U.S. patent application number 10/964310 was filed with the patent office on 2005-05-05 for method and apparatus for two-part cmp retaining ring.
Invention is credited to Hengel, Raymond J. JR..
Application Number | 20050095964 10/964310 |
Document ID | / |
Family ID | 34555812 |
Filed Date | 2005-05-05 |
United States Patent
Application |
20050095964 |
Kind Code |
A1 |
Hengel, Raymond J. JR. |
May 5, 2005 |
Method and apparatus for two-part CMP retaining ring
Abstract
A two piece retaining ring used for chemical mechanical
polishing of semiconductor substrates comprising a relatively rigid
upper portion and a less rigid lower portion. The two pieces of the
ring are secured to each other by snapping a central channel and
extending arms over a central neck extension of the upper part.
Inventors: |
Hengel, Raymond J. JR.;
(Round Rock, TX) |
Correspondence
Address: |
SPM, INC.
300 Park Central Boulevard
Georgetown
TX
78626
US
|
Family ID: |
34555812 |
Appl. No.: |
10/964310 |
Filed: |
October 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60509994 |
Oct 9, 2003 |
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Current U.S.
Class: |
451/285 ;
451/390 |
Current CPC
Class: |
B24B 37/32 20130101 |
Class at
Publication: |
451/285 ;
451/390 |
International
Class: |
B24B 005/00 |
Claims
What is claimed is:
1. A retaining ring for a carrier head, the retaining ring
comprising: a first rigid annular portion comprising a downwardly
extending annular central neck portion; a second annular portion of
a less rigid material than the first portion, the second portion
comprising a central upwardly facing channel; and a snap connection
means such that the central upwardly facing channel of the second
annular portion may be snapped over the downwardly extending
annular central neck portion of the first rigid annular
portion.
2. The retaining ring of claim 1 further comprising a rotation
prevention means which prevents the second annular portion from
rotating with respect to the first rigid annular portion.
3. The retaining ring of claim 1 further comprising a vibration
reduction means between the second annular portion and the first
rigid annular portion.
4. The retaining ring of claim 1 wherein the snap connection means
is at least one lip on the second annular portion which fits into
an annular slot on the first rigid annular portion.
5. A retaining ring for a carrier head, the retaining ring
comprising: a first rigid annular portion comprising a downwardly
extending annular central neck portion having a first wall surface
toward the center of the retaining ring and a second wall surface
away from the center of the retaining ring, a first annular inset
in the upper portion of the first wall surface, and a second
annular inset in the upper portion of the second wall surface; and
a second annular portion of a less rigid material than the first
portion, the second portion comprising a central upwardly facing
channel having a third wall toward the center of the retaining ring
and a fourth wall away from the center of the retaining ring, a
first lip in the upper portion of the third wall, and a second lip
in the upper portion of the fourth wall, such that the downwardly
extending annular central neck portion of the first rigid annular
portion nests in the central upwardly facing channel of the second
annular portion, and the first lip engages the first annular inset,
and such that the second lip engages the second annular inset.
6. A retaining ring for a carrier head, the retaining ring
comprising: a first rigid annular portion comprising an upper
mounting surface, such that the upper mounting surface may be
removable affixed to the carrier head, a lower mating surface, an
inside surface toward the center of the retaining ring between the
lower mating surface and the upper mounting surface, an annular
inset in the upper portion of the inside surface, an outside
surface away from the center of the retaining ring between the
lower mating surface and the upper mounting surface, and an annular
inset in the upper portion of the outside surface; a second annular
portion of a less rigid material than the first portion, the second
portion comprising a lower wear surface, an upper mating surface,
such that the upper mating surface engages the lower mating surface
of the first rigid annular portion, an inside wall extending
upwardly from the upper mating surface, the inside wall comprising
an outside surface away from the center of the retaining ring, and
a lip in the upper portion of the outside surface, such that the
lip engages the annular inset in the upper portion of the inside
surface of the first rigid annular portion, and an outside wall
extending upwardly from the upper mating surface, the outside wall
comprising an inside surface toward the center of the retaining
ring, and a lip in the upper portion of the inside surface, such
that the lip engages the annular inset in the upper portion of the
outside surface of the first rigid annular portion.
7. The retaining ring of claim 6 further comprising a beveled edge
between the lower mating surface and the lower portion of the
outside surface of the first rigid annular portion; and a beveled
edge between the upper mating surface and the lower portion of the
inside surface of the outside wall of the second annular
portion.
8. The retaining ring of claim 7 further comprising a beveled edge
between the lower mating surface and the lower portion of the
inside surface of the first rigid annular portion; and a beveled
edge between the upper mating surface and the lower portion of the
outside surface of the inside wall of the second annular
portion.
9. A method of assembling the second annular portion onto the first
rigid annular portion, the method comprising providing a fixture
comprising a top plate having a plurality of alignment holes, and a
bottom plate having a plurality of dowel pins inserted into
alignment holes, such that a spring is inserted over each dowel
pin, the bottom plate including a recess for accepting the second
annular portion of the retaining ring; placing the second annular
portion in the recess of the bottom plate; positioning the first
rigid annular portion over the second annular portion; placing the
top plate over the dowel pins; and applying a downward force to the
top plate, thereby driving the neck of the first rigid annular
portion into the channel of the second annular portion.
10. A method of removing the second annular portion from the first
rigid annular portion, the method comprising inserting a plurality
of screws into the mounting holes on the first rigid annular
portion; alternately tightening the screws thereby forcing the
second annular portion away from the first rigid annular portion.
Description
FIELD OF INVENTION
[0001] This invention relates to a two part retaining ring
typically used in chemical mechanical polishing operations.
BACKGROUND
[0002] The present invention relates to a retaining ring used in
the process of chemical mechanical polishing of semiconductor
substrates. The substrate is typically a thin disc of semiconductor
material with deposited alternate layers of conductive,
semiconductive, and insulating materials. The layers are etched to
produce electrical circuitry on the surface of the substrate. A
typical substrate has a series of layers deposited and circuitry
etched. The deposition and etching process after many layers
produces a non flat top surface. This unflatness prevents accurate
deposition of subsequent layers. Planarization of the substrate is
periodically required to maintain an acceptable substrate surface.
Chemical mechanical polishing of the topmost surface of the
substrate produces a sufficiently flat surface to allow accurate
subsequent deposition and etching of layers. This method of
planarization is affected on a substrate by use of a polishing
machine. Among the many subassemblies of this machine is the
polishing head or carrier head. The polishing head contains among
its components a retaining ring. This ring positions and retains
the substrate allowing the other components of the head to exert
pressure against the substrate which in turn moves relative to a
polishing pad, usually wetted by a polishing medium or slurry.
[0003] The retaining ring is typically composed of two pieces. The
first, or upper, piece is usually of a metal material such as
stainless steel, aluminum, or molybdenum, but may be other
materials. The second, or lower, piece is of a plastic material
such as polyphenylene sulfide (PPS), polyethylene terephthalate,
polyetheretherketone, polybutylene terephthalate or Ertalyte TX
from Quadrant Engineering Plastic Products.
[0004] U.S. Pat. No. 6,251,215 to Zuniga describes a two part
chemical mechanical polishing (CMP) retaining ring where the first
part is polyphenylene sulfide (PPS) and the second part is metal
and the parts are joined by an epoxy adhesive. The '215 patent
references, but does not describe, mating the first piece to the
second piece by a plurality of individual screws.
[0005] U.S. Pat. No. 6,186,880 to Gonzalez et al describes a
recyclable retaining ring assembly comprising a plastic wear ring
portion with a raised neck 38 which is inserted into an opposing
channel or groove 36 of a metal backing ring 34.
[0006] U.S. Pat. No. 6,089,960 to Messer describes the use of one
or more elastomeric shim rings in the CMP head.
[0007] The plastic portion of the ring is in physical contact with
a polishing pad and slurry. Over a certain period of time the
exposed surface of the ring is worn down due to the abrasiveness of
the pad and slurry. Eventually the ring is no longer functional and
must be replaced.
[0008] It is desirable to provide a method of replacing the plastic
wear portion of the two part ring. In some embodiments, the
replacement of the plastic wear portion may be conducted at a
customer site so that shipping cost can be reduced. Alternately,
the entire ring may be shipped back to a supplier for rework, where
the plastic wear portion would be replaced.
SUMMARY
[0009] The invention is directed toward a method of fastening
together two parts of a retaining ring used in the chemical
mechanical polishing process of a semiconductor substrate. The
first, or upper, part is typically a metal material such as
stainless steel, aluminum, or molybdenum. The second, or lower,
part is of a plastic material such as PPS.
[0010] One embodiment of the present invention is a plastic ring
which has inner and outer peripheral snap features to snap onto the
metal backup ring. In one embodiment, the snap features include a
lip projection which engages a peripheral slot in a neck extension
in a metal backup ring.
[0011] The present invention permits less expensive replacement
rings, and faster maintenance relative to prior art retaining
rings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other objects and advantages of the present
invention are set forth below and further made clear by reference
to the drawings, wherein:
[0013] FIG. 1A is a top view of a retaining ring.
[0014] FIG. 1B is a side view of the retaining ring of FIG 1A.
[0015] FIG. 2 is an exploded top perspective view of a retaining
ring.
[0016] FIG. 3 is a cross section view A-A of the ring of FIG. 1
[0017] FIG. 4 is a cross section view B-B of the ring of FIG. 1
[0018] FIG. 5 is a detailed cross section view of the upper part of
the ring of FIG. 1
[0019] FIG. 6 is a detailed cross section view of the upper part of
the ring of FIG. 1
[0020] FIG. 7 is an exploded perspective view of an assembly
fixture for snapping the lower part of the ring onto the upper part
of the ring.
DETAILED DESCRIPTION OF EMBODIMENT--Lower Part Snapping onto Upper
Part
[0021] Referring to FIG. 1A which is a top view of a retaining ring
100, the ring includes an upper part 150 and a lower part 200 (not
shown). Both the upper part and the lower part are annular rings.
The retaining ring 150 is typically mounted to a carrier head (not
shown) by screws 110 along the top surface of the upper part.
[0022] FIG. 1B is a side view of the retaining ring of FIG. 1A,
which shows the lower part of the ring 200 covering the outside
edge of the upper part 150 (shown by hidden line). The lower part
may include a gap which facilitates expanding the plastic portion
slightly to fit over the upper portion. In this embodiment, the
lower part is snapped onto the upper part.
[0023] Referring now to FIG. 2 which is an exploded top perspective
view of a retaining ring, the two piece retaining ring 100 is
composed of two parts, the first or upper part 150 is typically
made of a metal, and the second or lower part 200 is typically made
of plastic such as, polyphenylene sulfide (PPS), polyethylene
terephthalate, polyetheretherketone, polybutylene terephthalate or
Ertalyte TX. The lower part includes a central annular channel 250
which receives an extended neck portion (not shown) of the upper
part.
[0024] Referring now to FIGS. 3 and 4 which are cross section views
of the assembled part and to FIGS. 5 and 6 which are detailed cross
section views of the upper and lower parts respectively, the upper
part 150 includes a downwardly extending annular central neck
portion 160 which cover substantially all of the width of the upper
part. The downwardly extending annular central neck portion is
received in the central annular channel 250 of the lower part. The
downwardly extending annular central neck portion has a first wall
surface 162 toward the center of the retaining ring and a second
wall surface 172 away from the center of the retaining ring. There
is a first annular inset 164 in the upper portion of the first wall
surface 162, and a second annular inset 174 in the upper portion of
the first wall surface 172.
[0025] The central annular channel 250 includes an upper mating
surface 255, an inside wall 260 toward the center of the retaining
ring extending upwardly from the upper mating surface, and an
outside wall 270 away from the center of the retaining ring
extending upwardly from the upper mating surface. The inside wall
has a third wall surface 260 which may include a first lip 262
which engages the first annular inset 164, and the outside wall has
a fourth wall surface 270 which may include a second lip 272 which
engages the first annular inset 174.
[0026] The upper part may include at least one hole 180 for
receiving a pins 190. The hole typically extends 210 partially
through the lower part 200 so that the pin prevents a rotation of
the lower part relative to the upper part.
[0027] The neck portion 160 and the central annular channel 250 may
include radiused comers as shown by 165, 175, 264, and 274. In one
embodiment, the inside wall 162 of the neck portion 160 is
perpendicular to the top mounting surface 152 of the upper part. In
another embodiment, the inside wall 162 has a slight taper, such as
about 2 degrees toward the outside of the ring as shown in FIG. 5B.
This taper typically begins below the first inset 164.
[0028] In one embodiment, the first material is stainless steel and
the second material is polyphenylene sulfide which includes
TechTron.RTM. by DSM, Quadrant Engineering Plastic Products,
Ryton.RTM. by Chevron-Phillips, and by Ensinger Corporation. In
other embodiments, the second piece is a plastic material such as,
polyethylene terephthalate, polyetheretherketone, polybutylene
terephthalate or Ertalyte TX.
DETAILED DESCRIPTION OF EMBODIMENT--Detailed Dimensions
[0029] In one embodiment, the first wall has a thickness of about
0.108 inches and a height of about 0.250 inches; the first lip has
a height of about 0.023 inches and has an extension of about 0.005
inches; the second wall has a thickness of about 0.085 inches and a
height of about 0.690 inches; and the second lip has a height of
about 0.039 inches and has an extension of about 0.008 inches.
DETAILED DESCRIPTION OF EMBODIMENT--Vibration Isolation
[0030] In this embodiment, a vibration isolation element, such as
an o-ring or RTV sealant is employed between the lower part wear
portion of the ring and the upper part backing portion of the
ring.
DETAILED DESCRIPTION OF EMBODIMENT--Fixture
[0031] Referring now to FIG. 7 which is an exploded perspective
view of an assembly fixture for snapping the lower part onto the
upper part, the fixture 400 includes an upper plate 410 and a lower
plate 420. Dowels pins 430-433 are inserted into the lower plate
and through corresponding holes 440-443 in the upper plate. The
dowel pins include springs 450-453. The lower plate 420 includes a
recess 460 for receiving the bottom part of the retaining ring. An
O-ring 470 may be placed in a portion of the recess 460.
[0032] For assembly, the lower part is placed into the recess 460
of the lower plate 420 which has the dowel pins and springs in
place as shown in FIG. 7. The upper part is placed over the lower
part, and the upper plate is inserted over the dowel pins. The
upper plate is then forced downward, thereby pushing the neck
extension of the upper part into the central annular channel of the
lower part.
[0033] In order to remove a lower plastic part from the upper part,
long screws may be inserted through the twelve mounting holes 110
in the upper part in order to break off the used lower part.
* * * * *