.
After the cleaning process is completed at the second cleaning
station 226, wafers are rinsed with D.I. water and then dried in
the drying station 228.
[0044] The wafer storage station 102 accommodates semiconductor
wafers or other comparable objects to be polished by the polishing
station 20. The wafer storage station 102 can also accommodate
semiconductor wafers or other comparable objects that have been
polished and cleaned by the polishing station 20 and the wafer
cleaners 220 and 220'.
[0045] The first wafer transport device 150 is situated between the
wafer storage station 102 and the input buffer station 105 and
between the wafer storage station 102 and the wafer cleaners 220
and 220', as illustrated in FIG. 1, such that a robotic arm of the
first wafer transport device 150 can transfer wafers from the wafer
storage station 102 to the input buffer station 105 and from output
buffer stations 230 of the wafer cleaners 220 and 220' to the wafer
storage station 102.
[0046] The input buffer station 105 is situated between the first
and second wafer transport devices 150 and 160. The input buffer
station 105 accommodates wafers to be polished by the polishing
station 20.
[0047] The second wafer transport device 160 is situated between
the input buffer station 105 and the first two load-unload stations
15a and 15a' of the polishing station 20, as illustrated in FIG. 1,
such that a robotic arm of the second wafer transport device 160
can transfer wafers from the input buffer station 105 to the first
load-unload stations 15a and 15a' of the polishing station 20.
Because the robotic arm of the second wafer transport device 160
can be contaminated when it enters the polishing station 20, the
second wafer transport device 160 is preferably separated from the
first wafer transport device 150 by a partition 161, as illustrated
in FIG. 1, in order to prevent the second wafer transport device
160 from contaminating the first wafer transport device 150. In
order to keep the first wafer transport device 150 clean, an air
filter unit (not shown) can be installed over the first wafer
transport device 150.
[0048] The third wafer transport device 210 is situated between the
fourth load-unload stations 15d and 15d' of the polishing station
20 and the wafer receiving stations 222 of the respective wafer
cleaners 220 and 220', as illustrated in FIG. 1, such that a
robotic arm of the third wafer transport device 210 can transfer
wafers from the fourth two load-unload stations 15d and 15d' to the
wafer receiving stations 222.
[0049] The first and third wafer transport devices 150 and 210 may
be situated on respective linear tracks 155 and 215 such that the
wafer transport devices can be moved in a linear manner on the
linear tracks by respective linear drive mechanisms (not shown).
The robotic arms of the first, second and third wafer transport
devices 150, 160 and 210 may be configured to turn over wafers
before transferring the wafers to the input buffer station 105, the
polishing station 20 and the wafer cleaners 220 and 220',
respectively.
[0050] With reference to FIGS. 1 and 2, a method of processing
semiconductor wafers in the polishing apparatus 10 according to an
embodiment of the present invention is described.
[0051] First, the first wafer transport device 150 transfers
semiconductor wafers from the storage station 102 to the input
buffer station 105.
[0052] Next, the second wafer transport device 160 transfers the
wafers from the input buffer station 105 to the first two
load-unload stations 15a and 15a' such that backsides of the
wafers, where transistors and electrical circuits are not formed,
face the first load-unload stations 15a and 15a'. That is, the
backsides of the wafers are faced downward toward the first
load-unload stations 15a and 15a'.
[0053] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the first two load-unload
stations 15a and 15a', respectively, (2) receive the wafers from
the first load-unload stations 15a and 15a', and then (3) move to
the polishing table 256a of the first polishing unit 250a.
[0054] Next, the wafer carriers 262a and 262a' move down to the
polishing pad 255a of the polishing table 256a and then polish the
wafers using a first slurry. Thus, the backsides of the wafers are
polished on the polishing pad 255a.
[0055] Next, after the wafers are polished on the polishing pad
255a, the wafer carriers 262a and 262a' move up from the polishing
pad 255a.
[0056] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the second two load-unload
stations 15b and 15b', respectively, (2) transfer the wafers to the
second load-unload stations 15b and 15b' such that the backsides of
the wafers face the second load-unload stations 15b and 15b', and
then (3) return to the first load-unload stations 15a and 15a'.
[0057] Next, the robotic arm of the wafer turn-over device 50 (1)
approaches the second load-unload station 15b, (2) picks up the
wafer from the second load-unload station 15b, (3) turns over the
wafer such that the backside of the wafer faces upward, (4)
transfers the wafer to the third load-unload station 15c such that
the front side of the wafer, where transistors and electrical
circuits are formed, faces the third load-unload station 15c, (5)
approaches the second load-unload station 15b', (6) picks up the
wafer from the second load-unload station 15b', (7) turns over the
wafer such that the backside of the wafer faces upward, (8)
transfers the wafer to the third load-unload station 15c' such that
the front side of the wafer, where transistors and electrical
circuits are formed, faces the third load-unload station 15c', and
(9) moves away from the third load-unload station 15c'.
[0058] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the third load-unload
stations 15c and 15c', respectively, (2) receive the wafers from
the third load-unload stations 15c and 15c', and then (3) move to
the polishing table 256b of the second polishing unit 250b.
[0059] Next, the wafer carriers 262b and 262b' move down to the
polishing pad 255b of the polishing table 256b and then polish the
wafers using a second slurry, whose components are different from
the first slurry. Alternatively, the first slurry used at the
polishing table 256a can be used at the polishing table 256b
instead of the second slurry. Thus, the front sides of the wafers
are polished on the polishing pad 255b.
[0060] Next, after the wafers are polished on the polishing pad
255b, the wafer carriers 262b and 262b' move up from the polishing
pad 255b.
[0061] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the fourth load-unload
stations 15d and 15d', respectively, (2) transfer the wafers to the
fourth load-unload stations 15d and 15d' such that the front sides
of the wafers face the fourth load-unload stations 15d and 15d',
and then (3) return to the third load-unload stations 15c and
15c'.
[0062] Next, the third wafer transport device 210 removes the
wafers from the fourth load-unload stations 15d and 15d' and then
transfers the wafers to the wafer receiving stations 222 of the
wafer cleaners 220 and 220', respectively. The third wafer
transport device 210 may turn over the wafers before transferring
the wafers to the wafer receiving stations 222. The wafers are then
cleaned and dried in the wafer cleaners 220 and 220'.
[0063] Next, the first wafer transport device 150 removes the
wafers from the output buffer stations 230 of the wafer cleaners
220 and 220' after the wafer have been processed in the wafer
cleaners 220 and 220'.
[0064] Next, the first wafer transport device 150 transfers the
wafers to the storage station 102.
[0065] In this embodiment, the backsides of the wafers have been
first polished in the first polishing unit 250a and then the front
sides of the wafers have been polished in the second polishing unit
250b. In an alternative embodiment, it is also possible to polish
the front sides of the wafers in the first polishing unit 250a and
then polish the backsides of the wafers in the second polishing
unit 250b. In this alternative embodiment, the wafers are
transferred to the first load-unload stations 15a and 15a' by the
second wafer transport device 160 such that the front sides of the
wafers face the first load-unload station 15a and 15b, and
transferred from the second load-unload stations 15b and 15b' to
the third load-unload stations 15c and 15c' by the wafer turn-over
device 50 such that the backsides of the wafers face the third
load-unload stations 15c and 15c'.
[0066] With reference to FIGS. 1 and 2, an alternative method of
processing semiconductor wafers in the polishing apparatus 10
according to an alternative embodiment of the present invention is
described.
[0067] First, the first wafer transport device 150 transfers
semiconductor wafers from the storage station 102 to the input
buffer station 105.
[0068] Next, the second wafer transport device 160 transfers the
wafers from the input buffer station 105 to the first two
load-unload stations 15a and 15a' such that first sides (front or
back sides) of the wafers face the first load-unload stations 15a
and 15a'.
[0069] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the first two load-unload
stations 15a and 15a', respectively, from their initial positions
over the polishing table 256a, (2) receive the wafers from the
first load-unload stations 15a and 15a', and then (3) return to the
polishing table 256a of the first polishing unit 250a.
[0070] Next, the wafer carriers 262a and 262a' move down to the
polishing pad 255a of the polishing table 256a and then polish the
wafers using a first slurry. Thus, the first sides of the wafers
are polished on the polishing pad 255a.
[0071] Next, after the wafers are polished on the polishing pad
255a, the wafer carriers 262a and 262a' move up from the polishing
pad 255a.
[0072] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the third two load-unload
stations 15c and 15c', respectively, (2) transfer the wafers to the
third load-unload stations 15c and 15c' such that the first sides
of the wafers face the third load-unload stations 15c and 15c', and
then (3) return to the first load-unload stations 15a and 15a'.
[0073] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the third load-unload
stations 15c and 15c', respectively, from their initial positions
over the polishing table 256b, (2) receive the wafers from the
third load-unload stations 15c and 15c', and then (3) return to the
polishing table 256b of the second polishing unit 250b.
[0074] Next, the wafer carriers 262b and 262b' move down to the
polishing pad 255b of the polishing table 256b and then polish the
wafers using a second slurry, whose components are different from
the first slurry. Alternatively, the first slurry used at the
polishing table 256a can be used at the polishing table 256b
instead of the second slurry. Thus, the first sides of the wafers
are again polished on the polishing pad 255b.
[0075] Next, after the wafers are polished on the polishing pad
255b, the wafer carriers 262b and 262b' move up from the polishing
pad 255b.
[0076] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the fourth load-unload
stations 15d and 15d', respectively, (2) transfer the wafers to the
fourth load-unload stations 15d and 15d' such that the first sides
of the wafers face the fourth load-unload stations 15d and 15d',
and then (3) return to the third load-unload stations 15c and
15c'.
[0077] Next, the third wafer transport device 210 removes the
wafers from the fourth load-unload stations 15d and 15d' and then
transfers the wafers to the wafer receiving stations 222 of the
wafer cleaners 220 and 220'. The third wafer transport device 210
may turn over the wafers before transferring the wafers to the
wafer receiving stations 222.
[0078] Next, the first wafer transport device 150 removes the
wafers from the output buffer stations 230 of the wafer cleaners
220 and 220' after the wafers have been processed in the wafer
cleaners 220 and 220'.
[0079] Next, the first wafer transport device 150 transfers the
wafers to the storage station 102.
[0080] With reference to FIGS. 1 and 2, another alternative method
of processing semiconductor wafers in the polishing apparatus 10
according to another alternative embodiment of the present
invention is described.
[0081] First, the first wafer transport device 150 transfers wafers
from the storage station 102 to the input buffer station 105.
[0082] Next, the second wafer transport device 160 transfers the
wafers from the input buffer station 105 to the first two
load-unload stations 15a and 15a' such that first sides (front or
back sides) of the wafers face the first load-unload stations 15a
and 15a'.
[0083] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the first two load-unload
stations 15a and 15a', respectively, from their initial positions
over the polishing table 256a, (2) receive the wafers from the
first load-unload stations 15a and 15a', and then (3) return to the
polishing table 256a of the first polishing unit 250a.
[0084] Next, the wafer carriers 262a and 262a' move down to the
polishing pad 255a of the polishing table 256a and then polish the
wafers using a first slurry. Thus, the first sides of the wafers
are polished on the polishing pad 255a.
[0085] Next, after the wafers are polished on the polishing pad
255a, the wafer carriers 262a and 262a' move up from the polishing
pad 255a.
[0086] Next, the wafer carriers 262a and 262a' of the first
polishing unit 250a (1) move linearly to the second two load-unload
stations 15b and 15b', respectively, (2) transfer the wafers to the
second load-unload stations 15b and 15b' such that the first sides
of the wafers face the second load-unload stations 15b and 15b',
and then (3) return to the first load-unload stations 15a and
15a'.
[0087] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the second load-unload
stations 15b and 15b', respectively, from their initial positions
over the polishing table 256b, (2) receive the wafers from the
second load-unload stations 15b and 15b', and then (3) return to
the polishing table 256b of the second polishing unit 250b.
[0088] Next, the wafer carriers 262b and 262b' move down to the
polishing pad 255b of the polishing table 256b and then polish the
wafers using a second slurry, whose components are different from
the first slurry. Alternatively, the first slurry used at the
polishing table 256a can be used at the polishing table 256b
instead of the second slurry. Thus, the first sides of the wafers
are again polished on the polishing pad 255b.
[0089] Next, after the wafers are polished on the polishing pad
255b, the wafer carriers 262b and 262b' move up from the polishing
pad 255b.
[0090] Next, the wafer carriers 262b and 262b' of the second
polishing unit 250b (1) move linearly to the fourth load-unload
stations 15d and 15d', respectively, (2) transfer the wafers to the
fourth load-unload stations 15d and 15d' such that the first sides
of the wafers face the fourth load-unload stations 15d and 15d',
and then (3) return to the second load-unload stations 15b and
15b'.
[0091] Next, the third wafer transport device 210 removes the
wafers from the fourth load-unload stations 15d and 15d' and then
transfers the wafers to the wafer receiving stations 222 of the
wafer cleaners 220 and 220'. The third wafer transport device 210
may turn over the wafers before transferring the wafers to the
wafer receiving stations 222.
[0092] Next, the first wafer transport device 150 removes the
wafers from the output buffer stations 230 of the wafer cleaners
220 and 220' after the wafers have been processed in the wafer
cleaners 220 and 220'.
[0093] Next, the first wafer transport device 150 transfer the
wafers to the storage station 102.
[0094] With reference to FIG. 6, a polishing station 20A in
accordance with an embodiment of the present invention is
described. FIG. 6 is a top view of the polishing station 20A. The
polishing station 20A is similar to the polishing station 20 of
FIG. 1 except that the polishing station 20A comprises two wafer
turn-over devices 50 and 50' while the polishing station 20
comprises only one wafer turn-over device 50. The polishing station
20A can be used in the polishing apparatus 10 instead of the
polishing station 20.
[0095] The first wafer turn-over device 50 of the polishing station
20A is situated between the second load-unload station 15b and the
third load-unload station 15c. The first wafer turn-over device 50
transfers wafers from the second load-unload station 15b to the
third load-unload station 15c. In operation, a robotic arm of the
first wafer turn-over device 50 approaches the second load-unload
station 15b to pick up the wafer from the second load-unload
station 15b. The robotic arm of the first wafer turn-over device 50
turns over the wafer after the wafer is picked up from the second
load-unload station 15b such that the wafer is transferred to the
third load-unload station 15c after the wafer is turned over.
[0096] The second wafer turn-over device 50' of the polishing
station 20A is situated between the second load-unload station 15b'
and the third load-unload station 15c'. The second wafer turn-over
device 50' transfers wafers from the second load-unload station
15b' to the third load-unload station 15c'. In operation, a robotic
arm of the turn-over device 50' approaches the second load-unload
station 15b' to pick up the wafer from the second load-unload
station 15b'. The robotic arm of the wafer turn-over device 50'
turns over the wafer after the wafer is picked up from the second
load-unload station 15b' such that the wafer is transferred to the
third load-unload station 15c' after the wafer is turned over.
[0097] With reference to FIG. 6, a method of processing
semiconductor wafers in the polishing apparatus 10 with the
polishing station 20A according to an embodiment of the present
invention is described. The method of processing wafers in the
polishing apparatus 10 with the polishing station 20A is similar to
the method of processing wafers in the polishing apparatus 10 with
the polishing station 20 except that the wafers are turned over and
transferred from the second load-unload station 15b to the third
load-unload station 15c by the first wafer turn-over device 50, and
the wafers are turned over and transferred from the second
load-unload station 15b' to the third load-unload station 15c' by
the second wafer turn-over device 50' in the polishing station 20A.
In contrast, the wafers are turned over and transferred from the
second load-unload stations 15b and 15b' to the third load-unload
stations 15c and 15c' by the wafer turn-over device 50 in the
polishing station 20.
[0098] With reference to FIGS. 7-9, a wafer turn-over device 55
according to an embodiment of the present invention is described.
FIG. 7 is a top view of the wafer turn-over device 55 when the
wafer turn-over device 55 is positioned over the second load-unload
station 15b to pick up a semiconductor wafer W from the second
load-unload station 15b. In FIG. 7, the backside of the wafer W is
facing downward toward the second load-unload station 15b. FIG. 8
is a top view of the wafer turn-over device 55 when the turn-over
device 55 is positioned over the third load-unload station 15c to
release the wafer onto the third load-unload station 15c. In FIG.
8, the front side of the wafer W is facing downward toward the
third load-unload station 15c. FIG. 9 is a vertical cross-sectional
view of the wafer turn-over device 55 along the line XX in FIG. 7.
The wafer turn-over device 55 can replace the wafer turn-over
device 50 in the polishing station 20 or can replace each of the
wafer turn-over devices 50 and 50' in the polishing station
20A.
[0099] The wafer turn-over device 55 comprises a first gripping
assembly 60a, a second gripping assembly 60b, a support structure
65 and a pivoting mechanism 70. The support structure 65 is
connected to the pivoting mechanism 70 such that the pivoting
mechanism 70 pivots the support structure 65 about a pivoting axis
72, as shown in FIG. 7.
[0100] The first gripping assembly 60a comprises a gripping arm
71a, grippers 72, a linear moving mechanism 73a and a stopper 74a.
The linear moving mechanism 73a is mounted to the support structure
65. The gripping arm 71a is operably coupled to the support
structure 65 at an aperture of the gripping arm 71a in a movable
manner such that the gripping arm 71a can be moved linearly along
the support structure 65 by the linear moving mechanism 73a, which
is coupled to the gripping arm 71a. The stopper 74a is mounted to
the support structure 65 such that the linear motion of the
gripping arm 71a along the support structure 65 is stopped when the
gripping arm 71a contacts the stopper 74a.
[0101] The second gripping assembly 60b comprises a gripping arm
71b, grippers 72, a linear moving mechanism 73b and a stopper 74b.
The linear moving mechanism 73b is mounted to the support structure
65. The gripping arm 71b is operably coupled to the support
structure 65 at an aperture of the gripping arm 71b in a movable
manner such that the gripping arm 71b can be moved linearly along
the support structure 65 by the linear moving mechanism 73b, which
is coupled to the gripping arm 71b. The stopper 74b is mounted to
the support structure 65 such that the linear motion of the
gripping arm 71b along the support structure 65 is stopped when the
gripping arm 71b contacts the stopper 74b.
[0102] In order to grip the wafer on the second load-unload station
15b, the gripping arms 71a and 71b are moved close to each other by
their respective linear moving mechanisms 73a and 73b, as
illustrated in FIG. 6 by the arrows M, until the gripping arms
contact their respective stoppers 74a and 74b. In order to release
the wafer onto the third load-unload station 15c, the gripping arms
71a and 71b are moved away from each other by their respective
linear moving mechanisms 73a and 73b, as illustrated in FIG. 8 by
the arrows N.
[0103] Each of the grippers 72 is configured to have a "" shape, as
illustrated in FIG. 9. The grippers 72 are mounted to their
respective gripping arms 71a and 71b such that edge region of the
wafer is confined in the "" shaped grippers when the gripping arms
are in contact with their respective stoppers 74a and 74b. It is
noted that the lifter 200 of the load-unload station 15 is lifted
to the wafer transfer position, as illustrated in FIG. 4, when the
wafer turn-over device 50 grips the wafer in the second load-unload
station 15b and when the wafer turn-over device 50 releases the
wafer onto the third load-unload station 15c.
[0104] Turning back to FIGS. 7 and 8, the pivoting mechanism 70
turns over the wafer confined by the grippers 72 by pivoting the
support structure 65 about the axis 72. The axis 72 is vertical to
the line defined by the centers 16b and 16c of the second and third
load-unload stations 15b and 15c, respectively. The axis 72 is also
configured to be parallel to the wafers positioned on the second
and third load-unload stations 15b and 15c.
[0105] The pivoting mechanism 70 may be further configured to pivot
the support structure 65 about an axis 75 that is parallel to the
line defined by the centers 16b and 16c of the second and third
load-unload stations 15b and 15c, respectively, such that the
gripping assemblies 60a and 60b are moved away from the second and
third load-unload stations 15b and 15c, as illustrated in FIG. 10.
FIG. 10 is a top view of the second and third load-unload station
15b and 15c and the wafer turn-over device 55 when the gripping
assemblies 60a and 60b are pivoted away from the second load-unload
station 15b about the axis 75.
[0106] With reference to FIG. 11, a polishing station 20B in
accordance with an embodiment of the present invention is
described. FIG. 11 is a top view of the polishing station 20B. The
polishing station 20B is similar to the polishing stations 20 and
20A except that the polishing station 20B further comprises two
washing stations 18 and 18'. Although the polishing station 20B is
shown in FIG. 11 as comprising the wafer turn-over devices 50 and
50', the polishing station 20B may comprise only the wafer
turn-over device 50, similar to the polishing station 20. The
polishing station 20B can be used in the polishing apparatus 10
instead of the polishing station 20.
[0107] The first washing station 18 is situated between the second
polishing table 256b and the fourth load-unload station 15d such
that the wafer carrier 262b of the second polishing unit 250b can
be positioned over the washing station 18. The second washing
station 18' is situated between the second polishing table 256b and
the fourth load-unload station 15d' such that the wafer carrier
262b' of the second polishing unit 250b can be positioned over the
washing station 18'.
[0108] With reference to FIG. 12, the washing station 18 in
accordance with an embodiment of the invention is described. FIG.
12 is a top view of the washing station 18. The washing station 18
is similar to the load-unload station 15 except that the washing
station does not comprise the lifter 200, the lift piston 202, the
lift cylinder 204, the wafer tray 211 and the first fluid channel
270 of the load-unload station 15. The washing station 18 is used
to wash the wafer carrier 262b of the second polishing unit 250b
when the wafer carrier 262b is positioned over the washing station
18 after the wafer carrier 262b transfers a wafer to the fourth
load-unload station 15d. In order to wash the wafer carrier 262b,
D.I. water is sprayed onto the wafer carrier 262b. The washing
station 18' is similar to the washing station 18. The washing
station 18' is used to wash the wafer carrier 262b' of the second
polishing unit 250b when the wafer carrier 262b' is positioned over
the washing station 18' after the wafer carrier 262b' transfers a
wafer to the fourth load-unload station 15d'.
[0109] In an alternative embodiment of the polishing station 20B,
the first washing station 18 is situated between the second
polishing table 256b and the third load-unload station 15c such
that the wafer carrier 262b of the second polishing unit 250b can
be positioned over the washing station 18. The second washing
station 18' is situated between the second polishing table 256b and
the third load-unload station 15c' such that the wafer carrier
262a' of the second polishing unit 250b can be positioned over the
washing station 18'.
[0110] In another alternative embodiment of the polishing station
20B, the first washing station 18 is situated between the first
polishing table 256a and the second load-unload station 15b such
that the wafer carrier 262a of the first polishing unit 250a can be
positioned over the washing station 18. The second washing station
18' is situated between the first polishing table 256a and the
second load-unload station 15b' such that the wafer carrier 262a'
of the first polishing unit 250a can be positioned over the washing
station 18'.
[0111] In another alternative embodiment of the polishing station
20B, the first washing station 18 is situated between the first
polishing table 256a and the first load-unload station 15a such
that the wafer carrier 262a of the first polishing unit 250a can be
positioned over the washing station 18. The second washing station
18' is situated between the first polishing table 256a and the
first load-unload station 15a' such that the wafer carrier 262a' of
the first polishing unit 250a can be positioned over the washing
station 18'.
[0112] With reference to FIG. 11, a method of processing
semiconductor wafers in the polishing apparatus 10 with the
polishing station 20B according to an embodiment of the present
invention is described. The method of processing wafers in the
polishing apparatus 10 with the polishing station 20B is similar to
the method of processing wafers in the polishing apparatus 10 with
the polishing station 20 or with the polishing station 20A except
that the wafer carriers 262b and 262b' are washed at the washing
stations 18 and 18', respectively, after the wafers are transferred
to the load-unload stations 15d and 15d'. In other embodiments in
which the washing stations 18 and 18' are located at other
locations, the wafer carriers 262a and 262a' or 262b and 262b' are
washed at the washing stations 18 and 18', respectively, after the
wafers are transferred to the load-unload stations 15b and 15b' by
the wafer carriers 262a and 262a' or after the wafer are
transferred to the load-unload stations 15d and 15d' by the wafer
carriers 262b and 262b'.
[0113] With reference to a process flow diagram of FIG. 13, a
method for polishing semiconductor wafers in accordance with an
embodiment of the invention is described. At block 1302, a
semiconductor wafer is moved between a first load-unload station, a
first polishing table and a second load-unload station on a first
wafer carrier assembly. In addition, at block 1302, a first side of
the semiconductor wafer is polished on the first polishing table
using the first wafer carrier assembly. At block 1304, the
semiconductor wafer is moved between a third load-unload station, a
second polishing table and a fourth load-unload station on a second
wafer carrier assembly. In addition, at block 1304, a second side
of the semiconductor wafer is polished on the second polishing
table using the second wafer carrier assembly. At block 1306, the
semiconductor wafer is transferred from the second load-unload
station to the third load-unload station using a turn-over robotic
wafer handing device. In addition, at block 1306, the semiconductor
wafer is turned over when the semiconductor wafer is transferred
from the second load-unload station to the third load-unload
station.
[0114] Although specific embodiments of the invention have been
described and illustrated, the invention is not to be limited to
the specific forms or arrangements of parts so described and
illustrated. The scope of the invention is to be defined by the
claims appended hereto and their equivalents.
* * * * *