U.S. patent application number 10/335364 was filed with the patent office on 2004-07-01 for wafer electroplating apparatus and method.
Invention is credited to Chiang, Pang-Min, Du, Chen-Chung, Huang, Jen-Rong, Wang, Chih-Cheng.
Application Number | 20040124090 10/335364 |
Document ID | / |
Family ID | 32655332 |
Filed Date | 2004-07-01 |
United States Patent
Application |
20040124090 |
Kind Code |
A1 |
Du, Chen-Chung ; et
al. |
July 1, 2004 |
Wafer electroplating apparatus and method
Abstract
A wafer electroplating apparatus and method, comprising a wafer
turning assembly, a vertical movement assembly, a wafer tilting
assembly, and a frame. The wafer turning assembly has a turning
shaft and a clasp for holding a wafer. The wafer tilting assembly
has a tilting table being driven by a driving system, e.g. a
cylinder, carrying an electroplating unit and wafer turning
assembly. Thus the clasp holding a wafer and the electroplating
unit are simultaneously inclined at preset angle against the
horizontal plane, allowing for a large inclination angle.
Therefore, gas bubbles generated during electroplating readily
escape, and quality of electroplating is improved.
Inventors: |
Du, Chen-Chung; (Hsinchu,
TW) ; Chiang, Pang-Min; (Taipei, TW) ; Wang,
Chih-Cheng; (Taichung, TW) ; Huang, Jen-Rong;
(Hsinchu, TW) |
Correspondence
Address: |
PRO-TECHTOR INTERNATIONAL
20775 Norada Court
Saratoga
CA
95070-3018
US
|
Family ID: |
32655332 |
Appl. No.: |
10/335364 |
Filed: |
December 30, 2002 |
Current U.S.
Class: |
205/137 ;
204/199; 205/146; 257/E21.175 |
Current CPC
Class: |
C25D 17/00 20130101;
H01L 21/2885 20130101 |
Class at
Publication: |
205/137 ;
205/146; 204/199 |
International
Class: |
C25D 005/00; C25D
017/00 |
Claims
1. A wafer electroplating method, comprising the steps of: A.
inserting a wafer into a clasp; B. holding said wafer in said
clasp; C. lowering said wafer to a location of electroplating; D.
inclining of a tilting table to incline said wafer; E. slowly
turning said wafer and electroplating; F. completing of
electroplating; G. raising said wafer from said location of
electroplating; H. reversing inclination of said tilting table; I.
fast turning of said wafer for drying; J. stopping of said wafer;
K. opening said clasp; and L. removing said wafer.
2. A wafer electroplating apparatus, comprising: a frame, having a
main body, on which a piping system and a control unit are
installed; a wafer turning assembly, having a casing and a lower
end, to which a clasp for holding a wafer is attached; a vertical
movement assembly, mounted on a side of said wafer turning
assembly, having a vertical column, on which a vertical driving
device is installed, driving said wafer turning device in a
vertical movement; and a wafer tilting assembly, having two seats,
which are fastened on two opposite sides of said main body, with a
tilting table inserted between and held by said two seats, said
tilting table being inclined at a tilting angle, as driven by a
driving system via a connecting rod, said tilting table carrying
said vertical shifting assembly and an electroplating unit; wherein
a suitable value of said tilting angle is set using said driving
system, with said clasp and said electroplating unit being
simultaneously tilted and, by tilting to any angles, the clearance
between the two is kept constant, thereby not hindering fluid
patent be changed. The tilting angle of the wafer can be tilted to
a larger angles. Gas bubbles generated during electroplating of
said wafer is readily to escape from surface.
3. The wafer electroplating apparatus according to claim 2, wherein
said wafer turning assembly further comprises a gas inlet, a
turning shaft, electrical connectors and a driving unit, with a gas
pressure cylinder being installed inside said turning shaft,
holding said clasp.
4. The wafer electroplating apparatus according to claim 2, wherein
said clasp has a cathode at a suitable position and a liquid
blocking ring.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a wafer electroplating
apparatus and method, particularly to a wafer electroplating
apparatus and method having a wafer-holding clasp and an
electroplating unit that are mounted on a common tilting table,
being simultaneously tilted, so that larger tilting angle can be
adjusted for and gas bubbles generated during electroplating escape
readily.
[0003] 2. Description of Related Art
[0004] When performing conventional fountain-type electroplating of
a wafer, the wafer is rotated to ensure uniform electroplating. The
main difference to bath type electroplating is that a clasp holding
the wafer is not completely immersed in a bath, establishing dry
contact.
[0005] In fountain-type electroplating, a wafer is laid onto a
electroplating tank. During the ensuing chemical reaction, gas
bubbles are produced, which readily stick to a electroplating
surface of the wafer, causing the chemical reaction locally to
stop, so that incomplete electroplating results. To avoid this
shortcoming, the wafer is inclined, allowing gas bubbles to escape
easily.
[0006] Inclining of the wafer is done by turning the clasp holding
the wafer by an inclination angle, so that the wafer and a fixed
electroplating tank inclined against each other. This results in
the wafer, e.g. a 12 inch wafer, having an increased inclined
diameter and the clasp being immersed in the eletroplating solntion
at an edge thereof. To avoid contamination of the clasp at a rear
side thereof, the inclination angle is only chosen to be 1-2
degrees. However, a small inclination angle results in insufficient
clearing of gas bubbles. On the other hand, when being turned, the
clasp is partially exposed in succession to air and electroplating
solution of the tank, which easily leads to external air bubbles
entering the electroplating solution in the tank and impairing the
chemical reaction, so that electroplating is defective.
[0007] Fountain-type electroplating requires a suitable gap between
the wafer and the top of tank. Thus pressure of the electroplatong
solution in the tank is maintained while liquid flows out through
the electroplating tank, so that liquid completely and uniformly
covers the wafer. For maintaining pressure of the electroplating
solution, the cross-section area of the gap is required to be
smaller than the cross-section area of an inlet of the tank,
resulting in an outflow velocity of liquid that is larger than an
inflow velocity thereof and in uniform flow through the gap.
[0008] While fountain-type electroplating allows for electroplating
with uniform thickness, pockets of imperfect electroplating occur
easily due to gas bubbles. In order to allow gas bubbles readily to
escape, the wafer is inclined. This not only creates an external
disturbance, but also due to an inclined orientation of the wafer
and buoyancy leads to the gas bubble movement.
[0009] In conventional art, the electroplating tank is fixed, only
the wafer is inclined against a horizontal plane. Since the
cross-section area of the gap between the wafer and the tank is
nonuniform, pressure is not maintained easily, the clasp is in
turns exposed to air and liquid, resulting in external air bubbles
enturing to the tank that adversely affect the chemical reaction.
Furthermore, inclination of the wafer is restricted to 1-2 degrees,
as described in U.S. Pat. No. 6,080,291, resulting in ineffective
clearing of gas bubbles.
[0010] Moreover, the apparatuses disclosed in U.S. Pat. No.
6,080,291 and No. 6,334,937 have the following shortcomings:
[0011] 1. When the wafer is inclined, with the tank unmoving, not
only the cross-section area between the wafer and the tank
nonuniform, but also the permissible inclination angle is
reduced.
[0012] 2. The clasp has no liquid blocking ring. When being held,
the wafer at the rear side thereof is easily contaminated.
[0013] 3. Using a robot to incline the wafer requires a higher
cost.
[0014] 4. No sealing device for the electroplating area is
provided, so leaking of gas generated in the bath is not
effectively prevented.
SUMMARY OF THE INVENTION
[0015] The main object of the present invention is to provide a
wafer electroplating apparatus which allows to set large
inclination angle, so that gas bubbles escape easily, and which
comprises a wafer turning assembly, a vertical movement assembly, a
wafer tilting assembly, and a frame, with the wafer turning
assembly having a clasp and a turning shaft and the wafer tilting
assembly having an electroplating unit set on a tilting table
driven by a driving system, e.g., a gas pressure cylinder, so that
a mounted wafer and the electroplating unit are simultaneously
inclined at any preset angle.
[0016] Another object of the present invention is to provide a
wafer electroplating apparatus which avoids contamination of the
mounted wafer at a rear side thereof by adding a protective ring to
the clasp for keeping liquid of an electroplating tank from
reaching the rear side of the wafer.
[0017] A further object of the present invention is to provide a
wafer electroplating apparatus which prevents gas from leaking to
the outside when the wafer is tilted by having a dome set on the
wafer turning assembly, keeping the wafer turning assembly sealed
during vertical movements thereof.
[0018] A further object of the present invention is to provide a
wafer electroplating method in which the wafer turning assembly
with the clasp and the electroplating unit, set on the tilting
table driven by the driving system, are simultaneously tilted, so
that adjusting a mounted wafer at larger inclination angle against
the horizontal plane is possible, allowing gas bubbles generated
during electroplating easily to escape.
[0019] The present invention can be more fully understood by
reference to the following description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of the wafer electroplating
apparatus of the present invention.
[0021] FIG. 2 is a front view of the wafer electroplating apparatus
of the present invention.
[0022] FIG. 3 is a side view from the right of the wafer
electroplating apparatus of the present invention.
[0023] FIG. 4 is a top view of the wafer electroplating apparatus
of the present invention.
[0024] FIG. 5 is a sectional view of the wafer electroplating
apparatus of the present invention.
[0025] FIG. 6 is an enlarged sectional view of the clasp of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] As shown in FIGS. 1-4, the wafer electroplating apparatus of
the present invention mainly comprises: a frame 10; a wafer turning
assembly 20; a vertical movement assembly 30; and a wafer tilting
assembly 40.
[0027] The frame 10 has a main body for stable mounting of other
components and four lower corners to each of which a wheel 111 and
an adjustable support 112 are attached, allowing either to move or
to fix the frame 10. The frame 10 carries a pipe unit and a control
unit.
[0028] The wafer turning assembly 20 has a casing 21. Inside the
casing 21, the wafer turning assembly 20 further has a gas inlet
22, a turning shaft 23, electrical connectors 24 and a driving unit
241. A motor and a conveyor belt in the driving unit 241 drive a
rotating movement of the turning shaft 23. On a lower end of the
wafer turning assembly 20, a clasp 25 is provided for holding a
wafer, being in turn connected with a gas pressure cylinder 26
inside the turning shaft 23. A dome 27 is set on the casing 21,
covering the casing 21 tightly during electroplating process and
preventing gas from leaking to the outside as well as air entering
the inside of the casing 21.
[0029] The vertical movement assembly 30 has a vertical column 31
set on a tilting table 42. A movement unit 32 with ball bearings
and a servomotor 33 drive a vertical movement of the wafer turning
assembly 20, as in conventional art.
[0030] The wafer tilting assembly 40 is mounted on the main body
11, having a horizontal shaft 411 held in two seats 41 on two
opposite sides of the main body 11. The tilting table 42 is
inserted between the seats 41, turning with the horizontal shaft
411, with a lock 412 on the seat 41 fixing the tilting table 42 a
tilting angle. A connecting rod 421 hingedly connects the tilting
table 42 with a gas pressure rod of a gas pressure cylinder 43. The
gas pressure cylinder 43 has a fixed end connected with the main
body 11. The tilting table 42 carries an electroplating tank unit
44. The electroplating tank unit 44 contains an electroplating
solution and has an electroplating tank 441 serving as an anode.
The electroplating tank 441 has a overflow tank 442, collecting
liquid overflowing from the electroplating tank 441. The overflow
tank 442 is covered by the dome 27.
[0031] The gas pressure cylinder 43, via the gas pressure rod
thereof, drives the tilting movement of the tilting table 42
towards a suitable tilting angle. Since the electroplating tank 441
and the clasp 25 participate simultaneously in the tilting
movement, the gap remain unchanged. Thus adjusting for a large
tilting angle is possible, allowing the bubble generated during
electroplating of the wafer easily to escape, improving quality of
electroplating.
[0032] Referring to FIG. 6, the clasp 25 has an upper part 251 and
a lower part 252 effectively holding the wafer. An cathode 253 is
placed in a suitable position, and a liquid blocking ring 254 is
laid around a periphery of the clasp, preventing the electroplating
solution from contaminating the wafer at a rear side thereof when a
tilting angle is assumed.
[0033] The wafer electroplating method of the present invention
comprises simultaneous tilting of the turning shaft 23 with the
clasp 25 and the electroplating unit, set on the tilting table 42
that is connected with the horizontal connecting rod 411 and driven
by a driving system (in the embodiment shown, the gas pressure
cylinder 43). Thus adjusting a mounted wafer at larger inclination
angle against the horizontal plane is possible, allowing the
bubbles generated during electroplating easily to escape.
[0034] For better understanding, the steps of the wafer
electroplating method of the present invention are given as
follows:
[0035] A. Inserting the wafer into the clasp; B. holding the wafer
in the clasp; C. lowering into the location of electroplating; D.
inclining of the tilting table to incline the wafer; E. slowly
turning the wafer and electroplating; F. completing of
electroplating; G. raising from the location of electroplating; H.
reversing inclination of the tilting table; I. fast turning of the
wafer for drying; J. stopping of the wafer; K. opening the clasp;
L. removing the wafer.
[0036] As the above explanation shows, the present invention offers
the following advantages:
[0037] (1) A large tilting angle (over 45 degrees) is possible,
allowing the gas bubbles generated during electroplating readily to
escape.
[0038] (2) The tilting angle is freely adjustable, increasing
flexibility.
[0039] (3) The clasp is not in turns exposed to air and liquid, so
that no gas bubbles hindering chemical reactions enter the
electroplating tank.
[0040] (4) Different designs of the clasp for larger wafer are not
required, simplifying the assembly.
[0041] (5) Electroplating is performed in an unchanging electric
field, any variation of the tilting angle does not alter the
geometry of cathode, anode and the wafer.
[0042] The wafer electroplating apparatus and method of the present
invention provides for a wafer-holding clasp and an electroplating
unit that are mounted on a common tilting table, being
simultaneously tilted, so that larger tilting angle is adjustable
for and gas bubbles generated during electroplating escape readily.
Thus an improved electroplating apparatus and method are provided,
providing for various practical functions.
[0043] While the invention has been described with reference to
preferred embodiments thereof, it is to be understood that
modifications or variations may be easily made without departing
from the spirit of this invention which is defined by the appended
claims.
* * * * *