U.S. patent application number 09/955110 was filed with the patent office on 2002-01-31 for heating apparatus for bump bonding, bump bonding method and bump forming apparatus, and semiconductor wafer.
Invention is credited to Imanishi, Makoto, Kanayama, Shinji, Mae, Takaharu, Narita, Shoriki, Watanabe, Nobuhisa.
Application Number | 20020011479 09/955110 |
Document ID | / |
Family ID | 17836055 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011479 |
Kind Code |
A1 |
Narita, Shoriki ; et
al. |
January 31, 2002 |
Heating apparatus for bump bonding, bump bonding method and bump
forming apparatus, and semiconductor wafer
Abstract
An object of the present invention is to provide a bump-bonding
heating apparatus, a bump bonding method and a bump forming
apparatus which do not involve large-sized apparatus configuration
and which are easy to handle, and a semiconductor wafer in which
bumps are formed by using the bump bonding method. The bump-bonding
heating apparatus has a wafer turning member, a turning unit and a
wafer heating unit. The turning member is turned by the turning
unit without turning the wafer heating unit, whereby a
semiconductor wafer mounted on the turning member is turned. Like
this, since the wafer heating unit is not turned, the apparatus
configuration can be made compact. Since the turning member is
turned directly by the turning unit, the turning angle of the
semiconductor wafer can be implemented with higher precision as
compared with the conventional gas floating type turning
method.
Inventors: |
Narita, Shoriki; (Osaka-fu,
JP) ; Imanishi, Makoto; (Osaka-fu, JP) ; Mae,
Takaharu; (Osaka-fu, JP) ; Watanabe, Nobuhisa;
(Osaka-fu, JP) ; Kanayama, Shinji; (Nara-ken,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
17836055 |
Appl. No.: |
09/955110 |
Filed: |
September 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09955110 |
Sep 19, 2001 |
|
|
|
09690746 |
Oct 18, 2000 |
|
|
|
Current U.S.
Class: |
219/390 ;
219/392; 219/393; 219/400 |
Current CPC
Class: |
H01L 21/68 20130101;
H01L 21/67103 20130101 |
Class at
Publication: |
219/390 ;
219/392; 219/393; 219/400 |
International
Class: |
C23C 006/00; F27B
005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 1999 |
JP |
11-296631 |
Claims
What is claimed is:
1. A heating apparatus for bump bonding, comprising: a wafer
turning member, on which a semiconductor wafer is placed for bump
bonding, for rotating the placed semiconductor wafer on the wafer
turning member in a circumferential direction of the wafer; a
turning unit for rotating the wafer turning member along the
circumferential direction; and a wafer heating unit, on which the
wafer turning member is placed, for heating the semiconductor wafer
to a bump bonding temperature via the wafer turning member, the
wafer heating unit being disposed in spite of the rotation of the
wafer turning member.
2. The heating apparatus for bump bonding according to claim 1,
further comprising a control unit for controlling operation of the
turning unit so that the wafer turning member is rotated at a
turning angle required for the semiconductor wafer placed on the
wafer turning member.
3. The heating apparatus for bump bonding according to claim 1,
wherein the wafer turning member has a wafer stage on which the
semiconductor wafer is placed, and a turntable on which the wafer
stage is placed and for holding the wafer stage by suction
operation, the turntable being placed on the wafer heating
unit.
4. The heating apparatus for bump bonding according to claim 2,
wherein the wafer turning member has a wafer stage on which the
semiconductor wafer is placed, and a turntable on which the wafer
stage is placed and for holding the wafer stage by suction
operation, the turntable being placed on the wafer heating
unit.
5. The heating apparatus for bump bonding according to claim 4,
wherein the wafer heating unit has: a turntable mounting plate on
which the turntable is placed; a heater inserted and extended along
a hole, the hole being formed in the turntable mounting plate along
a direction perpendicular to a thicknesswise direction of the
turntable mounting plate; and a support member for supporting the
turntable mounting plate, the support members extending along a
direction perpendicular to both directions of the thicknesswise
direction and the extending direction of the heater.
6. The heating apparatus for bump bonding according to claim 5,
wherein the turntable has teeth formed at a peripheral part of the
turntable, and the turning unit comprises a driving source, a gear
wheel engaged with the teeth of the turntable, and a
rotational-force transmission mechanism for preventing heat of the
turntable from transferring to the driving source and for
transmitting a driving force generated by the driving source to the
gear wheel to thereby turn the gear wheel.
7. The heating apparatus for bump bonding according to claim 1,
further comprises a lifter unit for lifting and lowering the wafer
turning member between a heating position and a transfer position
along a thicknesswise direction of the semiconductor wafer placed
on the wafer turning member, the heating position being a position
where the wafer turning member makes contact with the wafer heating
unit so that the semiconductor wafer is heated to the bump bonding
temperature via the wafer turning member, and the transfer position
being a position where the wafer turning member is positioned when
the wafer turning member is turned.
8. The heating apparatus for bump bonding according to claim 4,
further comprises a lifter unit for lifting and lowering the wafer
turning member between a heating position and a transfer position
along a thicknesswise direction of the semiconductor wafer placed
on the wafer turning member, the heating position being a position
where the wafer turning member makes contact with the wafer heating
unit so that the semiconductor wafer is heated to the bump bonding
temperature via the wafer turning member, and the transfer position
being a position where the wafer turning member is positioned when
the wafer turning member is turned.
9. The heating apparatus for bump bonding according to claim 5,
further comprises a lifter unit for lifting and lowering the wafer
turning member between a heating position and a transfer position
along a thicknesswise direction of the semiconductor wafer placed
on the wafer turning member, the heating position being a position
where the wafer turning member makes contact with the wafer heating
unit so that the semiconductor wafer is heated to the bump bonding
temperature via the wafer turning member, and the transfer position
being a position where the wafer turning member is positioned when
the wafer turning member is turned.
10. The heating apparatus for bump bonding according to claim 6,
further comprises a lifter unit for lifting and lowering the wafer
turning member between a heating position and a transfer position
along a thicknesswise direction of the semiconductor wafer placed
on the wafer turning member, the heating position being a position
where the wafer turning member makes contact with the wafer heating
unit so that the semiconductor wafer is heated to the bump bonding
temperature via the wafer turning member, and the transfer position
being a position where the wafer turning member is positioned when
the wafer turning member is turned.
11. The heating apparatus for bump bonding according to claim 1,
further comprising: a blow unit for floating the semiconductor
wafer placed on the wafer turning member from the wafer turning
member by gas blow; and a regulating unit for performing positional
regulation of the semiconductor wafer on the wafer turning member
while the semiconductor wafer is floating from the wafer turning
member.
12. The heating apparatus for bump bonding according to claim 5,
further comprising: a blow unit for floating the semiconductor
wafer placed on the wafer turning member from the wafer turning
member by gas blow; and a regulating unit for performing positional
regulation of the semiconductor wafer on the wafer turning member
while the semiconductor wafer is floating from the wafer turning
member.
13. The heating apparatus for bump bonding according to claim 10,
further comprising: a blow unit for floating the semiconductor
wafer placed on the wafer turning member from the wafer turning
member by gas blow; and a regulating unit for performing positional
regulation of the semiconductor wafer on the wafer turning member
while the semiconductor wafer is floating from the wafer turning
member.
14. The heating apparatus for bump bonding according to claim 1,
wherein the semiconductor wafer is a wafer on which SAW filter
devices are formed, and when the SAW filter devices are formed
along a skewed direction which is skewed to a crystal orientation
of the wafer prior to formation of the SAW filter devices, the
turning angle required for the semiconductor wafer placed on the
wafer turning member by operation control of the turning unit is an
angle which depends on a difference between the crystal orientation
and the skewed direction.
15. The heating apparatus for bump bonding according to claim 13,
wherein the semiconductor wafer is a wafer on which SAW filter
devices are formed, and when the SAW filter devices are formed
along a skewed direction which is skewed to a crystal orientation
of the wafer prior to formation of the SAW filter devices, the
turning angle required for the semiconductor wafer placed on the
wafer turning member by operation control of the turning unit is an
angle which depends on a difference between the crystal orientation
and the skewed direction.
16. A bump forming apparatus which comprises the heating apparatus
for bump bonding as defined in claim 1.
17. A bump forming method comprising: mounting a semiconductor
wafer, on which bumps are to be formed, onto a wafer turning
member; turning only the wafer turning member with the
semiconductor wafer placed thereon along a circumferential
direction of the semiconductor wafer at a turning angle required
for the semiconductor wafer without turning a wafer heating unit
provided for heating the semiconductor wafer to a bump bonding
temperature via the wafer turning member; and after the turning,
bonding the bumps on the semiconductor wafer at the bump bonding
temperature.
18. The bump forming method according to claim 17, further
comprising, after mounting the semiconductor wafer onto the wafer
turning member and before turning the wafer turning member,
performing positional regulation of the semiconductor wafer on the
wafer turning member by floating the semiconductor wafer from the
wafer turning member.
19. A semiconductor wafer on which a bump is formed by the bump
bonding method as defined in claim 17.
20. A semiconductor wafer on which bumps are formed in a circuit by
a process comprising, after forming the circuit along a direction
which is different from a crystal orientation of the semiconductor
wafer and is skewed with respect to the crystal orientation,
turning the semiconductor wafer at an angle which depends on a
difference between the crystal orientation and the skewed
direction.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a bump-bonding heating
apparatus for heating a semiconductor wafer placed on the heating
apparatus to a bump bonding temperature in a process of forming
bumps at electrode portions on circuits formed on the semiconductor
wafer, a bump bonding method to be carried out by using the
bump-bonding heating apparatus, a bump forming apparatus equipped
with the bump-bonding heating apparatus, and a semiconductor wafer
having bumps bonded by the bump forming apparatus.
[0002] Conventionally, a bump forming apparatus is equipped with
the bump-bonding heating apparatus. As shown in FIGS. 24 and 25, in
the conventional bump-bonding heating apparatus 1, gas is jetted
out, through gas jet paths 4 opened at a heat stage 2, to a
semiconductor wafer 3 which has been carried into the bump-bonding
heating apparatus and placed on the heat stage 2 so that the
semiconductor wafer 3 is heated to a bump bonding temperature. By
this gas jet, the semiconductor wafer 3 is rotated
circumferentially of the semiconductor wafer 3 on the heat stage 2
so as to be set to a preset rotational angle. For such a
gas-floating type direct turning method for the semiconductor wafer
3, only a gas supply unit 5 needs to be provided as a structure for
turning the semiconductor wafer 3. This allows the bump-bonding
heating apparatus 1 to be compacted, thus the direct turning method
being preferable.
[0003] However, the bump-bonding heating apparatus of the above
structure has the following problems. That is, in the case where
the semiconductor wafer 3 is a charge-producing semiconductor
substrate that produces charges from temperature differences due to
the heating to the bump bonding temperature or other reasons, the
charge-producing semiconductor substrate, when mounted on the heat
stage 2, is electrostatically adhered onto the heat stage 2 by the
electrification of the charge-producing semiconductor substrate.
Also, in order to turn the semiconductor wafer 3 to the preset
rotational angle, it would be necessary to control a pressure, flow
rate and the like of the gas jet according to a size and weight of
the semiconductor wafer 3, making the apparatus difficult to
handle. It is also difficult to turn the semiconductor wafer 3 to
the preset rotational angle at high accuracy.
[0004] Meanwhile, without adopting the gas-floating type turning
method for the semiconductor wafer 3, a structure in which the heat
stage 2 with the semiconductor wafer 3 held thereto is rotated
could be conceived. This structure, however, would involve upsizing
the apparatus, disadvantageously.
SUMMARY OF THE INVENTION
[0005] The present invention having been accomplished with a view
to solving these and other problems, an object of the invention is
to provide a heating apparatus for bump bonding which does not
involve large-sized apparatus configuration and which is easy to
handle, a bump bonding method to be executed in the heating
apparatus for bump bonding, a bump forming apparatus equipped with
the heating apparatus for bump bonding, and a semiconductor wafer
having bumps bonded by the bump forming apparatus.
[0006] In order to achieve the above object, the present invention
has the following constitutions.
[0007] In a first aspect of the invention, there is provided a
heating apparatus for bump bonding, comprising:
[0008] a wafer turning member, on which a semiconductor wafer is
placed for bump bonding, for rotating the placed semiconductor
wafer on the wafer turning member in a circumferential direction of
the wafer;
[0009] a turning unit for rotating the wafer turning member along
the circumferential direction; and
[0010] a wafer heating unit, on which the wafer turning member is
placed, for heating the semiconductor wafer to a bump bonding
temperature via the wafer turning member, the wafer heating unit
being disposed in spite of the rotation of the wafer turning
member.
[0011] In the first aspect of the invention, the heating apparatus
for bump bonding may further comprise a control unit for
controlling operation of the turning unit so that the wafer turning
member is rotated at a turning angle required for the semiconductor
wafer placed on the wafer turning member.
[0012] In the heating apparatus for bump bonding, the wafer turning
member may have a wafer stage on which the semiconductor wafer is
placed, and a turntable on which the wafer stage is placed and for
holding the wafer stage by suction operation, the turntable being
placed on the wafer heating unit.
[0013] In the heating apparatus for bump bonding, the wafer heating
unit may have a turntable mounting plate on which the turntable is
placed; a heater inserted and extended along a hole, the hole being
formed in the turntable mounting plate along a direction
perpendicular to a thicknesswise direction of the turntable
mounting plate; and a support member for supporting the turntable
mounting plate, the support members extending along a direction
perpendicular to both directions of the thicknesswise direction and
the extending direction of the heater.
[0014] In the heating apparatus for bump bonding, the turntable may
have teeth formed at a peripheral part of the turntable, and
[0015] the turning unit comprises a driving source, a gear wheel
engaged with the teeth of the turntable, and a rotational-force
transmission mechanism for preventing heat of the turntable from
transferring to the driving source and for transmitting a driving
force generated by the driving source to the gear wheel to thereby
turn the gear wheel.
[0016] The heating apparatus for bump bonding may further comprise
a lifter unit for lifting and lowering the wafer turning member
between a heating position and a transfer position along a
thicknesswise direction of the semiconductor wafer placed on the
wafer turning member,
[0017] the heating position being a position where the wafer
turning member makes contact with the wafer heating unit so that
the semiconductor wafer is heated to the bump bonding temperature
via the wafer turning member, and the transfer position being a
position where the wafer turning member is positioned when the
wafer turning member is turned.
[0018] The heating apparatus for bump bonding may further comprise
a blow unit for floating the semiconductor wafer placed on the
wafer turning member from the wafer turning member by gas blow, and
a regulating unit for performing positional regulation of the
semiconductor wafer on the wafer turning member while the
semiconductor wafer is floating from the wafer turning member.
[0019] In the heating apparatus for bump bonding, the semiconductor
wafer is a wafer on which SAW filter devices are formed, and when
the SAW filter devices are formed along a skewed direction which is
skewed to a crystal orientation of the wafer prior to formation of
the SAW filter devices, the turning angle required for the
semiconductor wafer placed on the wafer turning member by operation
control of the turning unit is an angle which depends on a
difference between the crystal orientation and the skewed
direction.
[0020] In a second aspect of the invention, there is provided a
bump bonding method comprising:
[0021] mounting a semiconductor wafer, on which bumps are to be
formed, onto a wafer turning member;
[0022] turning only the wafer turning member with the semiconductor
wafer placed thereon along a circumferential direction of the
semiconductor wafer at a turning angle required for the
semiconductor wafer without turning a wafer heating unit provided
for heating the semiconductor wafer to a bump bonding temperature
via the wafer turning member; and
[0023] after the turning, bonding the bumps on the semiconductor
wafer at the bump bonding temperature.
[0024] In a third aspect of the invention, there is provided a bump
forming apparatus which comprises the heating apparatus for bump
bonding of the first aspect.
[0025] In a fourth aspect of the invention, there is provided a
semiconductor wafer on which a bump is formed by the bump bonding
method of the second aspect.
[0026] In a fifth aspect of the invention, there is provided a
semiconductor wafer on which bumps are formed in a circuit by a
process comprising, after forming the circuit along a direction
which is different from a crystal orientation of the semiconductor
wafer and is skewed with respect to the crystal orientation,
turning the semiconductor wafer at an angle which depends on a
difference between the crystal orientation and the skewed
direction.
[0027] As described in detail above, according to the heating
apparatus for bump bonding in the first aspect of the present
invention, as well as to the bump bonding method in the second
aspect, the apparatus has a turning member, a turning unit and a
wafer heating unit, wherein the turning member is turned by the
turning unit without turning the wafer heating unit so that the
semiconductor wafer mounted on the turning member is turned.
Therefore, since the wafer heating unit is not turned, an apparatus
configuration can be compacted. Besides, since the turning member
is turned directly by the turning unit, a turning angle of the
semiconductor wafer can be implemented with higher accuracy as
compared with a conventional gas floating type.
[0028] Also, in the bump forming apparatus equipped with the
aforementioned heating apparatus for bump bonding in the third
aspect of the invention, the turning angle of the semiconductor
wafer can be controlled with high accuracy as described above.
Therefore, bump forming positions on the semiconductor wafer can be
controlled with higher accuracy as compared with the conventional
apparatus.
[0029] In the semiconductor wafer of the fourth aspect of the
invention, on which bumps are bonded with the aforementioned bump
bonding method of the second aspect, the turning angle of the
semiconductor wafer can be controlled with high accuracy as
described above. Therefore, bumps can be formed at bump forming
positions on the semiconductor wafer with higher accuracy as
compared with the conventional counterpart.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] These and other aspects and features of the present
invention will become clear from the following description taken in
conjunction with the preferred embodiments thereof with reference
to the accompanying drawings, in which:
[0031] FIG. 1 is a perspective view of a bump-bonding heating
apparatus according to an embodiment of the present invention;
[0032] FIG. 2 is a sectional view of the bump-bonding heating
apparatus shown in FIG. 1;
[0033] FIG. 3 is a perspective view of a bump forming apparatus
according to an embodiment of the invention;
[0034] FIG. 4 is a perspective view showing a wafer stage part
provided in the bump-bonding heating apparatus shown in FIG. 1;
[0035] FIG. 5 is a perspective view showing a turntable provided in
the bump-bonding heating apparatus shown in FIG. 1;
[0036] FIG. 6 is a perspective view showing a heating unit provided
in the bump-bonding heating apparatus shown in FIG. 1;
[0037] FIG. 7 is a perspective view showing guide rollers provided
in the bump-bonding heating apparatus shown in FIG. 1;
[0038] FIG. 8 is a perspective view showing a modification example
of the guide rollers shown in FIG. 7;
[0039] FIG. 9 is a perspective view showing a part for lifting and
lowering the guide rollers provided in the thick shown in FIG.
1;
[0040] FIG. 10 is a view in which the turntable and the wafer stage
provided in the bump-bonding heating apparatus shown in FIG. 1 are
positioned at a heating position;
[0041] FIG. 11 is a view in which the turntable and the wafer stage
provided in the bump-bonding heating apparatus shown in FIG. 1 are
positioned at a transfer position;
[0042] FIG. 12 is a view showing a relationship between the
turntable and the guide rollers provided in the bump-bonding
heating apparatus shown in FIG. 1;
[0043] FIG. 13 is a perspective view of a wafer regulating unit
provided in the bump-bonding heating apparatus shown in FIG. 1;
[0044] FIG. 14 is a flowchart showing operation of the bump-bonding
heating apparatus shown in FIG. 1;
[0045] FIG. 15 is a view showing a state in which a wafer is
carried into the bump-bonding heating apparatus shown in FIG.
1;
[0046] FIG. 16 is a view of a state that the bump-bonding heating
apparatus shown in FIG. 1 is lifted to the transfer position for
reception of the wafer;
[0047] FIG. 17 is a view of a state that the wafer has been
received by the bump-bonding heating apparatus shown in FIG. 1;
[0048] FIG. 18 is a view showing a state that the wafer has been
received by the bump-bonding heating apparatus shown in FIG. 1 and
returned to the heating position;
[0049] FIG. 19 is a plan view showing a state in which the wafer is
mounted on the bump-bonding heating apparatus shown in FIG. 1;
[0050] FIG. 20 is a view showing a state in which the wafer
regulating unit provided in the bump-bonding heating apparatus
shown in FIG. 1 performs wafer regulation;
[0051] FIG. 21 is a plan view showing a state after the wafer
regulating operation by the wafer regulating unit provided in the
bump-bonding heating apparatus shown in FIG. 1 has been done;
[0052] FIG. 22 is a view showing a conventional semiconductor wafer
in which circuits are formed along the crystal orientation of the
semiconductor wafer;
[0053] FIG. 23 is a view showing a semiconductor wafer in which
circuits are formed along a direction skewed with respect to the
crystal orientation of the semiconductor wafer;
[0054] FIG. 24 is a perspective view of a bump-bonding heating
apparatus according to a conventional art; and
[0055] FIG. 25 is a view showing a state in which a wafer is
floated by gas jet-out performed in the bump-bonding heating
apparatus according to the conventional art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] Before the description of the present invention proceeds, it
is to be noted that like parts are designated by like reference
numerals throughout the accompanying drawings.
[0057] Hereinbelow, a heating apparatus for bump bonding
(hereinafter, referred to as "a bump-bonding heating apparatus")
which is an embodiment according to the present invention, a bump
bonding method to be carried out by the bump-bonding heating
apparatus, a bump forming apparatus equipped with the bump-bonding
heating apparatus, and a semiconductor wafer in which bumps are
formed by using the bump bonding method are described with
reference to the accompanying drawings.
[0058] In this embodiment, a semiconductor wafer to be processed is
exemplified by a charge-producing semiconductor substrate that
produces charges, thereby being electrified, due to temperature
changes from room temperature to a bump bonding temperature. This
embodiment is suitable for a processing of, among others, a
wafer-like piezoelectric substrate (hereinafter, referred to as
"piezoelectric substrate wafer") for forming a SAW filter. However,
the processing target is not limited to the piezoelectric substrate
wafer. The bump-bonding heating apparatus of this embodiment is
applicable also to the charge-producing semiconductor substrate,
for example, compound semiconductor wafers of LiTaO.sub.3,
LiNbO.sub.3 or the like, quartz semiconductor wafers using a quartz
substrate, and the like. Further applicable are Si semiconductor
wafers using a Si substrate. In such a case, the Si wafer is heated
to about 250.degree. C.-about 270.degree. C. in a process of
forming the bumps.
[0059] The SAW (Surface Acoustic Wave) filter have been available
as a semiconductor device for transferring only signals of
specified frequencies. In recent years, however, due to increased
numbers of frequencies involved, there have been occurring not only
conventional cases, as shown in FIG. 22, where a device 250 is
formed along a direction perpendicular to a crystal orientation of
the wafer but also cases, as shown in FIG. 23, where a
semiconductor wafer 202 in which, for example, the SAW filter
devices 250 are formed along a skewed direction to the crystal
orientation and moreover bumps 251 are bonded on the devices 250 is
fabricated. When the bumps are formed on such the wafer in which
the device is formed along the skewed direction, there arises a
need of turning the wafer to an extent corresponding to an skewed
angle, which depends on a difference between the crystal
orientation and the skewed direction, in terms of the relation with
the movable direction of a bump-forming head. That is, there has
been arising a need of turning the wafer at higher accuracy, as
compared with the conventional case. The bump-bonding heating
apparatus, bump bonding method, and bump forming apparatus of this
embodiment are effective especially for semiconductor wafers that
need to be turned to the skew angle.
[0060] As shown in FIG. 1, a bump-bonding heating apparatus 110 of
this embodiment, roughly speaking, has a wafer turning member 111,
a turning unit 112, and a wafer heating unit 113. The wafer turning
member 111, on which the piezoelectric substrate wafer 201 prior to
a bump formation process in which bump bonding is performed
(hereinafter, referred to as "bump-unformed wafer") is mounted, is
turned circumferentially of the bump-unformed wafer 201 mounted on
the wafer turning member 111. Bumps are formed by a bump-forming
head 190 in electrode portions on the bump-unformed wafer 201
mounted on the wafer turning member 111 at the bump bonding
temperature, which is about 210.degree. C. in this embodiment.
Hereinafter, the piezoelectric substrate wafer after the bump
formation is referred to as "bump-formed wafer 202."
[0061] The wafer turning member 111 has a metallic, disc-shaped
wafer stage 1111 on which the bump-unformed wafer 201 is to be
mounted and which is larger in diameter than the bump-unformed
wafer 201, and a metallic, disc-shaped turntable 1112 which is
generally equal in size to the wafer stage 1111.
[0062] The turntable 1112, which is manufactured by tempering at a
temperature beyond the temperature of 210.degree. C., never
exhibits distortion when heated to about the temperature of
210.degree. C. The turntable 1112, on which the wafer stage 1111 is
to be mounted, has teeth 11127 formed over the entire circumference
of the turntable 1112 in this embodiment, the teeth 11127 being for
mesh with a later-described gear wheel 1122 provided in the turning
unit 112.
[0063] Also, as shown in FIG. 5, in a mounting surface 11121 of the
turntable 1112, on which the wafer stage 1111 is to be mounted, are
formed a first suction groove 11122 larger in diameter and a second
suction groove 11123 smaller in diameter, concentrically with each
other, The first suction groove 11122 and the second suction groove
11123 are communicated with each other by a communicating portion
11124. Further, the first suction groove 11122 and the second
suction groove 11123 communicate with a suction passage 11126
formed in the turntable 1112, and air in the first suction groove
11122 and the second suction groove 11123 as well as the suction
passage 11126 is sucked up by a suction unit 117 as described
later. Therefore, the wafer stage 1111 mounted on the mounting
surface 11121 can be sucked to the mounting surface 11121 by the
sucking operation of the suction unit 117. Also, by the first
suction groove 11122 and the second suction groove 11123 being
formed over the entire circumference of the turntable 1112, the
wafer stage 1111 can be sucked to the mounting surface 11121
uniformly over the entire circumference.
[0064] The reasons why a construction that the wafer stage 1111 is
held to the turntable 1112 by suction like this is adopted are as
follows. That is, since the wafer stage 1111 needs to be replaced
depending on thickness and size of the semiconductor wafer to be
processed, one reason is to facilitate this replacement operation.
Besides, whereas the turntable 1112 and the wafer stage 1111 are
heated to about 210.degree. C. in order to heat the bump-unformed
wafer 201 to the bump bonding temperature of about 210.degree. C.
in this embodiment, another reason is to permit thermal expansion
of the wafer stage 1111 caused by the heating process.
[0065] Further, on the mounting surface 11121 of the turntable
1112, two positioning pins 11125-1, 11125-2 are erectly provided
for positioning the wafer stage 1111 to be mounted on the mounting
surface 11121.
[0066] At a central portion of the turntable 1112 formed in the
above way, is attached a T-shaped joint 115 as shown in FIG. 2.
This joint 115 is composed of a disc-shaped fitting portion 1151
buried to the turntable 1112, and a passage forming portion 1152
erectly provided at the fitting portion 1151 and formed integrally
with the fitting portion 1151. With the joint 115 attached to the
turntable 1112, the passage forming portion 1152 protrudes beyond a
rear surface 11128 of the turntable 1112, extending through the
heating unit 113 in a rotatable state relative to the heating unit
113 having the turntable 1112 mounted on the heating unit 113, and
the passage forming portion 1152 is rotatably fitted to a
connecting member 116 at a connecting portion 1153 of the passage
forming portion 1152.
[0067] The connecting portion 1153 is fixed to a lift plate 120
which is moved up and down between a heating position 1191 and a
transfer position 1192 by a lifter unit 119 having, in this
embodiment, an air cylinder. The lifter unit 119 is attached to a
base plate 114 and controlled in operation by a control unit 180.
It is noted that the lift plate 120 is supported and guided for
up-and-down motion by two guide members 121.
[0068] When the joint 115 is attached to the turntable 1112, the
fitting portion 1151 of the joint 115 is buried in the turntable
1112 so that the mounting surface 11121 of the turntable 1112 and
one end surface 1151a of the joint 115 are positioned in the same
plane. In the state that the joint 115 is buried in the turntable
1112, within the joint 115 are provided a gas suction passage 1154
which communicates with the suction passage 11126 in the turntable
1112 and which extends within the passage forming portion 1152
along the passage forming portion 1152, and a suction blow passage
1155 which communicates with a gas inlet/outlet passage 11115
within the wafer stage 1111 and which extends within the passage
forming portion 1152 along the passage forming portion 1152.
[0069] The gas suction passage 1154 is connected to the suction
unit 117 via the connecting member 116. The suction unit 117 is
controlled in operation by the control unit 180. Air in the first
suction groove 11122 and the second suction groove 11123 is sucked
out by operation of the suction unit 117 via the gas suction
passage 1154 and the suction passage 11126. Also, the suction blow
passage 1155 is connected to a suction blow unit 118 via the
connecting member 116. The suction blow unit 118 is controlled in
operation by the control unit 180, and gas is sucked or blown
through gas inlet/outlet holes 11112 via the suction blow passage
1155 and the gas inlet/outlet passage 11115 by operation of the
suction blow unit 118.
[0070] The connecting member 116, and the connecting portion 1153
of the passage forming portion 1152 rotatably fitted to the
connecting member 116 as described above, are held airtight with a
seal structure using a seal member such as an O-ring. Therefore,
gas flowing through the gas suction passage 1154 and the suction
blow passage 1155 never leaks outside.
[0071] The wafer stage 1111 is manufactured by tempering at a
temperature beyond the temperature of 210.degree. C., so never
exhibiting warpage by heating to the temperature of about
210.degree. C. Therefore, the wafer stage 1111 can be held to the
turntable 1112 by suction as described above. Also, at the mounting
surface 11111 of the wafer stage 1111, on which the bump-unformed
wafer 201 is to be mounted, as shown in FIG. 4, are opened the gas
inlet/outlet holes 11112 for sucking and blowing the bump-unformed
wafer 201. Further at the mounting surface 11111, an escape groove
11113 into which holding claws 1412 of a wafer holding part 1411
holding the bump-unformed wafer 201 enter when the bump-unformed
wafer 201 is mounted onto the mounting surface 11111. Further,
provided at the mounting surface 11111 are two positioning rollers
11114 with which an orientation flat portion of the bump-unformed
wafer 201 mounted on the mounting surface 11111 makes contact, and
which are used for regulating the bump-unformed wafer 201. The gas
inlet/outlet holes 11112 communicate with the gas inlet/outlet
passage 11115 formed in the wafer stage 1111.
[0072] In a rear surface 11116 of the wafer stage 1111 confronting
the mounting surface 11111, are formed pin insertion holes 11117-1,
11117-2 in correspondence to the positioning pins 11125-1, 11125-2
erectly provided on the turntable 1112. The pin insertion hole
11117-1 has a cylindrical shape having such a hole diameter as to
fit to the positioning pin 11125-1, and the pin insertion hole
11117-2 has an elongated hole shape extending along a direction of
the diameter of the wafer stage 1111. This is intended to allow any
thermal expansion of the wafer stage 1111, which is caused by the
heating of the wafer stage 1111 to the temperature of about
210.degree. C., to be absorbed.
[0073] By the arrangements that the wafer stage 1111 is held by
suction to the turntable 1112 and that the pin insertion hole
11117-2 is elongated-hole shaped, as described above, the wafer
stage 1111 is allowed to freely stretch even when heated to the
temperature of about 210.degree. C., thus free from occurrence of
any deformations which would occur when the stretching is
restricted. Accordingly, the entire rear surface 11116 of the wafer
stage 1111 is permitted to make contact with the mounting surface
11121 of the turntable 1112, so that temperature of the wafer stage
1111 becomes generally uniform over the entire wafer stage 1111.
Therefore, the bump-unformed wafer 201 mounted on the wafer stage
1111 can be heated generally uniformly.
[0074] The wafer heating unit 113, on which the turntable 1112 is
mounted as described above, heats the bump-unformed wafer 201 to
the bump bonding temperature via the turntable 1112 and the wafer
stage 1111 of the wafer turning member 111. Also, as described
later, whereas the wafer turning member 111 is turned
circumferentially by the turning unit 112, the wafer heating unit
113 is inhibited from turning in the meantime.
[0075] The wafer heating unit 113, as shown in FIG. 6, has a
turntable mounting plate 1131 on which the turntable 1112 is to be
mounted, heaters 1132, and support members 1133. To the turntable
mounting plate 1131, as shown in FIG. 6, is connected a suction
device 11311 which is controlled in operation by the control unit
180, and the turntable 1112 mounted on the turntable mounting plate
1131 is held on the turntable mounting plate 1131 by suction
operation of the suction device 11311. The heaters 1132 are heaters
of cartridge type, in this embodiment, each of which is inserted
into a hole 1134 formed in the turntable mounting plate 1131 along
a direction perpendicular to the thicknesswise direction of the
turntable mounting plate 1131, and four heaters 1132 are arranged
in parallel to one another in this embodiment. The support members
1133 are members for supporting the turntable mounting plate 1131
onto the base plate 114 of the bump-bonding heating apparatus
110.
[0076] The turntable mounting plate 1131 is heated by the heating
of the heaters 1132, and heat of the turntable mounting plate 1131
is transferred to the turntable 1112 while part of the heat is
transferred also to the support members 1133. In this case, if the
support members 1133 are arranged so as to extend in the same
direction as an extended direction of the heaters 1132, heat of
heaters 1132 closer to the support members 1133 would be more
likely to be transferred to the support members 1133, as compared
with heat of heaters 1132 farther from the support members 1133.
Therefore, the turntable mounting plate 1131 would not become
generally uniform in temperature as a whole, causing a problem that
the turntable 1112 mounted on the turntable mounting plate 1131 and
besides the bump-unformed wafer 201 would not become generally
uniform in temperature as a whole. Moreover, it is difficult for
the heaters 1132 to produce heat generally uniformly over their
entire lengths at the beginning of heating, with the result that
the heaters 1132 would be lower in temperature at their both end
portions than at their central portions.
[0077] This being the case, in this embodiment, in order that heat
transfer from the heaters 1132 to the support members 1133 is not
biased and that the entire turntable mounting plate 1131 becomes
generally uniform in temperature as a whole, the support members
1133 are arranged so as to extend along a direction perpendicular
to the thicknesswise direction of the turntable mounting plate 1131
and the extended direction of the heaters 1132, and in
correspondence to the both end portions of the individual heaters
1132.
[0078] By such a constitution, heat is transferred from each of the
four heaters 1132 to the support members 1133, so that the whole
turntable mounting plate 1131 can be brought into a generally
uniform temperature, and that the whole bump-unformed wafer 201 can
be brought into a generally uniform temperature.
[0079] The turning unit 112 has a driving source 1121, a gear wheel
1122, and a rotational-force transmission mechanism 1123. The
driving source 1121 is implemented by a servomotor in this
embodiment and controlled in operation by the control unit 180. The
gear wheel 1122 is meshed with the teeth 11127 of the turntable
1112. The rotational-force transmission mechanism 1123 prevents the
heat of the turntable 1112 from transferring to the driving source
1121 and transmits driving force generated by the driving source
1121 to the gear wheel 1122 to thereby rotate the gear wheel 1122.
In this embodiment, a timing belt is used as the rotational-force
transmission mechanism 1123, but the mechanism is not limited to
this structure.
[0080] In the lift plate 120 that is moved up and down between the
heating position 1191 and the transfer position 1192 by the lifter
unit 119, as shown in FIGS. 9 to 11, four stays 123 are erectly
provided in correspondence to four places so as to be
circumferentially and equidistantly spaced from one another around
the turntable 1112. At a tip end of each stay 123, a guide roller
122 is rotatably supported to each stay 123. The guide roller 122
is to mesh with the teeth 11127 formed at the periphery of the
turntable 1112 and moves up and down the turntable 1112 between the
heating position 1191 and the transfer position 1192 in
correspondence to up and down movement of the lift plate 120.
[0081] As shown in FIG. 7, each guide roller 122 so structured that
a cylindrical body rotatably supported on the stay 123 by bearings
1225, and a lower flange 1221 and an upper flange 1222 protruding
diametrally of the cylindrical body at its lower and upper end
portions, are integrally formed, and that pins 1223 are provided
between the lower flange 1221 and the upper flange 1222 at
peripheral portions of the lower flange 1221 and the upper flange
1222. A pitch of the pins 1223 arranged along the peripheries of
the lower flange 1221 and the upper flange 1222 is equal to a pitch
of the teeth 11127 of the turntable 1112. Therefore, in response to
the rotation of the turntable 1112 by operation of the turning unit
112, each guide roller 122 also rotates.
[0082] Each guide roller 122 constructed as described above
prevents the turntable 1112 from shifting diametrally on the
turntable mounting plate 1131, and moves up and down the turntable
1112 as described above by the contact of the lower flange 1221
with the teeth 11127 of the turntable 1112.
[0083] With the aforementioned functions of the guide roller 122,
the guide roller 122 does not necessarily need to turn in
one-to-one correspondence together with the turntable 1112. So it
is also possible that, as shown in FIG. 8, a lower flange and the
teeth 11127 of the turntable 1112 are brought into contact with
each other without providing the pins 1223. With this structure,
however, since a guide roller may not rotate in one-to-one
correspondence with the turn of the turntable 1112, the result is
that the lower flange and the teeth 11127 rub more with each other
than in the case of the guide roller 122 of this embodiment.
Therefore, because of a higher likelihood of production of dust due
to wear, there arises a need of some additional countermeasure for
dust.
[0084] Although the guide roller 122 of this embodiment has less
generation of dust as described above, anticorrosion, heatproof
quenched steel is used for the lower flange 1221 so that the
generation of dust is further reduced.
[0085] Also, as shown in FIG. 12, when the turntable 1112 is
rotated by the gear wheel 1122 of the turning unit 112, the four
guide rollers 122 are so structured that each of two guide rollers
122-1 positioned farther from the gear wheel 1122 has no gap
generated between a root of the teeth 11127 of the turntable 1112
and the pin 1223 engaged with the root, and that, on the other
hand, each of two guide rollers 122-2 positioned closer to the gear
wheel 1122 has a gap generated between the root of the teeth 11127
of the turntable 1112 and the pin 1223. It is noted that in this
embodiment, the gaps 1226 are set each to 0.27 mm in the diametral
direction of the turntable 1112 at ordinary temperature.
[0086] Whereas the turntable 1112 is heated to about 210.degree. C.
as described above, provision of the gaps 1226 allows thermal
expansions of the turntable 1112 due to heat. This produces an
effect of preventing the turntable 1112 from deformation such as
warpage so that the turntable 1112 becomes generally uniform in
temperature as a whole, and therefore that the bump-unformed wafer
201 on the wafer stage 1111 becomes generally uniform in
temperature as a whole.
[0087] Further in the bump-bonding heating apparatus 110, a wafer
regulating unit 125 is provided, as shown in FIGS. 3 and 13, in
order to set the bump-unformed wafer 201 to a specified position on
the wafer stage 1111 when the bump-unformed wafer 201 is mounted
onto the wafer stage 1111. The wafer regulating unit 125 has two
regulating rollers 1252 making contact with a rim of the
bump-unformed wafer 201 placed on the wafer stage 1111, and a
driver part 1251 which moves the regulating rollers 1252
diametrally of the bump-unformed wafer 201 and which is controlled
in operation by the control unit 180.
[0088] The wafer regulating unit 125, with the bump-unformed wafer
201 floated from the wafer stage 1111, makes the regulating rollers
1252 moved diametrally by the driver part 1251, thereby making the
bump-unformed wafer 201 turn several times so that the orientation
flat of the bump-unformed wafer 201 takes after the positioning
rollers 11114 provided on the wafer stage 1111, whereby the
bump-unformed wafer 201 is positioned.
[0089] Further, in the bump-bonding heating apparatus 110, as shown
in FIG. 1, cover plates 124 are provided over the guide rollers
122. Due to the cover plates 124, even if the bump-unformed wafer
201 is broken when the wafer 201 is positioned by the wafer
regulating unit 125, the cover plates 124 prevent broken pieces of
the wafer 201 from entering to the teeth 11127 of the turntable
1112. For example in FIGS. 2, 3 and so on, representation of the
cover plates 124 is omitted.
[0090] The bump-bonding heating apparatus 110 described above can
be incorporated into a bump forming apparatus 101 for forming bumps
at electrodes in circuit portions on the bump-unformed wafer 201 as
shown in FIG. 3. It is noted that the bump forming apparatus 101 is
of the so-called two-magazine type that the apparatus includes both
a first container for containing therein piezoelectric substrate
wafers 201 prior to bump formation in a layered state, and a second
container for containing therein piezoelectric substrate wafers 202
after the bump formation in a layered state. However, the bump
forming apparatus 101 is not limited to this type, and may be
provided as the so-called one-magazine type that both the
piezoelectric substrate wafers 201 prior to bump formation and the
piezoelectric substrate wafers 202 after bump formation are
accommodated in one container.
[0091] The bump forming apparatus 101 has, roughly speaking, one
bump-bonding heating apparatus 110 as described above, one
bump-forming head 190, a carrier unit 130, transfer units 140
provided on carriage-in and -out sides respectively, lifter units
150 provided for the containers respectively, to lift those
respective containers, a pre-heater unit 160, a post-heater unit
170, and a control unit 180.
[0092] The bump-forming head 190 is a device for forming a bump at
the electrode of the bump-unformed wafer 201 mounted to the
bump-bonding heating apparatus 110 and heated to the bump bonding
temperature. The bump-forming head 190 has a wire feed portion 191
for feeding gold wire serving as a bump material, and besides a
bump forming portion for forming a ball by melting the gold wire
and then pressing the melting ball to the electrode, an ultrasonic
generator for making ultrasonic waves act on the bump at the time
of the pressing, and the like. The bump-forming head 190 as
constructed above is placed on an X-Y table 192 having, for
example, a ball screw structure and being movable in X- and
Y-directions perpendicular to each other on a plane. The
bump-forming head 190 is moved in the X- and Y-directions by the
X-Y table 192 so that the bump can be formed at each of the
electrodes of the bump-unformed wafer 201 placed and fixed on the
X-Y table 192.
[0093] The bump forming apparatus 101 is equipped with two kinds of
carrier units 130. A carriage-in unit 131, which is one of the
carrier units 130, is a device for extracting the bump-unformed
wafer 201 from the first container, and a carriage-out unit 132,
the other one, is a device for carrying the bump-formed wafer 202
after bump formation to the second container and accommodating the
wafer therein. The carriage-out unit 132 has the same structure and
operates in the same manner, as the carriage-in unit 131.
[0094] At a place where the carriage-in unit 131 is disposed, is
provided an orientation flat alignment unit 133 for orienting the
orientation flat of the bump-unformed wafer 201 taken out of the
first container 205 by the carriage-in unit 131 along a specified
direction.
[0095] The transfer units 140 is, in this bump forming apparatus
101, equipped with a carriage-in side transfer device 141 and a
carriage-out side transfer device 142. In the carriage-in side
transfer device 141, the bump-unformed wafer 201 held to a holding
base 1311 of the carriage-in unit 131 is clamped by the holding
part 1411 and carried to the pre-heater unit 160, and further
carried from the pre-heater unit 160 to the bump-bonding heating
apparatus 110. Meanwhile, in the carriage-out side transfer device
142, the bump-formed wafer 202 on the wafer stage 1111 of the
bump-bonding heating apparatus 110 is clamped by a wafer holding
portion 1421, and carried to the post-heater unit 170 and, further,
carried from the post-heater unit 170 to a holding base 1321 of the
carriage-out unit 132.
[0096] Each of the lifter units 150 is equipped with a first lifter
device 151 on which the first container is to be mounted, and a
second lifter device 152 on which the second container is to be
mounted. The first lifter device 151 lifts and lowers the first
container so that the bump-unformed wafer 201 is set to a position
where the bump-unformed wafer 201 can be taken out by the
carriage-in unit 131. The second lifter device 152 lifts and lowers
the second container so that the bump-formed wafer 202 held by the
carriage-out unit 132 can be accommodated to a specified position
within the second container.
[0097] In the pre-heater unit 160, the bump-unformed wafer 201
transferring from the carriage-in unit 131 and held by the holding
part 1411 is mounted on the pre-heater unit 160, and then the
pre-heater unit 160 increases the temperature of the bump-unformed
wafer 201 from room temperature to the bump bonding temperature of
about 210.degree. C., at which bump formation is performed, with
the bump-bonding heating apparatus 110.
[0098] In the post-heater unit 170, after the bump formation, the
bump-formed wafer 202 transferring from the bump-bonding heating
apparatus 110 and held by the wafer holding portion 1421 is mounted
on the post-heater unit 170, and then the post-heater unit 170
decreases gradually the temperature of the bump-formed wafer 202
from the bump bonding temperature of about 210.degree. C. to around
room temperature.
[0099] Although the bump forming apparatus of this embodiment has
been shown in a case where the pre-heater unit 160 and the
post-heater unit 170 are provided, it is also possible that
temperature increasing and decreasing operations from the
pre-heating operation to the post-heating operation are performed
by the bump-bonding heating apparatus 110 without providing the
pre-heater unit 160 and the post-heater unit 170.
[0100] Operation of the bump-bonding heating apparatus 110 provided
in the bump forming apparatus 101 as described above is explained
below. It is noted that the operation is controlled by the control
unit 180.
[0101] At a step (represented by "S" in the figure) 101 of FIG. 14,
as shown in FIG. 15, the bump-unformed wafer 201 held by the
holding part 1411 is carried from the pre-heater unit 160 into the
bump-bonding heating apparatus 110 as described above.
[0102] At the next step 102, suction operation by the suction
device 11311 that the turntable 1112 is sucked to the turntable
mounting plate 1131 provided in the heating unit 113 is halted.
Before the halt of the sucking operation, the turntable 1112 and
the wafer stage 1111 have already been increased in temperature to
about 210.degree. C. by the heating apparatus 110.
[0103] At the next step 103, the lifter unit 119 is operated so
that the lift plate 120 is lifted from the heating position 1191
toward the transfer position 1192. By this lifting operation, the
connecting member 116 fixed to the lift plate 120, and the guide
rollers 122 rotatably supported on the stays 123 erectly provided
on the lift plate 120 are lifted together concurrently. By the
guide rollers 122 being lifted, as shown in FIG. 11, the turntable
1112, on which the wafer stage 1111 is mounted, is lifted up to the
transfer position 1192 via the teeth 11127 making contact with the
lower flanges 1221 of the guide rollers 122. In addition, since the
joint 115 fixed to the turntable 1112 is also lifted along with the
turntable 1112, the connecting member 116 and the connecting
portion 1153 of the joint 115 are lifted integrally together
without exhibiting positional shifts in the up-and-down direction.
Further since lowering operation is similar to the lifting
operation, the connecting member 116 and the connecting portion
1153 of the joint 115 never exhibits positional shifts in the
up-and-down direction.
[0104] By the wafer stage 1111 having reached the transfer position
1192 at the step 103, the wafer stage 1111 comes into contact with
the bump-unformed wafer 201 held by the holding part 1411 at step
104 as shown in FIGS. 16 and 19, where the bump-unformed wafer 201
is received onto the wafer stage 1111 and mounted onto the wafer
stage 1111.
[0105] In this state, at step 105, a position-regulating operation
of the bump-unformed wafer 201 on the wafer stage 1111 is
performed. That is, as shown in FIG. 17, the holding claws 1412 of
the holding part 1411 are opened and then the bump-unformed wafer
201 is released from being held. Further the suction blow unit 118
operates so that a gas, which is clean air or nitrogen gas in this
embodiment, is jetted out through the gas inlet/outlet holes 11112
of the wafer stage 1111 via the suction blow passage 1155 and the
gas inlet/outlet passage 11115. In the blowing operation, since the
bump-unformed wafer 201 has been preheated, the jetted-out gas has
been heated to such a temperature as to hardly lower the
temperature of the bump-unformed wafer 201.
[0106] By the jet-out of the gas, the bump-unformed wafer 201 is
floated about 0.5 mm from the wafer stage 1111. While the
bump-unformed wafer 201 is floating, the regulating rollers 1252 of
the wafer regulating unit 125 are moved diametrally of the
bump-unformed wafer 201 by the driver part 1251 as shown in FIG. 20
and then come into contact with the rim of the bump-unformed wafer
201. And then the regulating rollers 1252 push forward the
bump-unformed wafer 201 until the orientation flat of the
bump-unformed wafer 201 makes contact with the positioning rollers
11114. Thus, the orientation flat of the bump-unformed wafer 201 is
regulated so that the orientation flat takes after the positioning
rollers 11114. By this operation, the positional regulation is
achieved.
[0107] After an end of this positional regulation operation, the
suction blow unit 118 halts the gas jet-out operation, starting a
suction operation. As a result, air is sucked through the gas
inlet/outlet holes 11112 by this suction operation, by which the
bump-unformed wafer 201 is sucked onto the wafer stage 1111.
[0108] At the next step 106, the driving source 1121 of the turning
unit 112 operates, by which the turntable 1112 is rotated to a
bonding angle by the gear wheel 1122 as shown in FIG. 21. It is
noted that the bonding angle refers to an angle as follows. That
is, since the bump-forming head 190 can be moved only in the X- and
Y-directions by the X-Y table 192, when the bumps are formed on a
wafer on which devices are formed in a skewed direction with
respect to the crystal orientation of the wafer, it is preferable
that either one direction of the X- and Y-directions and the skewed
direction are made coincident with each other, because a travel
amount of the X-Y table 192 becomes smaller, so that cycle time can
be reduced. Therefore, the bonding angle is a rotational angle of
the wafer for making one direction and the skewed direction
coincident with each other. The one direction is either one
direction of the X- and Y-directions, i.e., a crystal orientation
of a semiconductor wafer prior to the formation of circuit devices
or a direction perpendicular to a direction of the crystal
orientation.
[0109] Also, such bonding angles are stored in a storage part
within the control unit 180 according to types of the wafers to be
processed, and read out, as required, by the control unit 180.
Then, the control unit 180 controls the operation of the driving
source 1121 so that a turn corresponding to the bonding angle is
achieved.
[0110] In this embodiment, as described above, a servomotor is used
as the driving source 1121, and the turntable 1112 having the teeth
11127 for mesh with the gear wheel 1122 is turned by the gear wheel
1122 that is rotated by the servomotor. Therefore, the
bump-unformed wafer 201 can be turned with far higher accuracy, as
compared with the conventional gas floating type. Accordingly, even
if rotation corresponding to the bonding angle is required, the
bump-unformed wafer 201 can be rotated with high accuracy.
[0111] Since the gear wheel 1122 and the teeth 11127 are engaged
with each other, there would occur a turning-amount error due to a
backlash when the turning operation is performed. Therefore, this
embodiment also adopts a known error correcting method such as a
method of performing forward and reverse rotations.
[0112] At the next step 107, as shown in FIG. 18, the lifter unit
119 is operated so that the lift plate 120 is lowered from the
transfer position 1192 toward the heating position 1191. By this
lowering operation, the guide rollers 122 also lower, causing the
turntable 1112 to lower, so that the wafer stage 1111 on the
turntable 1112 is disposed to the heating position 1191. Then at
the next step 108, the suction device 11311 is operated again so
that the turntable 1112 is sucked to the turntable mounting plate
1131 of the heating apparatus 110. As a result of this, the
turntable 1112 is heated again to about 210.degree. C. to make up
for a degree to which the turntable 1112 has been cooled by the
foregoing lifting operation. Thus the bump-unformed wafer 201 is
heated to the bump bonding temperature. It is noted that the
bump-unformed wafer 201 has already been heated nearly to the bump
bonding temperature by the preheating operation.
[0113] Then, at the next step 109, bumps are formed on the
electrodes in circuit portions of the bump-unformed wafer 201 by
the bump-forming head 190. After this bump formation, at a step
110, the bump-formed wafer 202 is carried out from on the wafer
stage 1111 by the wafer holding portion 1421 of the carriage-out
side transfer device 142.
[0114] According to this embodiment, by the provision of the
bump-bonding heating apparatus 110, troublesome factors such as
needs of controlling the pressure, flow rate and the like of the
jetted-out gas depending on the size and weight of the
semiconductor wafer, as involved in the conventional gas floating
type, are eliminated, so that the bump forming apparatus becomes
easier to handle. Further, the bump-unformed wafer 201 can be
rotated with far higher accuracy, as compared with the conventional
gas floating type, so that the bump-unformed wafer 201, even if
required to be turned to an extent of the bonding angle, can be
rotated with high accuracy. Furthermore, the heating apparatus 110
for heating the turntable 1112 and so on is not rotated, a compact
apparatus configuration can be obtained.
[0115] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications are apparent to those skilled in the art. Such
changes and modifications are to be understood as included within
the scope of the present invention as defined by the appended
claims unless they depart therefrom.
* * * * *