U.S. patent application number 14/553840 was filed with the patent office on 2015-03-19 for electroplating processor with geometric electrolyte flow path.
The applicant listed for this patent is APPLIED Materials, Inc.. Invention is credited to Randy A. Harris, Paul R. McHugh, Jeffrey I. Turner, Gregory J. Wilson, Daniel J. Woodruff.
Application Number | 20150075976 14/553840 |
Document ID | / |
Family ID | 49547798 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150075976 |
Kind Code |
A1 |
Harris; Randy A. ; et
al. |
March 19, 2015 |
ELECTROPLATING PROCESSOR WITH GEOMETRIC ELECTROLYTE FLOW PATH
Abstract
An electroplating processor includes an electrode plate having a
continuous flow path formed in a channel. The flow path may
optionally be a coiled flow path. One or more electrodes are
positioned in the channel. A membrane plate is attached to the
electrode plate with a membrane in between them. Electrolyte moves
through the flow path at a high velocity, preventing bubbles from
sticking to the bottom surface of membrane. Any bubbles in the flow
path are entrained in the fast moving electrolyte and carried away
from the membrane. The electroplating processor may alternatively
have a wire electrode extending through a tubular membrane formed
into a coil or other shape, optionally including shapes having
straight segments.
Inventors: |
Harris; Randy A.;
(Kalispell, MT) ; Woodruff; Daniel J.; (Kalispell,
MT) ; Turner; Jeffrey I.; (Kalispell, MT) ;
Wilson; Gregory J.; (Kalispell, MT) ; McHugh; Paul
R.; (Kalispell, MT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
APPLIED Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
49547798 |
Appl. No.: |
14/553840 |
Filed: |
November 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13468273 |
May 10, 2012 |
|
|
|
14553840 |
|
|
|
|
Current U.S.
Class: |
204/263 ;
204/252 |
Current CPC
Class: |
C25D 17/12 20130101;
C25D 17/002 20130101; C25D 7/123 20130101; C25D 17/001
20130101 |
Class at
Publication: |
204/263 ;
204/252 |
International
Class: |
C25D 17/12 20060101
C25D017/12; C25D 17/00 20060101 C25D017/00 |
Claims
1. An electroplating processor, comprising: a vessel; a tubular
membrane in the vessel extending between an inlet and an outlet;
and an electrode wire extending through the tubular membrane.
2. The electroplating processor of claim 1 with the tubular
membrane having rings formed between a coiled channel wall.
3. The electroplating processor of claim 1 with the tubular
membrane comprising a spiral.
4. The electroplating processor of claim 1 further including a head
engageable with the vessel, and with no element between the head
and the tubular membrane so that an open space is provided between
the tubular membrane and the head.
5. The electroplating processor of claim 1 further comprising a
membrane plate having a channel, and with the tubular membrane in
the channel.
6. The electroplating processor of claim 5 with the channel having
a rectangular cross section and the tubular membrane having a round
cross section.
7. The electroplating processor of claim 1 wherein the tubular
membrane is a spiral or concentric circles connected by flow
segments.
8. The electroplating processor of claim 1 wherein the cross
section of the tubular membrane adjacent to the outlet is greater
than at the inlet.
9. The electroplating processor of claim 5 wherein the membrane
plate has one or more rings of ribs, and with the coiled support
attached to a bottom surface of the ribs.
10. An electroplating processor, comprising: a vessel; a head
engageable with the vessel; a cathode on the head; a tubular
membrane in the vessel extending between an inlet and an outlet;
and an anode in the tubular membrane.
11. The electroplating processor of claim 10 further including a
vessel membrane separating an anolyte chamber from a catholyte
chamber within the vessel, and with the tubular membrane in the
catholyte chamber.
12. The electroplating processor of claim 10 with the tubular
membrane comprising a spiral.
13. The electroplating processor of claim 11 further including a
catholyte drain in the catholyte chamber below the tubular
membrane.
14. The electroplating processor of claim 10 further comprising a
membrane plate having a channel, and with the tubular membrane in
the channel.
15. An electroplating processor, comprising: a vessel; a tubular
membrane in the vessel between forming a continuous flow path
between an inlet and an outlet; and an electrode wire in the
tubular membrane.
16. The processor of claim 15 with electrode wire connected to an
anode, and a cathode above the tubular membrane.
Description
PRIORITY CLAIM
[0001] This Application is a Divisional of U.S. patent application
Ser. No. 13/468,273, filed May 10, 2012, now pending and
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The field of the invention is chambers, systems, and methods
for electrochemically processing semiconductor material wafers and
similar substrates having micro-scale devices integrated in and/or
on the work piece.
BACKGROUND OF THE INVENTION
[0003] Microelectronic devices are generally fabricated on and/or
in wafers or similar substrates. In a typical fabrication process,
an electroplating processor applies one or more layers of
conductive materials, typically a metals, onto the substrate. The
substrate is then typically subject to etching and/or polishing
procedures (e.g., planarization) to remove a portion of the
deposited conductive layers, to form contacts and/or conductive
lines. Plating in packaging applications may be performed through a
photoresist or similar type of mask. After plating, the mask may be
removed, with the metal then reflowed to produce bumps,
redistribution layers, studs, or other interconnect features.
[0004] Many electroplating processors have a membrane separating
anolyte plating liquid from a catholyte plating liquid within a
bowl or vessel. In these processors, bubbles in the plating liquid
may collect and stick to the bottom surface membrane. The bubbles
act as an insulator, disrupting the electric field in the
processor, and leading to inconsistent plating results on the work
piece. Accordingly, engineering challenges remain in designing
electroplating processors providing consistent plating results.
SUMMARY OF THE INVENTION
[0005] A new electroplating processor has now been invented that
largely overcomes bubble-related variations in electroplating. This
new electroplating processor includes an electrode tray or plate
having a continuous flow path formed in a channel. The flow path
may optionally be coiled. One or more electrodes are positioned in
the channel, or multiple separate flow channels may be provided
with a separate electrode in each channel. A membrane plate is
attached to the electrode plate with a membrane in between them.
Electrolyte moves through the flow path at a high velocity,
preventing bubbles from sticking to the bottom surface of membrane.
Any bubbles in the flow path are entrained in the fast moving
electrolyte and carried away from the membrane. In an alternative
design, a metal electrode, such as a platinum wire, may be
positioned inside of a tubular membrane, with electrolyte flowing
through the tubular membrane. The flow channels may be curved, or
provided with straight segments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In the drawings, the same element number indicates the same
element in each of the views.
[0007] FIG. 1 is a perspective view of a new electroplating
processor.
[0008] FIG. 2 is a perspective view of the processor of FIG. 1 with
the head removed, for purpose of illustration.
[0009] FIG. 3 is a section view through the vessel of the processor
shown in FIGS. 1 and 2.
[0010] FIG. 4 is another section view through the vessel of the
processor shown in FIGS. 1 and 2.
[0011] FIG. 5 is a top perspective view of the channel plate shown
in FIGS. 3 and 4.
[0012] FIG. 6 is a top perspective view of the membrane plate shown
in FIGS. 3 and 4.
[0013] FIG. 7 is a top perspective view of an alternative design
using a membrane tube.
[0014] FIG. 8 is a top perspective view of an alternative design
having an electrolyte flow channel formed as a linear array.
DETAILED DESCRIPTION
[0015] Turning now to the drawings, as shown in FIGS. 1 and 2, an
electroplating processor includes a head 14 and a base 12. A head
lifter 16 lifts and lowers the head to move a work piece held in
the head into a vessel or bowl 18 in the base. The vessel holds
electroplating liquid. An agitator plate 24 may optionally be
provided near the top of the vessel 18 to agitate the
electroplating liquid adjacent to the work piece.
[0016] Referring now also to FIGS. 3 and 4, the vessel 18 may be
divided via a membrane 32 into upper and lower chambers. A channel
plate 30 is provided at the bottom of the vessel 18. The channel
plate is typically an insulator, such as plastic. A channel 42 may
be provided in the channel plate 30, with an anode material 52 in
the channel 42. Alternatively, the channel plate 30 may be metal,
such as platinum plated titanium, with a flow channel machined into
the metal plate. The membrane 32 is clamped between the channel
plate 30 on the bottom and a membrane plate 60 on top. As shown in
FIGS. 4 and 5, a circular or coiled flow path 40 is formed in the
top surface of the channel plate 30. Specifically, the coiled flow
path 40 is formed via a coiled channel, groove or slot 42 in the
channel plate, and by a corresponding coiled wall 44 which
separates adjacent rings of the flow path 40.
[0017] The flow path 40 may be continuous and extend uninterrupted
from an inlet 36 adjacent to an outer edge of the channel plate 30,
to a drain 35 at or near the center of the channel plate, as shown
in FIG. 5. Generally, the clamping force on the membrane 32 is
highest adjacent to outside of the channel plate 30, closer to the
fasteners or bolts clamping the channel plate and the membrane
plate 60 against the membrane 32. Since the fluid pressure in the
flow path 40 is highest at the inlet, in some designs locating the
inlet towards the outside of the channel plate 30, closer to the
fasteners, may provide a better seal against the membrane. In other
designs, the inlet and outlet positions may optionally be switched,
with the inlet adjacent to an outer edge of the channel plate 30.
An alternative to the face-to-face seal shown in FIG. 4 is to
install a long circular elastomer that seals the membrane to the
anode surface.
[0018] The membrane plate 60 is designed as a relatively stiff
structure so that it is not deflected or deformed by the fluid
pressure under the membrane that is required to pump the anolyte
through the spiral flow path. Upward deflection of the membrane
plate 60 would create leak paths over the spiral walls and
underneath the membrane that would short circuit the spiral flow
path. While some fluid leakage over the wall is tolerable (i.e. a
perfect seal is not required), excessive flow over the walls
decreases the flow velocity in the spiral path and reduces the
ability to entrain and carry away bubbles.
[0019] In the design shown in FIG. 5, the channel 42 has a
rectangular cross section, with the height of the channel greater
than the width of the channel. For example, the height of the
channel may be twice the width of the channel 42. Other channel
shapes, such as square and curved cross section channels may also
be used. The cross section of the channel 42 may also vary between
the inlet and outlet. The wall thickness of the channel wall 44 may
also vary between the rings.
[0020] Referring still to FIG. 5, the coiled flow path 40 may be a
true spiral in a mathematical sense, or other variations of a
spiral. In FIG. 5, the rings of the flow path are circular, with a
straight segment 46 providing the offset to have each ring of the
flow path transition into adjacent rings. Similarly, the flow path
may also have other shapes such as oval, elliptical, etc. The flow
path 40 may also simply formed via concentric circles, or more
properly circular or curved annular channels, connected by segments
of any shape. Accordingly, the terms coil or coiled are used here
to collectively include spirals and any other pathways having
progressively expanding rings, regardless of their shape.
[0021] In FIG. 5, the rings are labeled 1-9. For a processor
designed to electroplate a 300 mm diameter work piece, the flow
path may have 5-15 or 7-12 rings. Processors designed to
electroplate a 450 mm diameter work piece may have proportionally
more rings, i.e., 7-22 rings or 10-18 rings. The flow path 40 shown
in FIG. 5 having 9 rings may have a total length of about 3-6 or
4-5 meters. In selecting the number or rings and the total length
of the flow path 40, as well as the cross section(s) of the channel
42, the pressure required to move anolyte through the flow path may
be a limiting factor.
[0022] The channel wall 44 in the example shown has a generally
flat top. A corresponding coiled plate support 62 on the bottom
surface of the membrane plate 60, shown in FIG. 6, may match the
shape and position of the channel wall 44. When the membrane plate
60 is clamped to the channel plate 30, with the membrane 32 between
them, the top surface of the channel wall 44 aligns with bottom
surface of the coiled plate support, with the membrane clamped
between them. The coiled plate support 62 may be a mirror image of
the channel wall 44, although they do not necessarily have the same
height.
[0023] As shown in FIGS. 3 and 4, an inner or first anode 50 is
positioned on the floor of the channel 42 in the inner rings of the
flow path 40. A second or outer anode 52 is positioned on the floor
of the channel 42 in the outer rings of the flow path 42. As shown
in FIG. 5, a first electrical contact 54 connects to the first
anode 50 and a second electrical contact 56 separately connects to
the second anode 52. The first and second anodes do not connect to
each other. However, they are electrically connected through the
electrolyte, so that they are not fully electrically isolated from
each other. A small gap may be provided between them. On the other
hand, both the first and second anodes are in the single continuous
flow path 40. While two anodes are shown, in some designs a single
anode may be used, or three or more anodes may be used.
[0024] The electrical contact for each anode may be approximately
centered on its length to help insure uniform electric current
along the anode. For a long, thin anode spiral connected at one
end, the current density along the anode may drop moving away from
the contact because of the electrical resistance of the anode,
itself. For very thin and/or very long electrodes, multiple
connections can be made to each anode to help distribute the
current uniformly.
[0025] The anodes 50 and 52 may be provided as flat strips of
metal. In an inert anode design, where the anodes are not consumed
during electroplating, the anodes may be platinum plated titanium.
Alternatively, in an active anode design, where the anode is
consumed, the anodes may be copper, or other metals.
[0026] Referring to FIG. 6, the membrane plate 60 may have an outer
ring of ribs 64, and inner ring of ribs 66, and a center ring 68.
The coiled membrane support 62 on the bottom surface of the
membrane plate 60 may be attached to ribs. Alternatively, the
coiled membrane support 62 may be integrally formed as part of the
membrane plate, along with ribs and other features of the membrane
plate 60. The rings of ribs provide a membrane plate 60 having a
largely open cross section, to minimize affecting the electric
field in the vessel, while also providing a rigid structure to
clamp and seal against the membrane. The membrane plate and the
channel plate are generally a di-electric material, such as
polypropylene or other plastic. The membrane plate 60 may have
catholyte inlets 70 and 72 in inner and outer annular sidewalls, to
introduce catholyte into the vessel at a position immediately above
the membrane 32.
[0027] The rings of ribs 66 can have special provision for helping
to minimize disturbances to the electric field that may be
detrimental to plating uniformity. For example the vertical height
of the center post and inner-most ribs maybe reduced to create a
larger gap between the structure and the workpiece. The center
region can be particularly influenced by the structure because
wafer spinning does not help average out disturbances in this
region. In another example, the circular ribs may be made as thin
as possible, or made thinner at the top of the structure to help
minimize their disturbance of the electric field, since their
influence on the wafer also cannot be averaged out by wafer
rotation.
[0028] In conventional electroplating membrane processors, the
anolyte, or other electrolyte, moves slowly along the membrane.
This allows gas bubbles to stick to the membrane and degrading
plating performance, especially with substantially horizontally
oriented membranes. Using an inert anode tends to generate
substantial amounts of gas bubbles, as a electrolysis reaction
occurs at the surface of the inert anode releasing oxygen gas.
[0029] Gas evolution from the anode can be especially problematic
for processes that have a high plating rate (and therefore a high
anode current and large gas creation) necessary so that the process
can finish quickly and throughout can be maximized."
[0030] In the processor 10 having a circular flow path 40 anolyte
is pumped to the inlet at sufficient pressure so that it moves
through the flow path at a high velocity. The velocity of the
anolyte flowing through the channel is sufficient to prevent
bubbles from sticking to the bottom surface of membrane 32. Rather,
the bubbles are entrained in the fast moving liquid and cannot
stick or collect on the membrane. Therefore, bubbles created by the
process are quickly carried out of the chamber preventing them from
partially or completely blocking the electrical flow path between
the anode and the cathode, helping to provide a reliable
process.
[0031] As shown in FIG. 7, alternative design is to use a membrane
tube 80 with a wire 82 inside the tube as the anode material.
Optionally multiple membrane tubes 80 may be used. The membrane
tube 80 may be in a coil or other shape. This approach avoids the
need for the membrane plate 60 because there is no need to clamp a
planar membrane. The chamber can then be more open to for
electrical current flow. This approach also avoids the risk of flow
leaking between adjacent channels. Rather, the flow is confined to
within the membrane tube and is forced to follow the path of the
tube. The design of FIG. 7 may also enable more efficient draining
of the catholyte chamber because there is flat divider between the
anolyte and catholyte. The tubes can reside within the catholyte
and so catholyte can be drained from a low spot below the elevation
of the membrane tubes.
[0032] For the case of a constant area channel, the spiral flow
path created by the clamping the membrane to the divider walls 44
can be thought of as similar to the flow within a spiraled tube.
For a constant area channel, the flow velocity in the channel and
over the anode and the membrane is constant and high throughout its
entire length. In contrast, with existing conventional processors,
the anolyte flow might be high near the flow inlet, but the
velocity dissipates as the flow is distributed over the volume of
the anode compartments making it difficult to use the flow to help
sweep away bubbles.
[0033] The coiled electrolyte path of FIGS. 1-6 may be used in
various types of electroplating processors, other than the
processor shown in FIGS. 1 and 2. Specifically, it may be used in
any electroplating processor having a vessel and a membrane. Where
the membrane tube of FIG. 7 is used, no other separate membrane is
needed.
[0034] The electrolyte flow channel need not be a spiral, have
concentric rings, or even include largely curved shapes. Rather, as
shown in FIG. 8, the channel 42 may have an array or other
arrangement of straight segments 84. As one example, the channel
may be formed as an array of progressively larger quadrilateral or
other geometric shapes, generally matching the shape of the
substrate. If desired, curved transition sections may be used at
the ends of the straight segments 84, to reduce pressure loss
through the channel. Similar designs using straight segments may
also be used with the membrane tube as described above.
[0035] A method for electroplating a workpiece may include pumping
an electrolyte through a continuous flow path formed in a channel
extending between an inlet and an outlet. The channel may be formed
in an electrode plate, with a membrane on the electrode plate. If
the membrane is used, then a membrane plate may be attached to the
electrode plate, with the membrane in between the electrode plate
and the membrane plate.
[0036] Thus, novel electroplating apparatus and methods have been
shown and described. Various changes and substitutions may of
course be made without departing from the spirit and scope of the
invention. The invention, therefore, should not be limited except
by the following claims and their equivalents.
* * * * *