U.S. patent application number 14/673611 was filed with the patent office on 2015-10-29 for anodizing apparatus.
The applicant listed for this patent is Solexel, Inc.. Invention is credited to Noriyuki HAYASHI, Takamitsu INAHARA, Karl-Josef KRAMER, Yasuyoshi MIYAJI, Subramanian TAMILMANI, Takao YONEHARA.
Application Number | 20150308008 14/673611 |
Document ID | / |
Family ID | 46161193 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150308008 |
Kind Code |
A1 |
MIYAJI; Yasuyoshi ; et
al. |
October 29, 2015 |
ANODIZING APPARATUS
Abstract
An apparatus for anodizing substrates immersed in an electrolyte
solution. A substrate holder mounted in a storage tank includes a
first support unit having first support elements for supporting, in
a liquid-tight condition, portions of the substrates, and a second
support unit attachable to and detachable from the first support
unit and having second support elements for supporting, in a
liquid-tight condition, the remaining portions of the substrates.
The second support unit includes a first portion second support
unit having support elements for supporting first portions of the
remaining portions of the surfaces of the substrates, and a second
portion second support unit having support elements for supporting
second portions of the remaining portions of the surfaces of the
substrates.
Inventors: |
MIYAJI; Yasuyoshi; (Kyoto,
JP) ; HAYASHI; Noriyuki; (Kyoto, JP) ;
INAHARA; Takamitsu; (Kyoto, JP) ; YONEHARA;
Takao; (Sunnyvale, CA) ; KRAMER; Karl-Josef;
(San Jose, CA) ; TAMILMANI; Subramanian;
(Milpitas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Solexel, Inc. |
Milpitas |
CA |
US |
|
|
Family ID: |
46161193 |
Appl. No.: |
14/673611 |
Filed: |
March 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13310083 |
Dec 2, 2011 |
8992746 |
|
|
14673611 |
|
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Current U.S.
Class: |
204/252 ;
204/242 |
Current CPC
Class: |
C25D 11/005 20130101;
C25D 17/005 20130101; C25D 17/02 20130101; C25D 17/002 20130101;
Y10S 414/136 20130101; Y10S 414/139 20130101; Y10S 414/141
20130101; Y10S 414/135 20130101; Y10S 414/138 20130101; Y10S
414/137 20130101; Y10S 414/14 20130101 |
International
Class: |
C25D 11/00 20060101
C25D011/00; C25D 17/02 20060101 C25D017/02; C25D 17/00 20060101
C25D017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 2, 2010 |
JP |
2010-269416 |
Dec 2, 2010 |
JP |
2010-269417 |
Claims
1. An anodizing apparatus for causing an anodizing reaction on
substrates immersed in an electrolyte solution, comprising: a
storage tank storing the electrolyte solution; a substrate holder
mounted in the storage tank, and including a first support unit
having a plurality of first support elements arranged in a
direction of arrangement of the substrates for contacting and
supporting, in a liquid-tight condition, portions of surfaces of
the substrates, and a second support unit attachable to and
detachable from the first support unit and having a plurality of
second support elements arranged in the direction of arrangement of
the substrates for contacting, in a liquid-tight condition,
remaining portions of the surfaces of the substrates other than the
portions supported by the first support elements; and wherein the
second support unit includes a first portion second support unit
having support elements for supporting first portions of the
remaining portions of the surfaces of the substrates, and a second
portion second support unit having support elements for supporting
second portions of the remaining portions of the surfaces of the
substrates.
2. The apparatus according to claim 1, wherein said first and
second support units are constructed for contacting and supporting
said surfaces of said substrates, in said liquid-tight condition,
wherein said surfaces are circular.
3. The apparatus according to claim 1, wherein said first and
second support units are constructed for contacting and supporting
said surfaces of said substrates, in said liquid-tight condition,
wherein said surfaces are square.
4. The apparatus according to claim 1, wherein the substrate holder
assumes a cylindrical appearance when the first support unit and
the second support unit are connected, and includes ion-exchange
membranes disposed at one end and the other end thereof in the
direction of arrangement of the substrates for permitting passage
of ions and blocking passage of part of the electrolyte solution in
the substrate holder and part of the electrolyte solution in the
storage tank.
5. The apparatus according to claim 1, wherein the first support
elements support lower portions of the surfaces which correspond to
chords shorter than diameters of the substrates.
6. The apparatus according to claim 1, wherein the second support
elements have exhaust passages extending from inner surfaces to
outer surfaces thereof, with upper openings thereof located above a
solution level in the storage tank.
7. The apparatus according to claim 1, wherein the first support
elements have an elastic member applied to inner surfaces thereof,
and grooves formed in positions where lower surfaces of the
substrates are placed.
8. The apparatus according to claim 1, wherein the first support
elements have guide pins arranged at opposite sides of each groove
for guiding the substrates being placed and preventing turnover of
the substrates.
9. The apparatus according to claim 1, wherein each of the guide
pins has a base projecting from the elastic member, and a guide
portion formed on an upper part of the base and projecting from the
base toward one of the substrates.
10. The apparatus according to claim 1, wherein a junction between
the first portion second support unit and the second portion second
support unit has a notch pressing mechanism for pressing notches of
the substrates through elastic members provided on inner surfaces
of the first portion second support unit and the second portion
second support unit.
11. The apparatus according to claim 10, wherein the notch pressing
mechanism includes a slide member provided on one of the first
portion second support unit and the second portion second support
unit to be slidable toward centers of the substrates, and a
pressing member provided on the other of the first portion second
support unit and the second portion second support unit for
pressing the slide member when the first portion second support
unit and the second portion second support unit join each
other.
12. The apparatus according to claim 6, wherein an elastic member
provided on inner surfaces of the first support elements is harder
than an elastic member provided on inner surfaces of the second
support elements.
13. The apparatus according to claim 1 further comprising foamed
materials provided for a junction between the first portion second
support unit and the first support unit, and for a junction between
the second portion second support unit and the first support unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/310,083 filed Dec. 2, 2011 which claims benefit of Japanese
International Application Nos. JP 2010-269417 filed Dec. 2, 2010
and JP 2010-269416 filed Dec. 2, 2010, all of which are hereby
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an anodizing apparatus for
carrying out electrolytic etching treatment on various substrates,
such as semiconductor wafers, substrates for liquid crystal
displays, substrates for plasma displays, substrates for organic EL
devices, substrates for FEDs (Field Emission Displays), optical
disk substrates, substrates for magnetic disks, substrates for
magnetic optical disks, substrates for photomasks, substrates for
solar cells, and substrates for micro-electro-mechanical systems
(MEMS). More particularly, the invention relates to a batch
processing technique for treating a plurality of substrates at the
same time with high throughput.
[0004] 2. (2) Description of the Related Art
[0005] Conventionally, an apparatus (first apparatus) of this type
includes a fluororesin forming tank (2), a pair of platinum
electrodes (3a, 3b), and a substrate support jig (4) for holding a
substrate (1) (see Japanese Unexamined Patent Publication H5-198556
(FIGS. 1 and 2), for example).
[0006] The fluororesin forming tank (2) stores an electrolytic
solution (6a, 6b). The pair of platinum electrodes (3a, 3b) are
arranged, as spaced from each other, inside the fluororesin forming
tank (2). The substrate support jig (4) has an opening
substantially corresponding to the outside diameter of the
substrate (1), and has a cutout spreadable for inserting the
substrate (1) into the substrate support jig (4). The jig (4) holds
the substrate (1) through a seal (5a) to be liquid-tight with
respect to the electrolytic solution (6a, 6b). The substrate
support jig (4) is immersed along with the substrate (1) in the
electrolytic solution (6a, 6b) in the fluororesin forming tank (2).
When the pair of platinum electrodes (3a, 3b) are electrified, a
chemical reaction starts to render the substrate (1) porous through
the opening.
[0007] Another apparatus (second apparatus) of this type includes
an electrolytic solution tank (11), a pair of electrodes (14A,
14B), and a substrate support member (15) for holding a substrate
(S) (see Japanese Unexamined Patent Publication No. 2003-45869
(FIGS. 1 and 3), for example).
[0008] The electrolytic solution tank (11) stores an electrolytic
solution. The pair of electrodes (14A, 14B) are attached to
opposite inner walls of the electrolytic solution tank (11). The
substrate support member (15) has a first cassette (21) and a
second cassette (22) for pinching the substrate (S) in between. The
first cassette (21) has an opening (21A) substantially
corresponding to the diameter of the substrate (S), and the second
cassette (22) has a similar opening (22A). The first cassette (21)
and second cassette (22) of the substrate support member (15) hold
the substrate (S) in between, and engage the substrate (S) by
pressing on peripheries of the substrate (S). The substrate support
member (15) is inserted in a guide groove (16) of the electrolytic
solution tank (11), the pair of electrodes (14A, 14B) are
electrified, thereby causing a chemical reaction to render the
substrate (S) porous through the openings (21A, 22A).
[0009] A further apparatus (third apparatus) of this type includes
a lower tank portion (103), an upper tank portion (104), an anode
plate (101), a silicon wafer (106), and a cathode plate (102) (see
Japanese Unexamined Patent Publication H6-275598 (FIG. 1), for
example).
[0010] The lower tank portion (103) and upper tank portion (104)
store an electrolytic solution, and a wafer (105) under treatment
is placed therebetween. The silicon wafer (106) is disposed to
contact the anode plate (101) electrically, and not to contact the
electrolytic solution in the lower tank portion (103). When the
anode plate (101) and cathode plate (102) are electrified, a
chemical reaction takes place to render the wafer (105) porous.
[0011] Since, in the third apparatus, the silicon wafer (106) keeps
the anode plate (101) out of contact with the electrolytic
solution, the metal of the electrode (101) does not elute in the
electrolytic solution. This prevents metal contamination of the
wafer (105).
[0012] However, the conventional examples with such constructions
have the following problems.
[0013] In the first conventional apparatus, in order to make the
substrate support jig (4) support the substrate (1), it is
necessary to insert the substrate (1) in the opening after
spreading the cutout of the substrate support jig (4). It is
therefore difficult to make the substrate support jig (4) support
the substrate (1) automatically by means of a mechanical device.
When the apparatus is applied to batch processing for treating a
plurality of substrates (1) at the same time, it becomes more
difficult to automate the treatment in an effective way.
[0014] In the second conventional apparatus, in order to make the
substrate support member (15) hold the substrate (S), it is
necessary to place the substrate (S) to be pinched between the
first cassette (21) and second cassette (22). Therefore, as with
the first apparatus, there is a problem of being incapable of
automating the treating process. Although the publication discloses
an embodiment for treating two substrates (S), since the substrate
support member (15) is constructed to have a considerable
thickness, the apparatus is unsuitable for batch processing for
treating an increased number of substrates (S).
[0015] The third conventional apparatus has the same problem as the
first apparatus. In addition, since the silicon wafer (106) is made
porous by the chemical reaction, it will be necessary to change the
silicon wafer (106) frequently. Therefore, this apparatus has an
additional problem of consuming time in maintenance to lower its
operating rate.
SUMMARY OF THE INVENTION
[0016] This invention has been made having regard to the state of
the art noted above, and its object is to provide an anodizing
apparatus well suited for automation and batch processing, which is
achieved by devising a mechanism for holding substrates.
[0017] Another object of this invention is to provide an anodizing
apparatus which is capable of batch processing and of holding down
the frequency of changing electrodes to improve the operating
rate.
[0018] The above object is fulfilled, according to this invention,
by an anodizing apparatus for causing an anodizing reaction on
substrates immersed in an electrolyte solution, comprising a
storage tank for storing the electrolyte solution. A substrate
holder is mounted in the storage tank, and including a first
support unit having a plurality of first support elements arranged
in a direction of arrangement of the substrates for contacting and
supporting, in a liquid-tight condition, portions of surfaces of
the substrates, and a second support unit attachable to and
detachable from the first support unit and having a plurality of
second support elements arranged in the direction of arrangement of
the substrates for contacting and supporting, in a liquid-tight
condition, remaining portions of the surfaces of the substrates
other than the portions supported by the first support elements.
The second support unit includes a first portion second support
unit having support elements for supporting first portions of the
remaining portions of the surfaces of the substrates, and a second
portion second support unit having support elements for supporting
second portions of the remaining portions of the surfaces of the
substrates.
[0019] According to one aspect of the disclosed subject matter, a
drive mechanism may be utilized for separating the first support
unit and the second support unit when placing the plurality of
substrates in the substrate holder and when unloading the plurality
of substrates from the substrate holder, and for connecting the
first support unit and the second support unit after the plurality
of substrates are placed in the substrate holder.
[0020] According to this invention, the drive mechanism may
separate the first support unit and second support unit of the
substrate holder arranged in the storage tank. In this state, a
plurality of substrates are respectively placed between the first
support elements of the first support unit, whereby only lower
portions of the circumferential surfaces of the substrates are
supported in a liquid-tight condition relative to the electrolyte
solution. When the second support unit is connected to the first
support unit by the drive mechanism, the plurality of substrates
are supported by the second support elements, with the remaining
portions of the circumferential surfaces of the substrates put in a
liquid-tight condition relative to the electrolyte solution.
Consequently, the entire circumferential surfaces of the substrates
are now in the liquid-tight condition relative to the electrolyte
solution. After the anodizing reaction is completed, the second
support unit is separated from the first support unit by the drive
mechanism, and the plurality of substrates supported by the first
support unit are unloaded therefrom. Thus, the first support unit
and second support unit of the substrate holder being attachable to
and detachable from each other by the drive mechanism enables a
plurality of substrates to be mechanically loaded into and unloaded
from the storage tank. As a result, the anodizing apparatus
provided is well suited for automation and batch treatment.
[0021] In this invention, the substrate holder may assume a
cylindrical appearance when the first support unit and the second
support unit are connected, and include ion-exchange membranes
disposed at one end and the other end thereof in the direction of
arrangement of the substrates for permitting passage of ions and
blocking passage of part of the electrolyte solution in the
substrate holder and part of the electrolyte solution in the
storage tank.
[0022] When the first support unit and second support unit of the
substrate holder are connected, the electrolyte solution in the
storage tank and the electrolyte solution in the substrate holder
are separate from each other. This assures a constant concentration
of the electrolyte solution around the substrates during the
anodizing reaction. Therefore, the plurality of substrates treated
at the same time can undergo a uniform anodizing reaction. When
replacing the plurality of substrates with a new plurality of
substrates, the first support unit and second support unit are
separated from each other. This results in an interchange between
the electrolyte solution in the substrate holder and the
electrolyte solution in the storage tank, whereby the concentration
of the electrolyte solution is made equal for the different lots.
Therefore, the treatment can be uniformed between the lots.
[0023] In this invention, the second support unit may include a
left second support unit having left second support elements as the
second support elements for supporting left sides of the remaining
portions of the circumferential surfaces of the substrates, and a
right second support unit having right second support elements as
the second support elements for supporting right sides of the
remaining portions of the circumferential surfaces of the
substrates.
[0024] Since the second support unit may be divided into a left
second support unit and a right second support unit which, when
separated from the first support unit, can easily open up areas
above the plurality of substrates supported by the first support
unit. This allows a transport mechanism to move easily to and from
the substrate holder for transferring the plurality of
substrates.
[0025] In this invention, the first support elements may support
lower portions of the circumferential surfaces which correspond to
chords shorter than diameters of the substrates.
[0026] This allows the transport mechanism for transferring the
substrates to and from the substrate holder to hold the substrates
at portions below maximum diameter portions thereof. Thus, the
transport mechanism can hold the substrates reliably without
applying stress to the substrates.
[0027] According to one aspect of the disclosed subject matter, a
left second support unit and a right second support unit may have
fulcrums, respectively, located in positions at a bottom of the
storage tank and having the first support unit in between, and may
be rockable away from each other when separating from the first
support unit. The left second support unit and right second support
unit, when rocking about the respective fulcrums to connect to the
first support unit, will apply forces from the circumferential
surfaces of the substrates toward the centers of the substrates.
Thus, the left second support unit and right second support unit
can support the circumferential surfaces of the substrates in a
liquid-tight condition without applying excessive stress to the
substrates. When separated, the left second support unit and right
second support unit will move to positions to have the inner
surfaces thereof turned upward. In such positions, bubbles
generating from the chemical reaction can be released, thereby to
prevent treating unevenness due to the bubbles from occurring to
succeeding lots.
[0028] In this invention, the apparatus may further comprise a pair
of covers for opening and closing an upper opening of the storage
tank, wherein the drive mechanism is used also as a cover drive
mechanism for driving the pair of covers in opening and closing
operations.
[0029] A drive mechanism may also be used as the cover drive
mechanism for driving the pair of covers can simplify the
construction and facilitate control of various components at times
of transporting the substrates. When the covers are closed by the
cover drive mechanism, the substrate holder can support the entire
circumferential surfaces of the substrates in the liquid-tight
condition with increased reliability. When the covers are opened,
the upper portions of the substrate holder are also opened. This
can shorten the time taken in transporting the substrates into and
out of the treating tank while maintaining the uniform treatment of
the substrates.
[0030] In this invention, the second support elements may have
exhaust passages extending from inner surfaces to outer surfaces
thereof, with upper openings thereof located above a solution level
in the storage tank. Gas generated by the anodizing reaction and
stagnating as bubbles in the substrate holder could cause reaction
unevenness. However, the exhaust passages are provided to discharge
the generated gas, instead of allowing the gas to stagnate in the
substrate holder. This construction can prevent the treating
unevenness due to the bubbles.
[0031] In this invention, the first support elements may have an
elastic member applied to inner surfaces thereof, and grooves
formed in positions where lower surfaces of the substrates are
placed. When the substrates are placed on the first support
elements and the upper circumferential surfaces of the substrates
are supported by the second support elements, the lower
circumferential surfaces of the substrates will press the elastic
member and enter the grooves. Therefore, part of the front and rear
surfaces of each substrate including the circumferential surface
thereof can be supported, whereby the electrolyte solution does not
circulate between adjoining substrates. As a result, the
concentration of the electrolyte solution acting on the substrates
remains stable, to realize stable treatment.
[0032] In this invention, the first support elements may have guide
pins arranged at opposite sides of each groove for guiding the
substrates being placed and preventing turnover of the substrates.
The substrates, when being placed on the first support elements,
can be guided reliably to predetermined positions. The substrates,
just as placed, can be prevented from turning over.
[0033] In this invention, each of the guide pins may have a base
projecting from the elastic member, and a guide portion formed on
an upper part of the base and projecting from the base toward one
of the substrates.
[0034] The guide portion, while serving to guide the substrate and
stabilize its position, permits the electrolyte solution to remain
between the base and a substrate surface. This construction can
lessen locations around the guide portion where the chemical
reaction does not take place.
[0035] In this invention, a junction between a left second support
unit and a right second support unit may have a notch pressing
mechanism for pressing notches of the substrates through elastic
members provided on inner surfaces of the left second support unit
and the right second support unit.
[0036] The notch pressing mechanism presses the elastic members
into the notches of the substrates. This can prevent the
electrolyte solution on the front and back surface sides of the
substrates from circulating through the notches, which could
otherwise cause concentration fluctuations.
[0037] In this invention, the notch pressing mechanism may include
a slide member provided on one of a left second support unit and a
right second support unit to be slidable toward centers of the
substrates, and a pressing member provided on the other of a left
second support unit and the a second support unit for pressing the
slide member when the left second support unit and the right second
support unit join each other.
[0038] When a left second support unit and a right second support
unit join each other, the slide member is pressed by the pressing
member, whereby the notches of the substrates are pressed by the
elastic member. Since the notch pressing mechanism is operable as
interlocked to the operation for joining the left second support
unit and the right second support unit, it is not necessary to
carry out special control.
[0039] In this invention, an elastic member provided on inner
surfaces of the first support elements may be harder than an
elastic member provided on inner surfaces of the second support
elements.
[0040] When the substrates are supported by the second support
elements, the positions of the substrates can be prevented from
shifting excessively to the first support elements. Therefore, in
some instances the lower circumferential surfaces and the remaining
circumferential surfaces of the substrates can be supported
substantially uniformly.
[0041] In this invention, the apparatus may further comprise foamed
materials provided for a junction between a left second support
unit and the first support unit, and for a junction between a right
second support unit and the first support unit.
[0042] The foamed materials can lessen a shock occurring at a time
of connection, and promote a sealed state at the junctions.
[0043] In another aspect of the invention, an anodizing apparatus
for causing an anodizing reaction on substrates immersed in an
electrolyte solution, comprises a storage tank for storing an
electrolyte solution of a first concentration; a substrate holder
mounted in the storage tank for holding a plurality of substrates,
with entire circumferential surfaces of the substrates in a
liquid-tight condition relative to the electrolyte solution of the
first concentration; a pair of electrode tanks arranged adjacent
the storage tank for storing an electrolyte solution of a second
concentration lower than the first concentration; electrodes
arranged in the pair of electrode tanks, respectively; and
ion-exchange membranes provided between the storage tank and the
pair of electrode tanks for permitting movement of ions between the
electrolyte solution in the storage tank and the electrolyte
solution in the pair of electrode tanks.
[0044] According to this invention, a plurality of substrates are
held by the substrate holder mounted in the storage tank, and the
electrodes arranged in the pair of electrode tanks are electrified.
Then, ions move between the pair of electrode tanks, which cause a
chemical reaction on the plurality of substrates through the
ion-exchange membranes. This enables batch treatment for treating a
plurality of substrates at a time. The second concentration of the
electrolyte solution stored in the electrode tanks is set lower
than the first concentration of the electrolyte solution stored in
the storage tank and contacting the substrates. Since the chemical
reaction is inhibited in the electrode tanks compared with that in
the storage tank, a local chemical reaction occurring to each of
the electrodes in the electrode tanks can be inhibited. As a
result, degradation of the electrodes can be inhibited,
contamination of the substrates can be prevented, and the operating
rate of the apparatus can be improved.
[0045] In this invention, the substrate holder may assume a
cylindrical appearance, and include through-bores disposed at one
end and the other end thereof in a direction of arrangement of the
substrates, the through-bores being aligned to the electrodes.
[0046] Since the electric field between the electrodes is directed
to the plurality of substrates via the through-bores, a chemical
reaction is produced efficiently.
[0047] In this invention, each of the electrodes may have a first
electrode member electrically connected to a power source and
maintained out of contact with the electrolyte solution, and a
second electrode member electrically connected to the first
electrode member and maintained in contact with the electrolyte
solution.
[0048] The first electrode member maintained out of contact with
the electrolyte solution is safe against deterioration.
[0049] In this invention, the second electrode member may be
homogeneous to the substrates treated in the substrate holder.
[0050] The materials forming the second electrode member are eluted
into the electrolyte solution. However, since the second electrode
member is homogenous to the substrates under treatment, the
substrates under treatment are prevented from being contaminated by
a heterogeneous substance.
[0051] In this invention, the apparatus may further comprise
partitions disposed between the storage tank and the pair of
electrode tanks, and having openings, respectively, the
ion-exchange membranes being provided in the openings.
[0052] This construction can permit ions to move between the pair
of electrode tanks through the ion-exchange membranes provided in
the openings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] For the purpose of illustrating the invention, there are
shown in the drawings several forms which are presently preferred,
it being understood, however, that the invention is not limited to
the precise arrangement and instrumentalities shown.
[0054] FIG. 1 is a front view in vertical section of an outline
construction of an anodizing apparatus according to this
invention;
[0055] FIG. 2 is a side view in vertical section of at the outline
construction of the anodizing apparatus;
[0056] FIG. 3 is a plan view of the outline construction of the
anodizing apparatus;
[0057] FIG. 4 includes views showing a substrate holder, in which
FIG. 4A is a plan view, FIG. 4B is a side view, and FIG. 4C is a
front view;
[0058] FIG. 5 is a front view of a first support unit;
[0059] FIG. 6 includes views showing the first support unit, in
which FIG. 6A is a plan view, and FIG. 6B is a section taken on
line A-A of FIG. 6A;
[0060] FIG. 7 includes views showing a second support unit, in
which FIG. 7A is a front view, FIG. 7B shows a left second support
unit, and FIG. 7C shows a right second support unit;
[0061] FIG. 8 includes schematic views showing operation at a time
of connecting the first support unit and second support unit, in
which FIG. 8A shows a separated state, and FIG. 8B shows a
connected state;
[0062] FIG. 9 includes schematic views showing operation at a time
of connecting the left second support unit and right second support
unit, in which FIG. 9A shows a separated state, and FIG. 9B shows a
connected state;
[0063] FIG. 10 includes schematic views showing states of a
substrate placed on the first support unit, in which FIG. 10A shows
a state of the substrate placed, and FIG. 10B shows a state of the
substrate pressed by the second support unit;
[0064] FIG. 11 is a schematic view showing a state at a time of
chemical reaction;
[0065] FIG. 12 includes views showing a modification of the first
support unit, in which FIG. 12A is a plan view, and FIG. 12B is a
view in vertical section;
[0066] FIG. 13 is a view showing a modification of the second
support unit;
[0067] FIG. 14 is a view showing a modification of the first
support unit and second support unit; and
[0068] FIG. 15 is a view showing another modification of the first
support unit and second support unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0069] A preferred embodiment of this invention will be described
in detail hereinafter with reference to the drawings.
[0070] FIG. 1 is a front view in vertical section of an outline
construction of an anodizing apparatus according to this invention.
FIG. 2 is a side view in vertical section of the outline
construction of the anodizing apparatus. FIG. 3 is a plan view of
the outline construction of the anodizing apparatus.
[0071] The anodizing apparatus in this embodiment has a function
for causing an anodizing reaction on a plurality of silicon
substrates at the same time, thereby to treat the substrates to be
porous, for example. This anodizing apparatus includes an outer
receptacle 1 and an inner receptacle 3. The inner receptacle 3 is
disposed inside the outer receptacle 1. For convenience of
illustration, the outer receptacle 1 and inner receptacle 3 are
omitted from FIG. 1.
[0072] The inner receptacle 3 has a pair of electrode tanks 5 and 7
and one storage tank 9. The storage tank 9 stores an electrolyte
solution. The storage tank 9 has an inner tank 11 and outer tanks
13. The electrolyte solution may be a mixed solution of
hydrofluoric acid, for example. The electrolyte solution is
supplied from a weighing tank, not shown, to the bottom of the
inner tank 11, and excess part thereof overflows into the outer
tanks 13 to be collected.
[0073] The storage tank 9 has a pair of covers 15 for opening and
closing a top opening thereof. The pair of covers 15 are shaped
rectangular in plan view (as shown in two-dot chain lines in FIG.
3). Each cover 15 is attached to a support arm 17 along a shorter
side of the storage tank 9. The support arm 17 has a distal portion
thereof attached to the cover 15, and a proximal portion extending
out of the outer receptacle 1.
[0074] A pair of air cylinders 19 are attached to one side surface
(left surface in FIG. 3) of the outer receptacle 1. These air
cylinders 19 are attached in a horizontal position to the outer
receptacle 1, with ends having actuating pieces movable forward and
backward as opposed to each other. As shown in FIG. 2, the air
cylinders 19 are attached to positions at vertically different
levels. The actuating pieces of the air cylinders 19 are connected
to the proximal ends of the support arms 17, respectively. When the
air cylinders 19 are operated to move the actuating pieces forward,
the pair of covers 15 interlocked to the support arms 17 will
approach each other and cover an upper central area of the inner
tank 11 (as shown in solid lines in FIG. 1). When the air cylinders
19 are operated in opposite directions to move the actuating pieces
backward, the pair of covers 15 interlocked to the support arms 17
will separate from each other and move from the positions over the
inner tank 11 to positions over the outer tanks 13 (as shown in
two-dot chain lines in FIG. 1).
[0075] The pair of air cylinders 19 correspond to the "cover drive
mechanism" in this invention.
[0076] The electrode tank 5 is formed on one side (left side in
FIGS. 2 and 3) of the inner tank 11. This electrode tank 5 stores
an electrolyte solution, and has an electrode 21 disposed in a
position immersed in the electrolyte solution. The electrode tank 7
is formed on the other side (right side in FIGS. 2 and 3) of the
inner tank 11. This electrode tank 7 also stores the electrolyte
solution, and has an electrode 23 disposed in a position immersed
in the electrolyte solution. These electrode tanks 5 and 7 store
the same type of electrolyte solution as supplied to the inner tank
11. However, it is preferred that its concentration is set lower
than that of the electrolyte solution in the inner tank 11. When,
for example, the electrolyte solution in the inner tank 11 has a
ratio of hydrofluoric acid solution:isopropyl alcohol:deionized
water at 1:1:1, the electrolyte solution in the electrode tanks 5
and 7, preferably, is 50 times thinner than the electrolyte
solution in the inner tank 11.
[0077] A negative electrode of a power source not shown is
connected to the electrode 21, for example, while a positive
electrode of the power source not shown is connected to the
electrode 23. The electrode 21, preferably, has a dual structure
including, for example, a metal 21a connected to the power source
not shown, and a silicon substrate 21b disposed on the side for
contacting the electrolyte solution. Similarly, the electrode 23,
preferably, has a dual structure including a metal 23a connected to
the power source not shown, and a silicon substrate 23b disposed on
the side for contacting the electrolyte solution. The metal can be
anything that has resistance to the electrolyte solution, such as
platinum, palladium, gold, silver or copper, for example. The
electrolyte solution given by way of example herein includes
hydrofluoric acid, and even if the metal has a certain level of
resistance, metal components will be eluted. However, since the
electrodes 21 and 23 have, on the electrolyte solution sides, the
silicon substrates 21b and 23b which are the same type of material
as the substrates under treatment, the substrates under treatment
can be prevented from being contaminated by a different type
metal.
[0078] Further, since the electrodes 21a and 23a are kept out of
contact with the electrolyte solution by interposition of the
silicon substrates 21b and 23b, degradation of the electrodes 21a
and 23a can be prevented.
[0079] Each of the above metals 21a and 23a corresponds to the
"first electrode member" in this invention. Each of the above
silicon substrates 21b and 23b corresponds to the "second electrode
member" in this invention.
[0080] A partition 25 between the electrode tank 5 and the inner
tank 11 has a circular opening 27, and an ion-exchange membrane 29
mounted in this opening 27. Similarly, a partition 31 between the
electrode tank 7 and the inner tank 11 has a circular opening 33,
and an ion-exchange membrane 35 mounted in this opening 33. The
ion-exchange membranes 29 and 35 may be formed of Nafion
(registered trademark) of E. I. du Pont de Nemours & Co., for
example. Preferably, the ion-exchange membranes 29 and 35 are used
as held between punching plates each having a plurality of holes.
This construction can prevent concentration fluctuations due to
expansion of the ion-exchange membranes 29 and 35 caused by osmotic
pressure, leading to variations in ion exchange action. As a
result, treating unevenness can be inhibited.
[0081] Reference is now made to FIGS. 3 through 7. FIG. 4 includes
views showing a substrate holder, in which FIG. 4A is a plan view,
FIG. 4B is a side view, and FIG. 4C is a front view. FIG. 5 is a
front view of a first support unit. FIG. 6 includes views showing
the first support unit, in which FIG. 6A is a plan view, and FIG.
6B is a section taken on line A-A of FIG. 6A. FIG. 7 includes views
showing a second support unit, in which FIG. 7A is a front view,
FIG. 7B shows a left second support unit, and FIG. 7C shows a right
second support unit.
[0082] A substrate holder 41 is mounted in the inner tank 11 of the
storage tank 9. This substrate holder 41 includes a holder base 43
and holder ends 45 and 47. The holder base 43 has a space for
accommodating a plurality of substrates. The holder ends 45 and 47
have through-bores 49 and 51 formed therein. The holder ends 45 and
47 have a cylindrical outward appearance, and O-rings 53 and 55 are
mounted on cylindrical outer peripheries thereof. These O-rings 53
and 55 are provided in order to attach the substrate holder 41 in a
liquid-tight condition to the partitions 25 and 31 by means of
mounting members not shown. In other words, the substrate holder 41
is disposed in a position to have the through-bores 49 and 51
aligned to the electrodes 21 and 23. This arrangement facilitates
passage of the electric field formed by the electrodes 21 and 23,
thereby efficiently causing a chemical reaction on a plurality of
substrates.
[0083] The holder base 43 has a first support unit 57 as shown in
FIGS. 5 and 6 (but not shown in FIG. 4). As shown in FIG. 5, the
first support unit 57, when seen from the front, presents an
arcuate shape having a chord shorter than the diameter of the
substrates or wafers W. The first support unit 57 has a plurality
of first support elements 59. In the case of treating 25 wafers W
at a time, for example, the first support unit 57 has 25 first
support elements 59 in the direction of arrangement of the wafers
W. Since the first support unit 57 is arcuate with the chord
shorter than the diameter of the wafers W, a lifter LF shown in
FIG. 5 can engage portions below maximum diameter portions of the
wafers W. Therefore, stress is hardly imposed on the wafers W at a
time of transportation, thereby preventing damage and the like to
the wafers W.
[0084] The first support elements 59 contact only lower parts of
circumferential surfaces of the wafers W to support these parts in
a liquid-tight condition. The first support elements 59 have
grooves 61 formed in upper surfaces thereof. The grooves 61 have a
width slightly larger than the thickness of wafers W. Guide pins 63
are mounted in positions opposed to one another across each groove
61. When seen from the plane direction of the wafers W, as shown in
FIG. 5, the guide pins 63 are arranged in three positions including
a middle position and right and left positions. Each guide pin 63
has a central axis extending toward the center of a wafer W. Each
guide pin 63 has a base 65 and a guide portion 67. An elastic
member 69 is applied to the surfaces of the first support elements
59. The base 65 of each guide pin 63 projects from the surface of
the elastic member 69, and the guide portion 67 is formed on an
upper part of the base 65. The guide portion 67 has a slope 71 on a
side thereof adjacent the groove 61, and protrudes from the base 65
toward the groove 61. The elastic member 69 is formed of a material
having resistance to the electrolyte solution, such as
tetrafluoroethylene resin, for example.
[0085] The first support elements 59 adjoin one another in the
direction of arrangement of the wafers W. The guide pins 63 of
adjoining first support elements 59 are mounted in staggered
(zigzag) positions. This configuration can shorten the first
support unit 57 in the direction of arrangement of the wafers W, to
attain compactness of the apparatus. The first support unit 57,
second support unit 73 and guide pins 63 are formed of a synthetic
resin having resistance to the electrolyte solution, such as vinyl
chloride resin (polyvinyl chloride, PVC), for example.
[0086] The substrate holder 41 has the second support unit 73
disposed on an upper portion thereof as shown in FIG. 7. The second
support unit 73 includes a left second support unit 75 and a right
second support unit 77. The left second support unit 75 and right
second support unit 77, when seen from the front, present a shape
of character C and a shape of reversed character C. The second
support unit 73 contacts and supports in a liquid-tight condition
the parts of the circumferential surfaces of the wafers W remaining
of the circumferential surfaces of the wafers W supported in the
liquid-tight condition by the first support unit 57. The left
second support unit 75 includes a plurality of left second support
elements 79 adjoining one another in the direction of arrangement
of the wafers W, each support element 79 supporting one wafer W.
The right second support unit 77 includes a plurality of right
second support elements 81 adjoining one another in the direction
of arrangement of the wafers W, each support element 81 supporting
one wafer W. Exhaust passages 83 are formed in an upper inner
surface at boundaries between adjacent left second support elements
79. The exhaust passages 83 are formed in two locations along the
circumferential surface of each wafer W. The exhaust passages 83
have upper openings thereof located above the level (sign SL in
FIG. 1) of the electrolyte solution stored in the storage tank 9.
Exhaust passages 85 are formed in an upper inner surface at
boundaries between adjacent right second support elements 81, as
between adjacent left second support elements 79. The exhaust
passages 85 are formed in two locations along the circumferential
surface of each wafer W. The left second support unit 75 has an
elastic member 87 applied to the inner surface thereof, and the
right second support unit 77 has an elastic member 89 applied
similarly. The elastic members 87 and 89 are applied in a way not
to block the exhaust passages 83 and 85.
[0087] The above elastic members 87 and 89 are formed of a material
having resistance to the electrolyte solution. This material may be
tetrafluoroethylene resin, for example, but preferably is softer
than the elastic member 69 of the first support unit 57. In other
words, the elastic member 69 of the first support unit 57,
preferably, is harder than the elastic members 87 and 89.
[0088] As shown in FIG. 1, the second support unit 73 is
constructed openable and closable, and attachable to and detachable
from the first support unit 57. Specifically, the left second
support unit 75 has pedestals 91, fulcrums 93, a rocking arm 95 and
connectors 97. The pedestals 91, with the first support unit 57
disposed in between, are fixed to the bottom of the inner tank 11.
The fulcrums 93 are arranged in portions at one end of the rocking
arm 95 attached to the pedestals 91. The other end of the rocking
arm 95 is fixed to an outer peripheral portion of the left second
support unit 75. The right second support unit 77 has pedestals 99,
fulcrums 101, a rocking arm 103 and connectors 105, as does the
left second support unit 75.
[0089] Each connector 97 has a suspension member 107, a slide pin
109 and a fixed member 111. The suspension member 107 is attached
to and suspended from a lower surface of one of the covers 15. The
suspension member 107 has a slot 113 formed to extend therethrough
in the direction of the plane of FIG. 1. The fixed member 111 is
fixed to an upper peripheral surface of the left second support
unit 75, and has the slide pin 109 inserted in the slot 113. The
slide pin 109 is freely movable in the slot 113. Although the
reference signs are omitted, the connectors 105 have the same
construction as the connectors 97. Thus, when the pair of air
cylinders 19 are operated to open the pair of covers 15, as shown
in two-dot chain lines in FIG. 1, the left second support unit 75
and right second support unit 77 rock away from each other about
the fulcrums 93 and 101, to open an area over and opposite lateral
areas of the substrate holder 41, leaving the first support unit 57
as it is. When the pair of air cylinders 19 are operated in reverse
directions to close the pair of covers 15, the left second support
unit 75 and right second support unit 77 rock toward each other
about the fulcrums 93 and 101, to close the area over and opposite
lateral areas of the substrate holder 41. As a result, wafers W are
placed in a sealed state in the substrate holder 41 relative to the
electrolyte solution in the inner tank 11. At this time, the forces
imparted from the left second support unit 75 and right second
support unit 77 act toward the centers of wafers W as indicated by
two-dot chain line arrows in FIG. 1.
[0090] As described above, the second support unit 73 is driven
between the closed position and open position by the pair of air
cylinders 19 which primarily drive the pair of covers 15. The air
cylinders 19 serving the dual purpose can simplify the construction
relating to drive, and facilitate control of various components at
times of transporting the wafers W. The pair of air cylinders 19
correspond to the "drive mechanism" in this invention.
[0091] Reference is now made to FIG. 8. FIG. 8 includes schematic
views showing operation at a time of connecting the first support
unit and second support unit, in which FIG. 8A shows a separated
state, and FIG. 8B shows a connected state.
[0092] The first support unit 57 has buffer members 117 attached to
side surfaces 115 thereof. The buffer members 117 may be formed of
a sponge material having resistance to the electrolyte solution,
for example. These buffer members 117 lessen a shock occurring when
the second support unit 73 moves into contact with the first
support unit 57, and also maintain a liquid-tight condition at
junctions. The elastic member 69 of the first support unit 57 has
ends extending outward of the buffer members 117. This feature can
maintain the liquid-tight condition at the junctions when the first
support unit 57 and second support unit 73 in a separated state as
shown in FIG. 8A are connected as shown in FIG. 8B.
[0093] Reference is made to FIG. 9. FIG. 9 includes schematic views
showing operation at a time of connecting the left second support
unit and right second support unit, in which FIG. 9A shows a
separated state, and FIG. 9B shows a connected state.
[0094] The left second support unit 75 has a slide member 119. This
slide member 119 is mounted in contact with an outer surface of the
elastic member 87, and attached to an upper right surface of the
left second support unit 75 to be slidable up and down (in
directions toward and away from the centers of wafers W) in the
state of the left second support unit 75 being closed. The slide
member 119 has a slope 121 inclined toward the right second support
unit 77. The right second support unit 77 has a pressing member
123. This pressing member 123 is fixedly attached to an upper left
surface of the right second support unit 77. The pressing member
123 has a slope 125 formed thereon which has a gentler inclination
angle than the slope 121. The above slide member 119 and pressing
member 123 constitute a notch pressing mechanism 127. Thus, when
the left second support unit 75 and right second support unit 77 in
a separated state as shown in FIG. 9A are connected as shown in
FIG. 9B, the pressing member 123 will move the slide member 119
toward the centers of wafers W, whereby the elastic member 87 of
the left second support unit 75 is moved toward notches N of wafers
W. As a result, the notches N of wafers W are covered by the
elastic member 87. This can prevent the electrolyte solution on
both surfaces of each wafer W from circulating through the notch N.
This construction can inhibit concentration fluctuations of the
electrolyte solution to improve the uniformity of treatment.
[0095] The notch pressing mechanism 127 may be modified such that
the pressing member 123 is attached to the left second support unit
75, and the slide member 119 to the right second support unit
77.
[0096] Reference is made to FIG. 10. FIG. 10 includes schematic
views showing states of a substrate placed on the first support
unit, in which FIG. 10A shows a state of the substrate placed, and
FIG. 10B shows a state of the substrate pressed by the second
support unit.
[0097] When, with the second support unit 73 separated from the
first support unit 57, a lifter not shown places wafers W on the
first support unit 57, the lower surface of each wafer W is guided
by the guide pins 63 and located above the groove 61 as shown in
FIG. 10A. And when the second support unit 73 is connected to the
first support unit 57 as described above, each wafer W is pressed
from upper right and left of the wafer W. Then, as shown in FIG.
10B, the elastic member 69 is pressed by the lower surface of the
wafer W into the groove 61. The elastic member 69 of the first
support unit 57 is set harder than the elastic members 87 and 89 of
the second support unit 73. Consequently, when the second support
unit 73 supports and presses the wafers W, the positions of the
wafers W cannot move excessively close to the first support unit
57. Therefore, the entire circumferential surfaces of the wafers W
including the lower parts and the remaining parts thereof can be
supported uniformly and in a liquid-tight condition relative to the
electrolyte solution. Since the circumferential surface of each
wafer W enters the groove 61, parts of the front and back surfaces
including the circumferential surface of the wafer W can be
supported, and the electrolyte solution between adjoining wafers W
will not circulate. As a result, the concentration of the
electrolyte solution acting on the wafers W remains stable, to
realize stable treatment.
[0098] As shown in FIG. 11, spaces sp occur between the bases 65 of
the guide pins 63 and the surfaces of each wafer W. These spaces sp
permit the electrolyte solution to stagnate between the bases 65
and the surfaces of the wafer W. This minimizes locations where the
chemical reaction does not easily take place at the time of
anodizing treatment.
[0099] The anodizing apparatus constructed as described above first
supplies the electrolyte solution of predetermined concentration to
the storage tank 9, and keeps the electrolyte solution of
predetermined concentration to the pair of electrode tanks 5 and 7.
Next, the pair of air cylinders 19 are operated to open the pair of
covers 15 (see the two-dot chain lines in FIG. 1). At this time, as
interlocked to this operation, the left second support unit 75 and
right second support unit 77 separate from each other, and the
electrolyte solution in the storage tank 9 flows into the substrate
holder 41. Next, a plurality of wafers W are transported by the
lifter, and placed on the first support unit 57 (see FIG. 10A).
Next, the pair of air cylinders 19 are operated in the opposite
directions to close the pair of covers 15 (see the solid lines in
FIG. 1). At this time, as interlocked to this operation, the left
second support unit 75 and right second support unit 77 connect to
the first support unit 57 (see FIGS. 8A and 8B), which operates the
notch pressing mechanism 127 (see FIGS. 9A and 9B). Consequently,
the plurality of wafers W, with the entire circumferential surfaces
including the notches N thereof sealed up, are stored in the
substrate holder 41 in a liquid-tight condition relative to the
electrolyte solution in the storage tank 9. When, in this state,
the electrode 21 and electrode 23 are electrified, a chemical
reaction takes place to render the plurality of wafers W porous.
Although gas is generated by the anodizing reaction, gas bubbles
are discharged out of the substrate holder 41 through the exhaust
passages 83 and 85 of the second support unit 73. This can prevent
treating unevenness due to the gas bubbles.
[0100] Upon completion of a chemical reaction process of a
predetermined time, the electrode 21 and electrode 23 are
de-electrified, and the pair of air cylinders 19 are operated to
open the pair of covers 15. As interlocked to the latter operation,
the left second support unit 75 and right second support unit 77
are separated from each other, and the electrolyte solution in the
storage tank 9 flows into the substrate holder 41. In this way, the
electrolyte solution is refreshed for treatment of a next batch of
wafers W. Next, the plurality of treated wafers W are held and
transported out of the substrate holder 41 by the lifter.
[0101] According to the apparatus in this embodiment, the pair of
air cylinders 19 separate the first support unit 57 and second
support unit 73 arranged in the storage tank 9. In this state, a
plurality of wafers W are respectively placed between the first
support elements 59 of the first support unit 57, whereby only
lower portions of the circumferential surfaces of the wafers W are
supported in a liquid-tight condition relative to the electrolyte
solution. When the second support unit 73 is connected to the first
support unit 57 by the pair of air cylinders 19, the plurality of
wafers W are supported by the left second support elements 79 and
right second support elements 81, with the remaining portions of
the circumferential surfaces of the wafers W put in a liquid-tight
condition relative to the electrolyte solution. Consequently, the
entire circumferential surfaces of the wafers W are now in the
liquid-tight condition relative to the electrolyte solution. After
the anodizing reaction is completed, the second support unit 73 is
separated from the first support unit 57 by the pair of air
cylinders 19, and the plurality of wafers W supported by the first
support unit 57 are unloaded therefrom. Thus, the substrate holder
41 having the first support unit 57 and second support unit 73
attachable to and detachable from each other by the pair of air
cylinders 19 enables a plurality of wafers W to be mechanically
loaded into and unloaded from the storage tank. As a result, the
anodizing apparatus provided is well suited for automation and
batch treatment.
[0102] According to the apparatus in this embodiment, a plurality
of wafers W are held by the substrate holder 41 mounted in the
storage tank 9, and the electrodes 21 and 23 arranged in the pair
of electrode tanks 5 and 7 are electrified. Then, ions move between
the pair of electrode tanks 21 and 23, which cause a chemical
reaction on the plurality of wafers W through the ion-exchange
membranes 29 and 35. This enables batch treatment for treating a
plurality of wafers W at a time. The concentration of the
electrolyte solution stored in the electrode tanks 5 and 7 is set
lower than the concentration of the electrolyte solution stored in
the storage tank 9. Since the chemical reaction is inhibited in the
electrode tanks 5 and 7 compared with that in the storage tank 9, a
local chemical reaction occurring to each of the electrodes 21 and
23 in the electrode tanks 5 and 7 can be inhibited. As a result,
degradation of the electrodes 21 and 23 can be inhibited, and the
operating rate of the apparatus can be improved.
[0103] This invention is not limited to the foregoing embodiment,
but may be modified as follows:
[0104] (1) In the foregoing embodiment, the first support unit 57
includes the first support elements 59 each having a pair of guide
pins 63 for acting on the front and back surfaces of each wafer W,
such guide pins 63 being in zigzag positions in the direction of
arrangement of the wafers W. However, the first support unit 57 of
this invention is not limited to such construction, but may be
constructed as shown in FIG. 12, for example. FIG. 12 includes
views showing a modification of the first support unit, in which
FIG. 12A is a plan view, and FIG. 12B is a view in vertical
section.
[0105] Each of these first support elements 59A includes guide pins
63A on both sides of each groove 61. Each guide pin 63A has a guide
67A disposed on a base 65A and protruding toward the grooves 61.
This guide 67A has guide faces 71A on both sides in the direction
of arrangement of wafers W. The guide pins 63A are not arranged
zigzag, but arranged linearly in the direction of arrangement of
wafers W. Since each guide pin 63A has the guide faces 71A on both
sides, adjoining first support elements 59A can share one guide pin
63A. The first support unit 57A can be shortened in the direction
of arrangement of wafers W, to contribute to compactness of the
apparatus.
[0106] (2) In the foregoing embodiment, the left second support
unit 75 and right second support unit 77 are rocked about fulcrums
93 and 101 at the bottom of the storage tank 9. This invention is
not limited to this construction. For example, a construction as
shown in FIG. 13 may be employed. FIG. 13 is a view showing a
modification of the second support unit.
[0107] This modification provides a second support unit 73A
including a left second support unit 75A and a right second support
unit 77A having an upper fulcrum 129. Although this construction
requires a mechanism for displacing the second support unit 73A at
times of loading and unloading wafers W, the mechanism in the
storage tank 9 becomes unnecessary, and thus can simplify the
construction of the storage tank 9.
[0108] (3) The foregoing embodiment provides the first support unit
57 and second support unit 73, and the second support unit 73
consists of the left second support unit 75 and right second
support unit 77. This invention is not limited to the above
construction, but may employ a construction as shown in FIG. 14,
for example. FIG. 14 is a view showing a modification of the first
support unit and second support unit.
[0109] With these first support unit 57B and second support unit
73B, the second support unit 73B is not divided. The first support
unit 57B and second support unit 73B are divided up and down
adjacent the maximum diameter of wafers W. The first support unit
57B and second support unit 73B are constructed such that the
second support unit 73B is rockable about a fulcrum 131 relative to
the first support unit 57B. This construction can reduce the number
of parts to attain low cost. The construction of the apparatus can
also be simplified.
[0110] (4) The foregoing embodiment has been described as treating
circular wafers W, but this invention can treat also other
substrates than the circular wafers W, such as square substrates,
for example. For this purpose, a construction as shown in FIG. 15,
for example, may be employed. FIG. 15 is a view showing another
modification of the first support unit and second support unit.
[0111] This modification treats square substrates W in a position
having diagonally opposed corners pointing in the vertical
(horizontal) direction. In this case, a first support unit 57C is
V-shaped. Further, a second support unit 73C is divided into a left
second support unit 75C and a right second support unit 77C. Such
construction, combined with a construction similar to that in the
foregoing embodiment, can treat square substrates.
[0112] For treating the square substrates W, the modifications (2)
and (3) above may also be employed.
[0113] (5) The foregoing embodiment provides the notch pressing
mechanism 127. However, the notch pressing mechanism 127 is not
essential to this invention.
[0114] (6) The foregoing embodiment provides the exhaust passages
83 and 85. Such exhaust passages 83 and 85 are not required where
the influence of bubbles generated by the treatment is small or
negligible.
[0115] (7) In the foregoing embodiment, the second support unit 73
is driven by the pair of air cylinders 19 which open and close the
pair of covers 15. Instead, a drive mechanism may be provided for
exclusive use in driving the second support unit 73.
[0116] (8) In the foregoing embodiment, the electrodes 21 and 23
have the dual structure including metals 21a, 23a and silicon
substrates 23a, 23b. However, this construction is not
indispensable to this invention. That is, the electrodes 21 and 23
may have only the metals 21a, 23a. Even with this construction,
since the concentration of the electrolyte solution in the
electrode tanks 5 and 7 is set low, degradation of the metals 21a
and 23a can be inhibited.
[0117] This invention may be embodied in other specific forms
without departing from the spirit or essential attributes thereof
and, accordingly, reference should be made to the appended claims,
rather than to the foregoing specification, as indicating the scope
of the invention.
* * * * *