U.S. patent application number 12/004562 was filed with the patent office on 2008-10-02 for electrolytic processing unit device, and method for electrolytic processing, washing, and drying.
This patent application is currently assigned to TOKYO SEIMITSU CO., LTD.. Invention is credited to Takashi FUJITA, Kyouji WATANABE.
Application Number | 20080237066 12/004562 |
Document ID | / |
Family ID | 39719662 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080237066 |
Kind Code |
A1 |
FUJITA; Takashi ; et
al. |
October 2, 2008 |
Electrolytic processing unit device, and method for electrolytic
processing, washing, and drying
Abstract
An electrolytic processing unit device includes an electrolytic
processor for performing electrolytic processing on a wafer, a
washer for washing the processed wafer, and a drier for drying the
wafer. The electrolytic processor, the washer, and the drier are
placed in one processing chamber to form one module. In this
manner, the electrolytic processing procedure, the washing
procedure, and the drying procedure for wafers can be continuously
carried out in one place.
Inventors: |
FUJITA; Takashi; (Tokyo,
JP) ; WATANABE; Kyouji; (Tokyo, JP) |
Correspondence
Address: |
PAUL A. FATTIBENE;FATTIBENE & FATTIBENE
2480 POST ROAD
SOUTHPORT
CT
06890
US
|
Assignee: |
TOKYO SEIMITSU CO., LTD.
|
Family ID: |
39719662 |
Appl. No.: |
12/004562 |
Filed: |
December 21, 2007 |
Current U.S.
Class: |
205/799 ;
204/194 |
Current CPC
Class: |
H01L 21/6723 20130101;
H01L 21/67219 20130101; B23H 5/08 20130101; H01L 21/67028 20130101;
H01L 21/32125 20130101; H01L 21/02074 20130101 |
Class at
Publication: |
205/799 ;
204/194 |
International
Class: |
C25F 3/00 20060101
C25F003/00; C25F 7/00 20060101 C25F007/00; C25F 1/00 20060101
C25F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2007 |
JP |
2007-079961 |
Claims
1. An electrolytic processing unit device comprising: an
electrolytic processor that performs electrolytic processing on a
wafer; a washer that washes the processed wafer; and a drier that
dries the processed or washed wafer, the electrolytic processor,
the washer, and the drier being placed in a processing chamber to
form one module that performs the electrolytic processing, washing,
and drying for the wafer.
2. The electrolytic processing unit device according to claim 1,
wherein the electrolytic processor, the washer, and the drier are
aligned on a circular arc or a straight line.
3. The electrolytic processing unit device according to claim 1 or
2, wherein the electrolytic processor, the washer, and the drier
form one module, and are connected to each other by one
transportation system.
4. The electrolytic processing unit device according to any of
claims 1 through 3, wherein the electrolytic processor, the washer,
and the drier that carry out the above series of procedures are
controlled, operated, and subjected to maintenance independently of
one another.
5. The electrolytic processing unit device according to claim 1 or
2, wherein a beveling unit for beveling an outer peripheral portion
of the wafer after the electrolytic processing is provided in the
vicinity of the electrolytic processor.
6. The electrolytic processing unit device according to any of
claims 1, 3, and 4, wherein the module includes: an access area
through which wafers are brought in and out; an electrolytic
processing head for electrolytic processing that is provided in a
different area from the access area, and a holding arm that holds
the electrolytic processing head; and a washing arm that supports a
wafer washing unit is provided in the opposite position from the
holding arm.
7. The electrolytic processing unit device according to claim 6,
wherein the wafer washing unit in the module includes a washing
brush, a ultrasonic water supplier, and a nitrogen blower.
8. An electrolytic processing unit device comprising: an
electrolytic processor that performs electrolytic processing on a
wafer; a washer that washes the processed wafer; and a drier that
dries the processed or washed wafer, the electrolytic processor,
the washer, and the drier being placed in a processing chamber to
form one module that performs the electrolytic processing, washing,
and drying for the wafer, an electrode portion for the electrolytic
processing being made of an inorganic material.
9. A method for electrolytic processing, washing, and drying in a
structure having a wafer chuck mechanism, comprising the steps of:
performing electrolytic processing by applying a voltage between an
electrode having edges clamped around a wafer and an electrolytic
processing head that scans the surface of the wafer, after securing
the wafer; polishing a conductive film at an edge portion in the
same position, if necessary, while a bottom face of the wafer is
being sucked and fixed after an edge clamp is removed; scanning the
surface of the wafer with a washing arm in the same position, a
washing unit being attached to the washing arm; washing the
processed wafer; and drying the processed or washed wafer in the
same position.
10. The method according to claim 9, wherein the surface of the
wafer and an electrode portion are rinsed with pure water, after
the electrolytic processing procedure and the washing procedure.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an electrolytic processing
unit device, and a method for electrolytic processing, washing, and
drying. More particularly, the present invention relates to an
electrolytic processing unit device that is used for performing
electrolytic processing, washing, and drying for wafers, and a
method for the electrolytic processing, washing, and drying.
[0003] 2. Description of the Related Art
[0004] In a conventional CuCMP electrolytic polishing, for example,
the series of procedures for electrolytic processing, washing, and
drying for each wafer is carried out in modules that are
independent of one another. Therefore, each wafer needs to be
transported through the corresponding module in each of the
procedures for electrolytic processing, washing, and drying.
Accordingly, the number of wafer transporting procedures between
the modules is large.
[0005] Particularly, in the electrolytic processing for each wafer,
the wafer transportation system becomes more complicated, as the
wafer is normally turned over so as to process both sides of the
wafer.
[0006] If some trouble is caused in one of the modules while a
wafer is being transported sequentially to the respective modules
of the respective procedures for performing electrolytic polishing
on the wafer, the trouble leads to a large problem. For example, if
trouble is caused in the module of the washing procedure during a
processing operation, and the operator does not notice the trouble
and cannot cope with the trouble immediately, the wafer
transportation system is stopped in the module of the washing
procedure, and this delay affects the modules of the other
procedures. As the transportation systems of the other modules are
also stopped, all the wafers being transported along the process
line are stopped. The stopped wafers are left in contact with the
outer air and the process liquids over a long period of time, and
problems such as oxidation degradation and corrosion are
caused.
[0007] To avoid the above problems, there has been a method
suggested for activating the program for production control so as
to immediately stop the transportation of wafers in the modules of
all the procedures and keep the wafers away from the process line
when trouble is caused during the electrolytic processing procedure
(see Japanese Patent Application No. 2002-178236, for example).
[0008] However, creation of the above program is very complicated
according to a method such as the above described method by which
the transportation of wafers in the modules is immediately stopped
and the wafers are kept away from the process line when trouble is
caused. In a conventional CMP device, mechanical processing is
performed mostly on wafers, and a platen for rotating the wafer
polishing pad is required. However, an electrolytic processing
device does not require the platen.
[0009] If there is trouble in the last drying procedure in a case
where an operation is performed in modules for procedures of
processing, washing, and drying in a device, many wafers are
stopped within the device unless the trouble is eliminated.
Particularly, if wafers are stopped and left in the processing
procedure and the washing procedure, the surfaces of the wafers
might be oxidized, or the surfaces might be etched by the washing
solution. As a result, the quality of the wafers might be degraded.
In such a case, if even very small trouble caused in the initial
stage is left unnoticed and wafers are stopped in the device, all
the wafers in the device might be wasted, which is a serious
problem.
[0010] In view of these facts, since trouble in one of the modules
for procedures greatly affects the other wafers when a large number
of wafers are processed at once, close attention needs to be paid
to operations of the device. Therefore, unmanned operations have
been impossible in practice.
[0011] In a Cu low-k process, the atmosphere in the wafer
electrolytic processor needs to be made different from the air, so
as to prevent oxidation of the surface of the wafer especially
during the electrolytic processing. Further, in the drying
procedure after the washing, the atmosphere in the electrolytic
processor also needs to be made different from the air, so as to
reduce watermarks.
[0012] If the atmosphere control is performed in many modules, the
atmosphere controller becomes very large in size. Also, if the
atmosphere control is performed every time a wafer is brought in or
out in each procedure, a very long period of time is required. If
the atmosphere control needs to be performed only once for the
series of procedures for processing, washing, and drying, a very
efficient operation can be realized.
[0013] Where two or more modules are prepared for two or more
procedures, devices for transporting each wafer between the modules
are necessary. Those transporting devices are very costly.
Moreover, at the time of maintenance, all the procedures for wafers
are interrupted, and the operation rate of the device becomes
lower.
[0014] Further, in a conventional electrolytic processing
operation, it has been difficult to perform Cu electrolytic
processing and Ta electrolytic processing on each wafer in the same
position.
[0015] Even in electrolytic processing, a mechanism for
energization is provided in a chemical mechanical polishing device
to perform electrolytic processing. As the pad for chemical
mechanical polishing, a regular polishing pad is used. However,
when Ta polishing is performed after Cu polishing, the Cu polishing
waste adversely affects the Ta polishing. For example, the Ta
polishing rate might change, or the Cu polishing waste might adhere
to the Ta surface. Also, in a case where the electrolytic solution
for Cu polishing is different from the electrolytic solution for Ta
polishing, the two electrolytic solutions might be mixed with each
other on the polishing pad. Therefore, in a case where electrolytic
polishing is performed with a polishing pad, it is difficult to
perform both Cu polishing and Ta polishing in one module.
[0016] Likewise, in a case where the polishing procedure and the
polishing procedure are carried out in one module, electrolytic
solutions and abrasive grains existing on the polishing pad cause
the washing environment to deteriorate.
[0017] As disclosed in U.S. Pat. No. 7,084,064 and Japanese Patent
Application Laid-open No. 2006-135045, it has been almost
physically impossible to combine an electrolytic processing device
and a washing device into one by conventional techniques. This is
because an electrolytic processing device has a platen, and
processes the entire surface of each wafer at once. Normally, a
wafer is held by a wafer head provided above the wafer, and a
platen is placed under the wafer. In this case, polishing is
performed, with the wafer being held to face downward.
[0018] The wafer may be also washed while facing downward, but a
washing solution cannot be applied to the surface of the wafer in
this situation in reality.
[0019] In an electrolytic processing device disclosed in Japanese
Patent Application Laid-open No. 2002-93761, the electrode portion
is processed above a wafer while being swept. However, since each
wafer is processed while being immersed in an electrolytic
solution, it is difficult to incorporate the washing procedure and
the drying procedure into the electrolytic processing
procedure.
[0020] To combine an electrolytic processing device, a washing
device, and a drying device, the same technique should be utilized
for clamping wafers in those devices. Also, to transport wafers to
wafer chucks, a transportation mechanism that does not physically
interfere with the electrolytic processing unit, the washing unit,
and the likes needs to be prepared.
[0021] However, it has been impossible to realize all of those
functions, and combine all the modules into one module structure.
Also, it has been physically difficult to combine the modules for
supplying electrolytic solutions, controlling electrolytic
processing, and washing wafers, into one.
[0022] Also, if a polishing slurry or the like remains in the unit
for electrolytic processing, the polishing slurry dries and adheres
to the wall faces of external units. The dry polishing slurry turns
into power dust that lies scattered about in the module. As a
result, it is difficult to keep a clean environment for the washing
device.
[0023] In view of these facts, an electrolytic processing device
and washing and drying devices for washing and drying each wafer to
a normal state before each wafer is sent back to the semiconductor
factory cannot be placed in one module by conventional techniques.
If those devices are forced into one module, a clean environment
cannot be kept.
[0024] Also, if trouble is caused in one of the procedures of
electrolytic processing, washing, and drying for wafers in a case
where those procedures are combined into one module, the
transportation of wafers being transported in other modules is not
stopped. If the other wafers are stopped, the surface of each wafer
is reformed. In this case, small trouble results in significant
trouble that ruins all the wafers.
SUMMARY OF THE INVENTION
[0025] The object of the present invention is to solve the above
problems. More specifically, according to the present invention,
the procedures being carried out sequentially in a device are not
interrupted, and the operation rate does not rapidly drop. Instead,
each module performs an operation independently of other modules.
If there is some trouble caused in one module, the other modules
keep operating. In this manner, the entire operation rate does not
rapidly drop, and a stable operation rate is kept. Also, wafer
transporting devices for connecting modules for the respective
procedures are not required, and an increase in device size due to
the transporting devices can be prevented.
[0026] Also, according to the present invention, the atmosphere in
the electrolytic processing procedure does not adversely affect the
atmosphere in the later washing procedure, or particles are not
scattered about. The adverse influence of the atmosphere in the
electrolytic processing procedure is the problem normally expected
from a combination of the electrolytic processing procedure and the
washing and drying procedures by a conventional technique. The
present invention also eliminates the adverse influence of the
contamination caused by the Cu material that is dissolved by an
electrolytic solution and adheres back to the surface. By doing so,
the electrolytic solution having been used for electrolytic
processing cannot be brought into the next electrolytic processing
procedure and the next washing procedure.
[0027] In a case where each wafer is transported to more than one
module for more than one procedure, all the wafers being
transported in the device are temporarily stopped every time a
maintenance operation is performed, and the operation rate of the
device becomes lower. The present invention is to solve those
technical problems.
[0028] The present invention has been made to solve the above
problems, and according to a first aspect of the present invention,
there is provided an electrolytic processing unit device including:
an electrolytic processor that performs electrolytic processing on
a wafer; a washer that washes the processed wafer; and a drier that
dries the processed or washed wafer, the electrolytic processor,
the washer, and the drier being placed in a processing chamber to
form one module that performs the electrolytic processing, washing,
and drying for the wafer.
[0029] In this structure, the electrolytic processing unit device
has the electrolytic processor, the washer, and the drier placed in
one processing chamber to form one module. Accordingly, the wafer
electrolytic processing, washing, and drying can be continuously
performed in one place. Also, even if some trouble is caused in one
module, the trouble does not affect other modules at all, and it is
not necessary to stop the wafer processing procedures in other
modules.
[0030] According to a second aspect of the present invention, there
is provided the electrolytic processing unit device according to
the first aspect, wherein the electrolytic processor, the washer,
and the drier are aligned on a circular arc or a straight line.
[0031] In this structure, the electrolytic processor, the washer,
and the drier of the electrolytic processing unit device are
arranged along a circular arc or a straight line. Accordingly, when
a wafer is transported to the electrolytic processor, the washer,
and the drier, only one robot that can move along the circular arc
or the straight line is required for the wafer transportation.
[0032] According to a third aspect of the present invention, there
is provided the electrolytic processing unit device according to
the first or second aspect, wherein the electrolytic processor, the
washer, and the drier form one module, and are connected to each
other by one transportation system.
[0033] In this structure, the electrolytic processor, the washer,
and the drier of one module are connected by one transportation
system. Accordingly, only one device is required for transporting
wafers to the electrolytic processor, the washer, and the drier.
Thus, each wafer can be transported to the electrolytic processor,
the washer, and the drier in a sequential manner.
[0034] According to a fourth aspect of the present invention, there
is provided the electrolytic processing unit device according to
any of the first to third aspects, wherein the electrolytic
processor, the washer, and the drier that carry out the above
series of procedures are controlled, operated, and subjected to
maintenance independently of one another.
[0035] In this structure, the electrolytic processor, the washer,
and the drier can be operated, controlled, and subjected to
maintenance independently of one another. Accordingly, when one of
the electrolytic processor, the washer, and the drier is operated,
controlled, and subjected to maintenance, the other procedures do
not need to be stopped.
[0036] According to a fifth aspect of the present invention, there
is provided the electrolytic processing unit device according to
the first or second aspect, wherein a beveling unit for beveling an
outer peripheral portion of the wafer after the electrolytic
processing is provided in the vicinity of the electrolytic
processor.
[0037] In this structure, when the conductive film on the surface
of the wafer is removed from the center toward the outer peripheral
portion of a wafer, a ring-like portion of the conductive film
remains at the outer peripheral portion of the wafer. However, the
ring-like conductive film is beveled by etching or mechanical
processing performed by a beveling unit provided in the vicinity of
the electrolytic processor. Accordingly, each wafer subjected to
electrolytic processing is not moved away from the electrolytic
processor, and is then subjected to beveling.
[0038] According to a sixth aspect of the present invention, there
is provided the electrolytic processing unit device according to
any of the first, third and fourth aspects, wherein the module
includes: an access area through which wafers are brought in and
out; an electrolytic processing head for electrolytic processing
that is provided in a different area from the access area, and a
holding arm that holds the electrolytic processing head; and a
washing arm that supports a wafer washing unit is provided in the
opposite position from the holding arm.
[0039] In this structure, a washing arm supporting a wafer washing
unit is provided in the opposite position from the holding arm that
holds the electrolytic processing head. Accordingly, washing of
each wafer is performed at a spot separated from the spot for
electrolytic processing.
[0040] According to a seventh aspect of the present invention,
there is provided the electrolytic processing unit device according
to the sixth aspect, wherein the wafer washing unit in the module
includes a washing brush, a ultrasonic water supplier, and a
nitrogen blower.
[0041] In this structure, the wafer washing unit includes a washing
brush, a ultrasonic water supplier, and a nitrogen blower.
Accordingly, the electrolytic solution remaining on the surface of
the wafer is removed by washing with the brush and ultrasonic
washing, and the space surrounding the wafer cannot become an
oxygen atmosphere at the time of washing.
[0042] According to an eight aspect of the present invention, there
is provided an electrolytic processing unit device including: an
electrolytic processor that performs electrolytic processing on a
wafer; a washer that washes the processed wafer; and a drier that
dries the processed or washed wafer, the electrolytic processor,
the washer, and the drier being placed in a processing chamber to
form one module that performs the electrolytic processing, washing,
and drying for the wafer, an electrode portion for the electrolytic
processing being made of an inorganic material.
[0043] This structure has the same effects as the first aspect of
the invention, and the electrode portion for electrolytic
processing is made of an inorganic material. Unlike a case with an
electrode portion made of an organic material, the old electrolytic
solution used for electrode processing can be easily rinsed off
from the electrode portion, and the old electrolytic solution
cannot remain at the electrode portion.
[0044] According to a ninth aspect of the present invention, there
is provided a method for electrolytic processing, washing, and
drying in a structure having a wafer chuck mechanism, including the
steps of: performing electrolytic processing by applying a voltage
between an electrode having edges clamped around a wafer and an
electrolytic processing head that scans the surface of the wafer,
after securing the wafer; polishing a conductive film at an edge
portion in the same position, if necessary, while a bottom face of
the wafer is being sucked and fixed after an edge clamp is removed;
scanning the surface of the wafer with a washing arm in the same
position, a washing unit being attached to the washing arm; washing
the processed wafer; and drying the processed or washed wafer in
the same position.
[0045] By this method, the series of procedures of electrolytic
processing, edge processing, washing, and drying for wafers can be
carried out in the same place. Accordingly, wafers do not need to
be moved for each procedure.
[0046] According to a tenth aspect of the present invention, there
is provided the method according to the ninth aspect, wherein the
surface of the wafer and an electrode portion are rinsed with pure
water, after the electrolytic processing procedure and the washing
procedure.
[0047] By this method, the surface of each wafer and the electrode
portion are rinsed with pure water after electrolytic processing
and washing. Accordingly, the electrolytic solution and chemical
solution (washing solution) remaining on the surface of the wafer
can be removed after the electrolytic processing and washing of the
wafer.
[0048] According to the first aspect of the invention, electrolytic
processing, washing, and drying for each wafer can be performed in
one place. With this arrangement, a large space is not required,
and each wafer does not need to be transported through more than
one module as in the prior art. Accordingly, the mechanism such as
a wafer transporting device can be omitted. Also, even if some
trouble is caused in one module, the wafers being transported
through the process line do not need to be stopped by interrupting
the operation of the transportation systems of other modules. Thus,
oxidation degradation and corrosion due to the interruption are not
caused in wafers, and it is unnecessary to create a complicated
program.
[0049] According to the second aspect of the invention, each wafer
can be transported to the electrolytic processor, the washer, and
the drier by one robot. With this structure, the same effects as
those of the first aspect of the invention can be achieved, and the
wafer transporting mechanism can be made simpler than a
conventional one. Also, the electrolytic processor, the washer, and
the drier can be arranged along a circuit arc or a straight line,
in accordance with the situation and objective. Thus, a higher
degree of freedom is allowed in the arrangement of the electrolytic
processor, the washer, and the drier.
[0050] According to the third aspect of the invention, only one
device is required for transporting wafers to the electrolytic
processor, the washer, and the drier. With this structure, the same
effects as those of the first or second aspect of the invention can
be achieved, and the costs for the wafer transportation can be
reduced. Also, the operation rate of the wafer transportation
system can be made higher.
[0051] According to the fourth aspect of the invention, even when
one of the electrolytic processor, the washer, and the drier is
being operated, controlled, or subjected to maintenance, the
operations and the likes in other procedures are not interrupted
and can be continued. With this structure, the same effects as
those of any of the first to third aspects of the invention can be
achieved, and the operating rates of the electrolytic processor,
the washer, and the drier can be made higher than in conventional
cases.
[0052] According to the fifth aspect of the invention, the
conductive film remaining at the outer peripheral portion of each
wafer after electrolytic processing can be subjected to beveling
performed by the beveling unit provided in the vicinity of the
electrolytic processor. With this structure, the beveling can be
performed immediately after the electrolytic processing. Thus, the
same effects as those of the first or second aspect of the
invention can be achieved, and higher efficiency can be expected in
the beveling process.
[0053] According to the sixth aspect of the invention, the washing
of each wafer can be performed at a spot separated from the spot
for electrolytic processing. With this structure, the same effects
as those of any one of the first, third, and fourth aspects of the
invention can be achieved, and the electrolytic solution used for
electrolytic processing cannot be brought into the washer.
[0054] According to the seventh aspect of the invention, the
electrolytic solution remaining on each wafer can be removed by
washing with the brush and ultrasonic washing, and the space
surrounding each wafer cannot become an oxygen atmosphere during
the washing. With this structure, the same effects as those of the
sixth aspect of the invention can be achieved, and the
effectiveness of washing each wafer can be increased. Thus, adverse
influence of an oxygen atmosphere on each wafer can be eliminated
in advance.
[0055] According to the eighth aspect of the invention, the same
effects as those of the first aspect of the invention can be
achieved. More specifically, the mechanism for wafer transportation
can be omitted, and oxidation degradation and corrosion of wafers
can be prevented. Also, it becomes unnecessary to create a
complicated program. In addition to those effects, the old
electrolytic solution used for electrode processing does not remain
at the electrode portion. Accordingly, when electrode processing is
performed with a new electrolytic solution, the old electrolytic
solution does not react with the new electrolytic solution, and
does not adversely affect the electrolytic processing.
[0056] The tenth aspect of the present invention provides the
method for electrolytic processing, washing, and drying according
to the ninth aspect, characterized in that the surface of each
wafer and the electrode portion are rinsed with pure water after
the electrolytic processing procedure and the washing
procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is a plan view showing an exemplary structure of an
electrolytic processing unit device in accordance with an
embodiment of the present invention;
[0058] FIG. 2 is a cross-sectional view showing the electrolytic
processor of the electrolytic processing unit device of FIG. 1;
[0059] FIG. 3 is a schematic perspective view illustrating a state
formed by processing of the electrolytic processing unit device of
the embodiment;
[0060] FIG. 4 is a flowchart showing an example of processing
procedures to be carried out by the electrolytic processing unit
device of this embodiment;
[0061] FIG. 5 is a plan view showing an example arrangement of an
electrolytic processing unit device of the present invention;
[0062] FIG. 6 is a plan view showing another example arrangement of
an electrolytic processing unit device of the present invention;
and
[0063] FIG. 7 is a plan view showing yet another example
arrangement of an electrolytic processing unit device of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0064] To combine the wafer electrolytic processing procedure, the
washing procedure, and the drying procedure into one module, to
prevent each wafer from stopping in other modules even if some
trouble is caused in one of the procedures, and to make a
complicated program unnecessary, the present invention provides an
electrolytic processing unit device that includes an electrolytic
processor for performing electrolytic processing on a wafer, a
washer for washing the processed wafer, and a drier for drying the
processed or washed wafer, and performs the electrolytic
processing, the washing, and the drying of the wafer in one module
that is realized by placing the electrolytic processor, the washer,
and the drier in one processing chamber.
Embodiment
[0065] The following is a description of a suitable embodiment of
the present invention, with reference to FIGS. 1 through 7. This
embodiment is applied to an electrolytic processing unit device
that performs electrolytic processing, washing, and drying of a
wafer formed with conductive films. FIG. 1 is a plan view showing
an exemplary structure of the electrolytic processing unit device
in accordance with this embodiment. FIG. 2 is a cross-sectional
view showing the electrolytic processor of the electrolytic
processing unit device of FIG. 1. FIG. 3 is a schematic perspective
view illustrating a state formed by processing of the electrolytic
processing unit device. FIG. 4 is a flowchart showing an example of
processing procedures to be carried out by the electrolytic
processing unit device. FIGS. 5 through 7 are plan views each
showing an example of arrangement of an electrolytic processing
unit device of the present invention.
[0066] As shown in FIG. 1, the electrolytic processing unit device
1 includes an electrolytic processor 2 that performs electrolytic
processing on a wafer W, a washer 3 that washes the processed wafer
W, and a drier 4 that dries the processed or washed wafer W. The
electrolytic processor 2, the washer 3, and the drier 4 are placed
in a processing chamber (a cleaning room) 5, and the wafer W is
transported to the processing chamber 5 by a transfer robot 6. With
this arrangement, the series of procedures of electrolytic
processing, washing, and drying of the wafer W can be carried out
in the processing chamber 5. The modules for processing procedures
that have been three or more in number by a conventional technique
are integrated into one.
[0067] In this electrolytic processing unit device 1, electrolytic
processing, washing, and drying of the wafer W are carried out in
predetermined order by the electrolytic processor 2, the washer 3,
and the drier 4.
[0068] In the electrolytic processor 2, a carbon electrode is
attached to the top end of the arm. This carbon electrode may have
a brush-like form or a felt-like form. Alternatively, the carbon
electrode may be in a thin, tile-like form. If the carbon electrode
is brought into direct contact with the wafer, the wafer is
damaged. Therefore, the carbon electrode is processed in a
semi-contact state via a thin electrolyte film. Here, electrolytic
dissolution processing is mainly performed. Instead of a carbon
electrode, a wire rod made of a metal material may be used.
[0069] In any case, the electrode should not be made of a material
containing an electrolytic solution, like a polymeric polishing
pad. A polishing pad used in chemical mechanical polishing is made
of foamed polyurethane, which contains a polishing agent. When a
polishing material is processed with an electrolytic solution, the
old electrolytic solution contained in the polishing pad might
exude and react with the new electrolytic solution.
[0070] Therefore, it is necessary to use an inorganic material that
does not contain a used electrolytic solution and is not an organic
material. With an inorganic material, even if an electrolytic
solution containing abrasive grains is used for example, the
electrode portion is rinsed in advance. In this manner, the
electrolytic solution can be easily rinsed off, and, as a washing
atmosphere, does not adversely affect the next washing process.
[0071] After the electrolytic processing, pure water is supplied to
the surface of the wafer W from a pure water nozzle (not shown)
directed to the surface of the wafer W, and the entire surface of
the wafer W is thoroughly rinsed. Through this rinsing process, the
electrolytic solution remaining on the surface of the wafer W is
replaced with pure water. Also, a shower nozzle for supplying pure
water to be used for washing is provided within a cup (not shown)
surrounding the wafer W. This shower nozzle is designed to
thoroughly rinse off the electrolytic solution scattering from the
wafer W inside the cup.
[0072] The electrode used for the electrolytic processing and
provided at the top end of the arm is removed from the position for
processing the wafer W. A pot filled with pure water is prepared in
a stand-by position at a distance from the wafer processing
position. The electrode material is immersed in the pure water in
the pot, so that the electrolytic solution remaining on the
electrode is washed off. Pure water is constantly supplied into the
pot, so that the pot is always in an overflowing state. Even if the
electrode material is a carbon brush or the like, the electrolytic
solution remaining between the bristles of the brush due to a
capillary absorption phenomenon is thoroughly rinsed off by
ultrasonic waves.
[0073] In the above described structure, the mechanism for rinsing
the surface of the wafer W and the electrode material is provided
so as not to leave the electrolytic solution in the later washing
procedure after the electrolytic processing. With this structure,
the electrolytic processing state is not continued into the next
washing procedure, and washing can be performed in a clean
environment.
[0074] The electrolytic processor 2 performs primary processing and
secondary processing so as to remove a conductive film from the
surface of the wafer W. Also, a beveling unit 7 is provided in the
electrolytic processor 2, and the beveling unit 7 performs beveling
on the edge portions remaining on the outer peripheral portion of
the wafer W after the removal. Further, an application mechanism
(not shown) for applying an antioxidant solution to the wafer W
after the secondary processing is completed is provided in the
electrolytic processor 2.
[0075] FIGS. 2 and 3 show a specific example of the electrolytic
processor 2. Reference numeral 8 indicates a wafer holding table
that has the wafer W placed and fixed thereon, and can be
rotatively driven. A fixing unit 9 for placing and fixing the wafer
W is provided at the upper face portion of the wafer holding table
8. In the example shown in the drawings, a vacuum chuck unit is
provided.
[0076] Further, a processing head 10 is provided above the wafer
holding table 8. As shown in FIG. 3, a processing electrode 11 is
provided at the top end of the processing head 10, so as to face
the upper face of the wafer W, with a very small space being left
between the processing electrode 11 and the upper face of the wafer
W. The processing head 10 is attached to a movable member 12 such
as an arm or a slider provided in the vicinity of a side of the
wafer holding table 8. In the example shown in the drawings, the
processing head 10 is attached to the top end of the double-arm
movable member 12, and the base portion of the movable member 12 is
linked to the upper portion of a vertical axis 13 having an
adjustable height. The base portion of the movable member 12 is
connected to the upper portion of the vertical axis in a
horizontally rotatable fashion. Accordingly, the processing head 10
is horizontally rotated from the center of the wafer W toward the
outer peripheral portion, so that the processing electrode 11 moves
outward in the radial direction of the wafer W.
[0077] At the outer peripheral portion of the wafer W, there are
six detachable wafer chucks 21 through 26 that rotate integrally
with the wafer holding table 8. These wafer chucks 21 through 26
are arranged at regular intervals in the outer circumferential
direction of the wafer W. Also, the wafer chucks 21 through 26 can
move back and forth, and are adjustable up and down with respect to
the outer peripheral portion of the wafer W on the wafer holding
table 8. Further, supply electrodes A through F for supplying power
to the wafer W are provided inside the respective wafer chucks 21
through 26. Each of the supply electrodes A through F is sealed and
protected, so as to prevent liquid and the likes from entering the
supply electrodes A through F. A tester (not shown) for measuring
the mutual electric resistance is interposed between each two of
the supply electrodes A through F. Alternatively, one tester may be
provided to check the resistance between each two of the supply
electrodes A through F by switching the electrodes.
[0078] A voltage is applied between the processing electrode 11 and
the supply electrodes A through F by a DC low-voltage supply 15,
and an electrolytic solution (a slurry) 17 is supplied onto the
upper face of the wafer W by a supply nozzle 16. The electrolytic
solution 17 may suitably be phosphoric acid, sodium nitride,
ammonium chloride, sulfuric acid, hydrochloric acid, or a mixed
solution of them.
[0079] The electrode portion is made of carbon or the like. If a
hydroplane state is formed with the water film of the electrolytic
solution 17 when an electrode is brought close to the wafer W, the
interelectrode space can be made very small, and the convex portion
on the wafer W is electrolytically concentrated. Thus, only the
convex portion can be selectively processed and removed.
[0080] The electrode portion should desirably have a flat shape
with respect to the surface of the wafer W facing the electrode. If
the electrode becomes large in size, however, the relationship
between the electrode and the surface of the wafer W becomes equal
to a relationship between flat faces, and the electrode might be
partially brought into contact with the surface of the wafer W. If
there is a contact, short-circuiting might be caused, and the wafer
W is damaged by the hard carbon. Therefore, it is preferable that
the electrode area is made so small that there is not a contact
portion in the plane, while the very small space is maintained. The
desirably effective electrode area is approximately +20 mm.
[0081] In a case where only the electrolytic dissolution processing
is performed, a nonconductive film might be formed on the surface,
particularly with Cu, Ta, or the like. In such a case, the current
might rapidly decrease, and the processing might not proceed at a
certain spot. In this case, an electrode in the form of a carbon
brush is suitable as the electrode. With a brush-like shape, the
top end of the electrode is in contact with the surface of the
wafer W. However, when an electrolytic solution is supplied while
the wafer W is rotated, the top end is not completely in contact
with the surface of the wafer W, and a very small space is
maintained between the electrode and the surface of the wafer
W.
[0082] For example, if a carbon brush is formed with brushes each
having a large number of thin bristles of approximately 0.15 mm
tied together, constant pressure is applied onto the surface of the
wafer W from the top end of one brush, though the pressure is very
small as each brush bends. With this pressure, an even smaller
space is formed between the wafer W and the carbon brush electrode.
Due to the space, electrolytic processing can be selectively
performed on the convex portion of the wafer W.
[0083] At the time of electrolytic processing, while the
electrolytic solution 17 is being supplied between the rotating
wafer W and the processing electrode 11, electrolytic polishing is
performed by applying a voltage, so that the conductive film on the
upper face of the wafer W can be evenly removed. In this case, the
processing electrode 11 is gradually scan-moved from the center of
the wafer W toward the outer peripheral portion.
[0084] The processing is completed at the center of the wafer W,
and the processed region is widened toward the outer peripheral
portion. In this manner, uniform processing can be performed on the
entire surface of the wafer W. When scanning is performed with the
movable member (arm) 12 having the processing electrode 11, the
scan speed should be changed in accordance with the processed state
of the wafer W.
[0085] The processed state of the surface of the wafer W can be
monitored by a sensor attached to the scan arm for the electrolytic
processing. The sensor can sense changes in the color of the
surface of the wafer W. In a case where the wafer W is made of Cu,
a clear change in the film color can be observed when the type of
film is switched from a Cu film to a Ta film.
[0086] As the sensor that can sense changes in the color of the
surface, a spectrometer or the like may be used. With a
spectrometer, light is dispersed by a prism or grating, and the
intensity distribution of the dispersed light at each wavelength is
measured with the use of a Linear Image Sensor S3901/S3904 series
(manufactured by Hamamatsu Photonics K. K.). In this manner,
changes in the film color can be detected with high precision.
[0087] After the electrolytic processing, a rinsing procedure is
carried out to remove the electrolytic solution 17 from the surface
of the wafer W. In the rinsing procedure, the surface of the wafer
W is rinsed, and pure water is sprayed to the wafer chucks 21
through 26 and the inside of the process washing cup provided below
them, so as to rinse off the wafer chucks 21 through 26 and the
inside of the process washing cup.
[0088] In the washer 3, the wafer W after the electrolytic
processing is washed with a pen brush. The pen brush is suitably a
sponge made of polyvinyl alcohol (PVA). First, the wafer W is
rotated, and a washing chemical solution or water is supplied to
the portion surrounding the center of the surface of the wafer W.
The wafer W is then scanned with the pen brush, so that the surface
of the wafer W can be cleaned (the primary washing).
[0089] There might be particles remaining on the surface of the
wafer W even after the washing. In such a case, the surface of the
wafer W should be rinsed with pure water. Particularly, when the
wafer W is washed with ultrasonic waves, the particles remaining on
the surface of the wafer W can be completely removed (the secondary
washing).
[0090] The pen brush and the ultrasonic generator are attached to
the top end 20 of a washing movable arm 19 that is horizontally
rotatable about a vertical axis 18. The washing movable arm 19 is
provided in the vicinity of the other side of the wafer holding
table 8. Accordingly, the pen brush and the ultrasonic generator
provided at the top end 20 of the movable arm 19 moves in the
radial direction of the wafer W, as the washing movable arm 19 is
horizontally rotated.
[0091] Also, there are cases where the remnant cannot be removed by
physical washing with the pen brush, depending on the material. To
counter such a situation, a chemical nozzle (not shown) is provided
and is directed toward the wafer W. Particularly, the additive
component and the dissolved metal component of the electrolytic
solution might become a contaminating component and adversely
affect the wafer W.
[0092] To eliminate such a contaminating component of the wafer W,
an acidic chemical solution such as hydrofluoric acid or
hydrochloric acid may be used, or an alkaline chemical solution
such as ammonia may be used. The contamination is removed with such
a chemical solution and the pen brush, and at the same time, the
particles remaining on the surface of the wafer W may be
removed.
[0093] The used chemical solution is also drained off, coming into
contact with the cup surrounding the wafer W. Also, the scattered
chemical solution is constantly rinsed off with a pure water shower
within the cup. Accordingly, when electrolytic processing is
performed again, the chemical solution used for the washing does
not have adverse influence.
[0094] In the procedure for rinsing off the used chemical solution,
pure water washing may be performed with ultrasonic waves. With
ultrasonic waves, the chemical solution remaining on the surface of
the wafer W can be more effectively rinsed off, and the chemical
solution remaining inside the cup can be completely washed
away.
[0095] In the drying procedure to be carried out at last, the
surface of the wafer W is rinsed with pure water. Immediately after
that, spin drying can be performed. The wafer chucks 21 through 26
can revolve, with the maximum number of revolutions being 2000
rpm.
[0096] A polishing head and a polishing platen that are normally
used in electrolytic polishing are very large and heavy, and as a
result, produce a vibration in the entire device when revolving at
a high speed. However, with the light-weight wafer chucks 21
through 26 in accordance with the present invention, washing can be
performed after electrolytic processing, and drying is then
performed by spinning the wafer chucks 21 through 26 at a high
speed, with the maximum number of revolutions being 2000 rpm.
[0097] In a process using a low-k material, the surface of the
wafer W has water repellency, and therefore, a watermark sometimes
appears. In such a case, normal spin drying is not suitable. One of
the reasons for the appearance of a watermark is that water is not
removed as a whole but is divided into droplets of water due to the
water repellency of the surface of the wafer W. It is believed that
those droplets absorb oxygen, and the water containing oxygen
reacts with the low-k material to form a silicon oxide with a
different composition.
[0098] To counter this problem, the entire module for electrolytic
processing and washing and drying is formed in a sealed container
housing that is compact in size. The housing is designed to serve
as a pressure container that can withstand up to 10 Pa.
Particularly, in the last drying procedure, spin drying should be
performed with a pressure increased to approximately 8 Pa in a
nitrogen atmosphere.
[0099] In a nitrogen atmosphere, a silicon oxide that forms
unnecessary watermarks due to the oxygen contained in pure water is
not formed on the surface of the low-k material. Also, with the
increased pressure, the contact angle of the water is increased,
and an environment that is not water repellent in appearance can be
formed. With such an environment, formation of watermarks can be
prevented even when spin drying is performed.
[0100] By another method for preventing formation of watermarks due
to spin drying, alcohol such as IPA may be incorporated into the
pure water to be supplied in the rinsing procedure prior to the
spin drying. The water containing IPA increases the wetness of the
surface of the wafer W, and dramatically increases the contact
angle. As a result, even after normal spin drying is performed,
watermarks are not formed on the surface of the wafer W, and a dry
surface can be maintained.
[0101] In the wafer drier 4, the washed wafer W is subjected to
spin drying. In this case, the wafer chucks 21 through 26 attached
during the electrolytic processing may be detached or may not be
detached from the wafer W. After that, the wafer W is spun around,
so that the electrolytic solution and water remaining on the
surface of the wafer W can be thrown off and eliminated.
[0102] Instead of pure water, an aqueous solution containing
alcohol may be used. With such an aqueous solution, the surface
tension can be reduced, and the spin drying becomes easier.
Particularly, for a low-k material having a water-repellent
surface, such a process is suitable.
[0103] Referring now to FIG. 4, an example of the operation of
processing the wafer W in accordance with this embodiment is
described. First, the wafer W is transported to the processing
chamber 5 by the robot 6, and is placed on the wafer holding table.
The wafer W is then fixed to the wafer holding table by the wafer
chucks 21 through 26. This fixing is performed to bring the power
supply unit into contact with the surface of the wafer W at the
same time as the fixing. Also, the fixing is performed to secure
the wafer W at the center of the wafer holding table. The vacuum
chuck of the wafer holding table forms a vacuum for the secured
wafer W, so as to firmly attach the wafer W onto the wafer holding
table 8.
[0104] While an electrolytic solution is being applied onto the
surface of the wafer W, the processing electrode 11 attached to the
top end of the scan arm is caused to act on the surface of the
wafer W, so that electrolytic processing is performed. In the
electrolytic processor 2, the conductive film (a Cu film or a Ta
film) on the surface of the wafer W is removed by electrolytic
polishing. More specifically, a voltage is applied between the
rotating wafer W and the processing electrode 11 while the
electrolytic solution 17 is being supplied, and the processing
electrode 11 is caused to scan the wafer W from the center toward
the outer periphery of the wafer W. In this manner, the conductive
film on the surface of the wafer W is gradually and evenly removed
from the center toward the outer periphery of the wafer W (step
S1).
[0105] After the conductive film is evenly removed from the center
to the outer periphery of the wafer W, an anticorrosion solution is
applied from the center to the outer periphery of the wafer W. The
ring-like Cu film remaining at the outer periphery of the wafer W
at the end of the electrolytic processing is removed by etching or
mechanical processing in the beveling unit 7 (step S2).
[0106] The wafer W subjected to the electrolytic processing is not
moved and remains in the same position. The wafer W is then washed
by the washer 3 as a different arm from the scan arm for the
electrolytic processing. More specifically, the pen brush is
brought into contact with the surface of the wafer W, and the
surface of the wafer W is washed by jetting a washing solution or
pure water. After that, the surface of the wafer W is rinsed with
pure water having ultrasonic waves applied thereto (steps S3 and
S4).
[0107] The washed wafer W is then subjected to spin drying in the
drier 4. More specifically, the wafer W is spun around on the wafer
holding table 8, so that the electrolytic solution 17 and water
remaining on the surface of the wafer W are thrown off due to the
centrifugal force (step S5).
[0108] As described above, in this embodiment, the electrolytic
processor 2, the washer 3, and the drier 4 are placed in the
processing chamber 5, so as to form one module. Accordingly, not
only the entire device and the space for the device can be made
smaller, but also the electrolytic processing, the washing, and the
drying of the wafer W can be sequentially performed in one place in
a continuous manner.
[0109] To maintain cleanness, a downward air current is supplied to
the module that performs the electrolytic processing, the washing,
and the drying of the wafer W, from the above via a hepafilter.
Accordingly, the wafer W and its surrounding area are constantly in
a clean air current. Thus, after the drying of the wafer W at last,
the wafer W having a clean surface without remnant particles can be
transferred to the transportation robot.
[0110] To counter the problem of watermarks at the time of
electrolytic processing or washing and drying, N.sub.2 blowing may
be performed on the wafer W and its surrounding area in the module.
A N.sub.2 nozzle to introduce liquid nitrogen is placed on the
wafer W, and cooled N.sub.2 is supplied to the wafer W and its
surrounding area. In this manner, the wafer W and its surrounding
area can be separated and isolated from the atmosphere containing
oxygen.
[0111] Since there is no oxygen in the atmosphere, oxidation of the
Cu surface can be prevented during the electrolytic processing, and
formation of watermarks formed by the oxygen that is contained in
the pure water and reacts with the surface of the low-k material
can be prevented during the wafer drying procedure.
[0112] Accordingly, even if some trouble is caused in one of the
electrolytic processor 2, the washer 3, and the drier 4 of the
module, the trouble does not adversely affect the processing
procedures in other modules. Therefore, it is not necessary to
interrupt the processing procedures in other modules, and oxidation
degradation and corrosion due to the interruption are not caused.
Furthermore, it is not necessary to prepare a complicated
program.
[0113] FIGS. 5 and 6 show other examples of the electrolytic
processing unit device 1 in accordance with the present invention.
In these examples, the electrolytic processor 2, the washer 3, and
the drier 4 are arranged in a circular arc or in a straight line in
the processing chamber 5. The wafer W is transported to the
electrolytic processor 2, the washer 3, and the drier 4 by a
double-arm robot 27 that can move in a desired direction (can move
straight and spin around). It is also possible to provide two
robots 27 that are interposed between electrolytic processors 2,
washers 3, and driers 4, as shown in FIG. 7. The two robots 27 are
designed to move independently of each other.
[0114] In any of these structures, electrolytic processing,
washing, and drying of the wafer W can be performed with one
module. Accordingly, even if some trouble is caused in the module,
the processing of other wafers W in other modules is not
interrupted. Furthermore, the mechanism of rotating a polishing pad
that is necessary in a conventional CMP device can be omitted, and
the amount of mechanical processing can be reduced. Thus, the
device mechanism can be simplified and made more lightweight.
[0115] Unlike a conventional structure having more than one module
for each of the procedures of electrolytic processing, washing, and
drying, the device in accordance with the present invention does
not require a mechanism for transporting each wafer W between the
modules. Thus, the mechanism and the processing program can be
further simplified.
[0116] In the above described embodiment, the number of
electrolytic processors, the number of washers, and the number of
driers in one electrolytic processing unit device are one. However,
it is possible to employ two or more electrolytic processors, two
or more washers, and two or more driers, if necessary.
[0117] As described above, in the present invention, the
electrolytic processor, the washer, and the drier that form one
module are connected by one transportation system. Accordingly,
only one device for transporting the wafer W to the electrolytic
processor, the washer, and the drier is required. With the one
device for transportation, the wafer W can be continuously
transported to the electrolytic processor, the washer, and the
drier. Thus, the costs for the wafer transportation system can be
reduced, and the operation rate of the wafer transporting device
can be made higher.
[0118] Furthermore, the electrolytic processor, the washer, and the
drier can be operated, controlled, and subjected to maintenance
independently of one another. Accordingly, when one of the
electrolytic processor, the washer, and the drier is operated,
controlled, or subjected to maintenance, the operations at the
other components do not need to be stopped. Thus, the operating
rates of the electrolytic processor, the washer, and the drier can
be made higher.
[0119] Further, the washing arm supporting the wafer washing unit
is provided to face the arm that holds the electrolytic processing
head, so that the wafer W is washed at a spot separated from the
spot for the electrolytic processing. Thus, the electrolytic
solution used for the electrolytic processing cannot be brought
into the washer.
[0120] Since the wafer washing unit includes a washing brush, a
ultrasonic water supplier, and a nitrogen blower, the electrolytic
solution remaining on the surface of the wafer W can be removed by
brush washing and ultrasonic washing, and the space surrounding the
wafer W cannot become an oxygen atmosphere during the washing.
Thus, the effectiveness of washing the wafer W is increased, and
the wafer W is not adversely affected by an oxygen atmosphere.
[0121] Since the electrode portion is made of an inorganic
material, the old electrolytic solution used for electrode
processing cannot remain at the electrode portion. Accordingly,
when electrolytic processing is performed with a new electrolytic
solution, a reaction between the new electrolytic solution and the
old electrolytic solution can be prevented.
[0122] Furthermore, the series of procedures of electrolytic
processing, edge processing, washing, and drying for the wafer W
are carried out in the same position. Accordingly, the wafer W does
not need to be moved for each procedure, and the series of
procedures can be carried out in a continuous manner.
[0123] In this embodiment, the surface of the wafer W and the
electrode portion are rinsed with pure water after electrolytic
processing and washing. Through the rinsing, the electrolytic
solution and chemical solution remaining on the surface of the
wafer W at the time of electrolytic processing and washing can be
thoroughly removed. In this manner, degradation of the processing
quality of the wafer W due to the electrolytic solution and
chemical solution can be effectively prevented.
[0124] It should be understood that various changes and
modifications may be made to the above embodiments, without
departing from the scope of the invention, and the present
invention is applicable to the changes and modifications.
* * * * *