U.S. patent application number 10/152470 was filed with the patent office on 2003-11-27 for conditioning disk actuating system.
This patent application is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Chang, Chih-Ming.
Application Number | 20030220049 10/152470 |
Document ID | / |
Family ID | 29548490 |
Filed Date | 2003-11-27 |
United States Patent
Application |
20030220049 |
Kind Code |
A1 |
Chang, Chih-Ming |
November 27, 2003 |
Conditioning disk actuating system
Abstract
A conditioning disk actuating system for raising and lowering a
conditioning disk inside a conditioning head for the conditioning
of semiconductor wafer polishing pads. The system includes a
fluid-actuated cylinder which is coupled to a travel hub vertically
slidably mounted in a travel housing provided inside the
conditioning head. The conditioning disk is mounted on the bottom
end of a disk shaft carried by the travel hub. The fluid-actuated
cylinder is operated to selectively lower and raise the travel hub
and conditioning disk to press the disk against the polishing pad
and remove the disk from the polishing pad, respectively. A
position sensing mechanism may be provided in the conditioning head
for revealing the "up" or "down" position of the conditioning
disk.
Inventors: |
Chang, Chih-Ming; (Hsin Chu,
TW) |
Correspondence
Address: |
TUNG & ASSOCIATES
Suite 120
838 W. Long Lake Road
Bloomfield Hills
MI
48302
US
|
Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd.
|
Family ID: |
29548490 |
Appl. No.: |
10/152470 |
Filed: |
May 21, 2002 |
Current U.S.
Class: |
451/5 |
Current CPC
Class: |
B24B 53/017
20130101 |
Class at
Publication: |
451/5 |
International
Class: |
B24B 049/00; B24B
051/00 |
Claims
What is claimed is:
1. A system comprising: a conditioning head; a travel hub
vertically movably mounted in said conditioning head; a disk shaft
carried by said travel hub; a conditioning disk carried by said
disk shaft; a fluid-actuated cylinder operably engaging said travel
hub for selectively moving said travel hub between upper and lower
positions in said conditioning head; and a fluid source connected
to said fluid-actuated cylinder for flowing a fluid to and from
said fluid-actuated cylinder.
2. The system of claim 1 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
3. The system of claim 1 wherein said fluid-actuated cylinder
comprises a pneumatic cylinder.
4. The system of claim 3 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
5. The system of claim 1 further comprising a travel housing
provided in said conditioning head and wherein said travel hub is
vertically movably mounted in said travel housing.
6. The system of claim 5 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
7. The system of claim 5 wherein said fluid-actuated cylinder
comprises a pneumatic cylinder.
8. The system of claim 7 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
9. The system of claim 2 wherein said position sensing mechanism
comprises a magnetic ring carried by said travel hub, a position
sensor provided in said conditioning head in adjacent contact with
said magnetic ring, and a positioning monitor operably connected to
said position sensor.
10. The system of claim 9 wherein said fluid-actuated cylinder
comprises a pneumatic cylinder.
11. The system of claim 9 further comprising a travel housing
provided in said conditioning head and wherein said travel hub is
vertically movably mounted in said travel housing and said position
sensor is provided on said travel housing.
12. The system of claim 3 further comprising a needle valve
interposed between said fluid source and said fluid actuated
cylinder for controlling a speed of movement of said fluid actuated
cylinder from said lower position to said upper position.
13. A system comprising: a conditioning head; a travel hub
vertically movably mounted in said conditioning head; a disk shaft
carried by said travel hub; a conditioning disk carried by said
disk shaft; a link carried by said travel hub; a fluid-actuated
cylinder engaging said link for selectively moving said travel hub
between upper and lower positions in said conditioning head; and a
fluid source connected to said fluid-actuated cylinder for flowing
a fluid to and from said fluid-actuated cylinder.
14. The system of claim 12 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
15. The system of claim 12 further comprising a travel housing
provided in said conditioning head and wherein said travel hub is
vertically movably mounted in said travel housing.
16. The system of claim 14 wherein said position sensing mechanism
comprises a magnetic ring carried by said travel hub, a position
sensor provided in said conditioning head in adjacent contact with
said magnetic ring, and a positioning monitor operably connected to
said position sensor.
17. A system comprising: a conditioning head; a travel hub
vertically movably mounted in said conditioning head; a disk shaft
carried by said travel hub; a conditioning disk carried by said
disk shaft; a link having a vertical segment carried by said travel
hub and a horizontal segment extending from said vertical segment;
a fluid-actuated cylinder engaging said horizontal segment of said
link for selectively moving said travel hub between upper and lower
positions in said conditioning head; and a fluid source connected
to said fluid-actuated cylinder for flowing a fluid to and from
said fluid-actuated cylinder.
18. The system of claim 17 wherein said fluid-actuated cylinder
comprises a pneumatic cylinder.
19. The system of claim 17 further comprising a position sensing
mechanism operably engaging said travel hub for sensing a position
of said travel hub in said conditioning head.
20. The system of claim 19 wherein said position sensing mechanism
comprises a magnetic ring carried by said travel hub, a position
sensor provided in said conditioning head in adjacent contact with
said magnetic ring, and a positioning monitor operably connected to
said position sensor.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to disks used in the
conditioning of polishing pads on chemical mechanical polishers for
semiconductor wafers. More particularly, the present invention
relates to a new and improved actuating system for raising and
lowering a polishing pad conditioning disk in a pad conditioning
head of a chemical mechanical polisher.
BACKGROUND OF THE INVENTION
[0002] Apparatus for polishing thin, flat semiconductor wafers are
well-known in the art. Such apparatus normally includes a polishing
head which carries a membrane for engaging and forcing a
semiconductor wafer against a wetted polishing surface, such as a
polishing pad. Either the pad or the polishing head is rotated and
oscillates the wafer over the polishing surface. The polishing head
is forced downwardly onto the polishing surface by a pressurized
air system or similar arrangement. The downward force pressing the
polishing head against the polishing surface can be adjusted as
desired. The polishing head is typically mounted on an elongated
pivoting carrier arm, which can move the pressure head between
several operative positions. In one operative position, the carrier
arm positions a wafer mounted on the pressure head in contact with
the polishing pad. In order to remove the wafer from contact with
the polishing surface, the carrier arm is first pivoted upwardly to
lift the pressure head and wafer from the polishing surface. The
carrier arm is then pivoted laterally to move the pressure head and
wafer carried by the pressure head to an auxiliary wafer processing
station. The auxiliary processing station may include, for example,
a station for cleaning the wafer and/or polishing head, a wafer
unload station, or a wafer load station.
[0003] More recently, chemical-mechanical polishing (CMP) apparatus
has been employed in combination with a pneumatically actuated
polishing head. CMP apparatus is used primarily for polishing the
front face or device side of a semiconductor wafer during the
fabrication of semiconductor devices on the wafer. A wafer is
"planarized" or smoothed one or more times during a fabrication
process in order for the top surface of the wafer to be as flat as
possible. A wafer is polished by being placed on a carrier and
pressed face down onto a polishing pad covered with a slurry of
colloidal silica or alumina in deionized water.
[0004] A schematic of a typical CMP apparatus is shown in FIGS. 1A
and 1B. The apparatus 20 for chemical mechanical polishing consists
of a rotating wafer holder 14 that holds the wafer 10, the
appropriate slurry 24, and a polishing pad 12 which is normally
mounted to a rotating table 26 by adhesive means. The polishing pad
12 is applied to the wafer surface 22 at a specific pressure. The
chemical mechanical polishing method can be used to provide a
planar surface on dielectric layers, on deep and shallow trenches
that are filled with polysilicon or oxide, and on various metal
films.
[0005] CMP polishing results from a combination of chemical and
mechanical effects. A possible mechanism for the CMP process
involves the formation of a chemically altered layer at the surface
of the material being polished. The layer is mechanically removed
from the underlying bulk material. An altered layer is then regrown
on the surface while the process is repeated again. For instance,
in metal polishing, a metal oxide may be formed and removed
separately.
[0006] A polishing pad is typically constructed in two layers
overlying a platen with the resilient layer as the outer layer of
the pad. The layers are typically made of polyurethane and may
include a filler for controlling the dimensional stability of the
layers. The polishing pad is usually several times the diameter of
a wafer and the wafer is kept off-center on the pad to prevent
polishing a non-planar surface onto the wafer. The wafer is also
rotated to prevent polishing a taper into the wafer. Although the
axis of rotation of the wafer and the axis of rotation of the pad
are not collinear, the axes must be parallel.
[0007] In a CMP head, large variations in the removal rate, or
polishing rate, across the whole wafer area are frequently
observed. A thickness variation across the wafer is therefore
produced as a major cause for wafer non-uniformity. In the improved
CMP head design, even though a pneumatic system for forcing the
wafer surface onto a polishing pad is used, the system cannot
selectively apply different pressures at different locations on the
surface of the wafer. This effect is shown in FIG. 1C, i.e. in a
profilometer trace obtained on an 8-inch wafer. The thickness
difference between the highest point and the lowest point on the
wafer is almost 2,000 angstroms, resulting in a standard deviation
of 472 angstroms, or 6.26%. The curve shown in FIG. 1C is plotted
with the removal rates in the vertical axis and the distance from
the center of the wafer in the horizontal axis. It is seen that the
removal rates obtained at the edge portions of the wafer are
substantially higher than the removal rates at or near the center
of the wafer. The thickness uniformity on the resulting wafer after
the CMP process is poor.
[0008] The polishing pad 12 is a consumable item used in a
semiconductor wafer fabrication process. Under normal wafer
fabrication conditions, the polishing pad is replaced after about
12 hours of usage. Polishing pads may be hard, incompressible pads
or soft pads. For oxide polishing, hard and stiffer pads are
generally used to achieve planarity. Softer pads are generally used
in other polishing processes to achieve improved uniformity and
smooth surfaces. The hard pads and the soft pads may also be
combined in an arrangement of stacked pads for customized
applications.
[0009] A problem frequently encountered in the use of polishing
pads in oxide planarization is the rapid deterioration in oxide
polishing rates with successive wafers. The cause for the
deterioration is known as "pad glazing", wherein the surface of a
polishing pad becomes smooth such that slurry is no longer held in
between the fibers of the pad. This physical phenomenon on the pad
surface is not caused by any chemical reactions between the pad and
the slurry.
[0010] To remedy the pad glazing effect, numerous techniques of pad
conditioning or scrubbing have been proposed to regenerate and
restore the pad surface and thereby restore the polishing rates of
the pad. The pad conditioning techniques include the use of silicon
carbide particles, diamond emery paper, blade or knife for scraping
or scoring the polishing pad surface. The goal of the conditioning
process is to remove polishing debris from the pad surface and
re-open pores in the pad by forming micro-scratches in the surface
of the pad for improved pad lifetime. The pad conditioning process
can be carried out either during a polishing process, i.e. known as
concurrent conditioning, or after a polishing process.
[0011] Referring next to FIG. 2, a conventional CMP apparatus 50
includes a conditioning head 52 fitted with a conditioning disk 68,
which is formed by embedding or encapsulating diamond particles in
nickel coated on the surface of the conditioning disk 68; a
polishing pad 56; and a slurry delivery arm 54 positioned over the
polishing pad 56. The conditioning head 52 is mounted on a
conditioning arm 58 which is extended over the top of the polishing
pad 56 for making a sweeping motion across the entire surface of
the polishing pad 56. The slurry delivery arm 54 is equipped with
slurry dispensing nozzles 62 which are used for dispensing a slurry
solution on the top surface 60 of the polishing pad 56. Surface
grooves 64 are further provided in the top surface 60 to facilitate
even distribution of the slurry solution and to help entrapping
undesirable particles that are generated by coagulated slurry
solution or any other foreign particles which have fallen on top of
the polishing pad 56 during a polishing process. The surface
grooves 64, while serving an important function of distributing the
slurry, also presents a processing problem when the pad surface 60
gradually wears out after prolonged use.
[0012] As illustrated in FIGS. 3 and 4, the conventional
conditioning head 52 typically includes an air cavity 72 in which
is slidably disposed a typically rubber diaphragm 70. The
conditioning disk 68 is attached to a disk shaft 80 extending
through the diaphragm 70. An air intake tube 74 and an air vacuum
tube 76 are provided in fluid communication with the air cavity 72,
and each is connected to an air/vacuum source 78 such as an SCM
Venturi air/vacuum pump. Accordingly, to facilitate conditioning
the polishing pad 56, pressurized air is introduced from the
air/vacuum source 78 through the air intake tube 74 and into the
air cavity 72, where the air presses downwardly against the
diaphragm 70, which in turn presses the conditioning disk 68
against the polishing pad 56 to score and condition the polishing
pad 56 as the disk shaft 80 rotates the conditioning disk 68. The
conditioning operation is terminated by withdrawing air from the
air cavity 72 through the air vacuum tube 76, wherein the resulting
reduced air pressure in the air cavity 72 raises the diaphragm 70
and withdraws the conditioning disk 68 from contact with the
polishing pad 56.
[0013] One of the problems encountered in operation of the
conventional conditioning head 52 is frequent rupturing or
reduction in elasticity of the diaphragm 70 after prolonged use.
Consequently, pressurized air in the air cavity 72 tends to escape
the conditioning head 52 through the diaphragm 70 upon an attempt
to press the conditioning disk 68 against the polishing pad 56 for
conditioning of the polishing pad 56. Further, the vacuum pressure
in the air cavity 72 is dispelled by leakage of air into the
conditioning head 52 through the ruptured diaphragm 70 upon an
attempt to withdraw the conditioning disk 68 from the polishing pad
56. The reduction in air pressure in the air cavity 72 results in
inadequate downward force of the conditioning disk 68 against the
polishing pad 56 to effectively condition the polishing pad 56. As
a result, the diaphragm 70 and other components of the conditioning
head 52 or vacuum system must be frequently replaced, and the
replacement operation may require 3-4 hours to complete, resulting
in substantial down time. Further, since the conditioning head 52
lacks any sensing mechanism to reveal the position of the
conditioning disk 68 therein, personnel operating the conditioning
head 52 are incapable of readily determining whether the
conditioning disk 68 is in the "up" position of FIG. 3 or the
"down" position of FIG. 4.
[0014] Accordingly, a more durable system is needed for raising and
lowering a conditioning disk in a conditioning head of a chemical
mechanical polisher to prevent the need for frequent replacement of
parts.
[0015] An object of the present invention is to provide a new and
improved conditioning disk actuating system for lowering and
raising a conditioning disk in a conditioning head.
[0016] Another object of the present invention is to provide a
conditioning disk actuating system for lowering and raising a
conditioning disk in a conditioning head, which system includes
durable parts to provent the need for frequent replacement of
parts.
[0017] Still another object of the present invention is to provide
a system for reliably lowering and raising a conditioning disk in a
conditioning head over a period of prolonged operation.
[0018] Yet another object of the present invention is to provide a
system which is capable of sensing the "up" or "down" position of a
conditioning disk inside a conditioning head for conditioning wafer
polishing pads.
[0019] Another object of the present invention is to provide a
conditioning disk actuating system which is capable of sustaining a
stable downward force against a conditioning disk during
conditioning of a polishing pad using the conditioning disk.
SUMMARY OF THE INVENTION
[0020] In accordance with these and other objects and advantages,
the present invention comprises a new and improved conditioning
disk actuating system for raising and lowering a conditioning disk
inside a conditioning head for the conditioning of semiconductor
wafer polishing pads. The system includes a fluid-actuated cylinder
which is coupled to a travel hub vertically slidably mounted in a
travel housing provided inside the conditioning head. The
conditioning disk is mounted on the bottom end of a disk shaft
carried by the travel hub. The fluid-actuated cylinder is operated
to selectively lower and raise the travel hub and conditioning disk
to press the disk against the polishing pad and remove the disk
from the polishing pad, respectively. A position sensing mechanism
may be provided in the conditioning head for revealing the "up" or
"down" position of the conditioning disk.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The invention will now be described, by way of example, with
reference to the accompanying drawings, in which:
[0022] FIG. 1A is a cross-sectional view of a conventional chemical
mechanical polishing apparatus;
[0023] FIG. 1B is an enlarged, cross-sectional view of a section of
a wafer and polishing pad with a slurry solution therein between,
in a conventional disk polishing operation;
[0024] FIG. 1C is a graph illustrating the changes in removal rates
as a function of distance on a wafer after a polishing pad is
repeatedly used;
[0025] FIG. 2 is a perspective view of a conventional CMP polishing
pad with a slurry dispensing arm and a conditioning disk positioned
on top;
[0026] FIG. 3 is a schematic view illustrating interior components
of a conventional conditioning head, with the diaphragm and
conditioning disk components of the conditioning head shown in the
"up" position;
[0027] FIG. 4 is a schematic view illustrating interior components
of a conventional conditioning head, with the diaphragm and
conditioning disk components of the conditioning head shown in the
"down" position;
[0028] FIG. 5A is a schematic view illustrating a conditioning disk
actuating system of the present invention, with the conditioning
disk component of the conditioning head thereof shown in the "up"
position;
[0029] FIG. 5B is a schematic view illustrating a conditioning disk
actuating system of the present invention, with the conditioning
disk component of the conditioning head thereof shown in the "down"
position;
[0030] FIG. 6 is a cross-sectional view of a disk shaft component
typically used in attaching a conditioning disk to the conditioning
head of the present invention, more particularly illustrating an
illustrative, threaded technique for mounting the conditioning
disk;
[0031] FIG. 7 is an enlarged sectional view of the travel hub
component of the present invention, more particularly illustrating
an illustrative sensor mechanism for sensing the "up" and "down"
positions of the conditioning disk in the conditioning head;
and
[0032] FIG. 8 is a schematic illustrating an illustrative control
system for the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] The present invention is directed to a conditioning disk
actuating system for selectively lowering and pressing a
conditioning disk of a conditioning head against a polishing pad
for conditioning of the polishing pad and raising the conditioning
disk from contact with the polishing pad after the conditioning
operation. The system of the present invention is generally
indicated by reference numeral 28 and includes a conditioning head
29 mounted on the end of an elongated conditioning arm 85. The
conditioning head 29 includes a head interior 30 through which a
disk shaft 33 extends. The upper end of the disk shaft 33 may be
conventionally fitted with a belt gear (not illustrated) which
engages a belt and motor (not illustrated) for rotation of the disk
shaft 33 inside the head interior 30. A travel housing 31 is
mounted in the bottom of the interior 30 and includes an
inwardly-extending housing flange 39. A flange interior 43 is
defined by the housing flange 39. A travel hub 32 is mounted on the
disk shaft 33 and is stationary with respect to the disk shaft 33
as the disk shaft 33 rotates therein. Accordingly, ball bearings
(not illustrated) or other mechanism may be provided at the
interface of the travel hub 32 and the disk shaft 33 to facilitate
smooth rotation of the disk shaft 33 in the travel hub 32. The
travel hub 32 is mounted for vertical movement with the disk shaft
33 inside the flange interior 43. A bottom plate 35 is mounted on
the bottom surface of the travel housing 31 and is fitted with a
central plate opening 49 (FIG. 5B). When the travel hub 32 and disk
shaft 33 are disposed in the uppermost position inside the flange
interior 43, the plate opening 49 accommodates a conditioning disk
36 which is typically removably mounted on the bottom end of the
disk shaft 33, as illustrated in FIG. 5A. When the travel hub 32
and disk shaft 33 are disposed in the lowermost position inside the
flange interior 43, the conditioning disk 36 is displaced
downwardly from the plate opening 49, as illustrated in FIG. 5B. As
illustrated in FIG. 6, the conditioning disk 36 is typically
removably attached to the bottom end of the disk shaft 33 by
threading nipple threads 38 on an attachment nipple 37 extending
upwardly from the conditioning disk 36 with companion shaft threads
34 inside the disk shaft 33.
[0034] A magnetic position sensor 88, which may be conventional,
may be mounted against the travel housing 31 in the flange interior
43. A magnetic ring 90 circumscribes the travel hub 32 in adjacent
contact with the position sensor 88. As illustrated in FIG. 7, the
position sensor 88 is connected to an alarm or other positioning
monitor 92, which may be conventional, typically by means of wiring
93. Accordingly, magnetic attraction between the position sensor 88
and the magnetic ring 90 along the various locations on the
position sensor 88 is interpreted by the positioning monitor 92
with regard to the vertical location of the travel hub 32 and thus,
the disk shaft 33 in the flange housing 43. This, in turn, readily
indicates to operating personnel whether the conditioning disk 36
is in the upper position of FIG. 5A or the lower, operational
position of FIG. 5B. It is understood that any suitable alternative
vertical positioning monitor known by those skilled in the art may
be used to monitor the position of the travel hub 32 inside the
flange interior 43 and thus, the "up" or "down" position of the
conditioning disk 36.
[0035] As illustrated in FIGS. 5A and 5B, the system 28 of the
present invention further includes a fluid-actuated cylinder 44
typically mounted on the bottom portion 86 of the conditioning arm
85. A piston 48 slidably disposed in the housing 45 of the
fluid-actuated cylinder 44 is attached to the lower end of a piston
shaft 82. A top fluid hose 46 and a bottom fluid hose 47 extend
from the housing 45 and are connected to a fluid source 95, which
may be a source of compressed clean, dry air (CDA), or
alternatively, a pump and supply mechanism for hydraulic fluid. The
piston shaft 82 extends upwardly from the piston 48 inside the
housing 45 and through an opening (not illustrated) in the bottom
portion 86 of the conditioning arm 85. A link coupling 83 is
provided on the upper end of the piston shaft 82 inside the
conditioning arm 85.
[0036] As further illustrated in FIGS. 5A and 5B, a link 40
connects the link coupling 83 to the travel hub 32. The link 40
typically includes a horizontal segment 41 which extends
horizontally from the link coupling 83 and a vertical segment 42
which extends downwardly from the extending end of the horizontal
segment 41, through a link opening (not illustrated) provided in
the housing flange 39 of the travel hub 32, and is attached to the
travel hub 32 typically by means of a standard base bearing.
Accordingly, by operation of the fluid source 95 to introduce fluid
under pressure into the fluid-actuated cylinder 44 through the top
fluid hose 46, the fluid pushes downwardly against the top surface
of the piston 48, sliding the piston 48 downwardly in the housing
45. Consequently, the piston shaft 82 lowers the link coupling 83,
which lowers the link 40 through the link opening in the housing
flange 39. This action lowers the travel hub 32 and disk shaft 33
inside the flange interior 43, and the disk shaft 33 in turn lowers
the conditioning disk 36 from the plate opening 49 and against the
upper surface of a polishing pad 97 for conditioning thereof, as
illustrated in FIG. 5B and hereinafter further described.
Conversely, by operation of the fluid source 95 to introduce fluid
under pressure into the fluid-actuated cylinder 44 through the
bottom fluid hose 47, the fluid pushes upwardly against the bottom
surface of the piston 48, thereby sliding the piston 48 upwardly in
the housing 45. Consequently, the piston shaft 82 raises the link
coupling 83, which raises the link 40 through the link opening in
the housing flange 39. This action raises the travel hub 32 and
disk shaft 33 inside the flange interior 43, and the disk shaft 33
in turn raises the conditioning disk 36 from the upper surface of
the polishing pad 97 and again positions the conditioning disk 36
in the plate opening 49 of the bottom plate 35, as illustrated in
FIG. 5A.
[0037] Referring again to FIGS. 5A and 5B, the system 28 of the
present invention is operated to condition a polishing pad 97
supported on a platen 98 of a chemical mechanical polisher (not
shown). The conditioning head 29 of the present invention is
initially positioned over the surface of the polishing pad 97, and
as the platen 98 rotates the polishing pad 97 thereon, a polishing
slurry (not illustrated) is deposited on the surface of the
rotating polishing pad 97. Simultaneously, as the disk shaft 33 and
attached conditioning disk 36 are rotated in the conditioning head
29, the fluid-actuated cylinder 44 is operated via the fluid source
95 to lower the travel hub 32 and disk shaft 33 in the conditioning
head 29 from the position illustrated in FIG. 5A to the position
illustrated in FIG. 5B, in the manner heretofore described.
Accordingly, as the conditioning head 29 is moved horizontally
across the surface of the polishing pad 97 by pivoting action of
the conditioning arm 85, in conventional fashion, the rotating
conditioning disk 36 scores and shears the surface of the polishing
pad 97 to condition the polishing pad 97 in conventional fashion.
It will be appreciated by those skilled in the art that the fluid
source 95 and fluid-actuated cylinder 44 are capable of applying
the conditioning disk 36 against the polishing pad 97 at a steady
pressure throughout the conditioning operation.
[0038] To terminate the conditioning operation, the rotating
conditioning disk 36 is removed from contact with the polishing pad
97 by operating the fluid-actuated cylinder 44 to raise the piston
48 in the housing 45 and thus, raise the travel hub 32 and disk
shaft 33 in the conditioning head 29 and remove the conditioning
disk 36 from contact with the polishing pad 97. It will be
appreciated by those skilled in the art that the positioning
monitor 92, in conjunction with the position sensor 88 on the
stationary travel housing 31 and the magnetic ring 90 on the travel
hub 32, provide a reliable indicator to operating personnel of the
relative position of the conditioning disk 36 with respect to the
polishing pad 97 throughout the conditioning operation.
[0039] Referring next to FIG. 8, a schematic is shown illustrating
a typical pneumatic control valve system in triplicate for each of
three conditioning disk actuating systems of the present invention,
located at three respective chemical mechanical polishers (not
illustrated) in a semiconductor fabrication facility. In the
embodiment of the present invention wherein the fluid source 95 is
a source of clean, dry air (CDA), the CDA source 95 is
pneumatically connected to each of three "up" control valves 4
typically through each of three needle valves 2 that can be used to
control the upward speed of each travel hub in the corresponding
travel housing. Each "up" control valve 4 facilitates flow of CDA
into the fluid-actuated cylinder 44 through the bottom fluid hose
47 (FIGS. 5A and 5B) thereof to facilitate raising the travel hub
32 and disk shaft 33 in each conditioning head 29. A "down" control
valve 6 facilitates flow of CDA into the fluid-actuated cylinder 44
through the top fluid hose 46 thereof to facilitate lowering the
travel hub 32 and disk shaft 33 in each conditioning head 29 and
pressing the conditioning disk 36 against the polishing pad 97.
Typically, the "down" control valves 6 are components of the
conventional diaphragm-actuated control system (such as the SCM
Venturi air/vacuum system) having the conditioning head 52
heretofore described with respect to FIGS. 2-4. Accordingly, the
fluid-actuated cylinders 44 and the "up" control valves 4 of the
present invention may be retrofitted to the "down" control valves 6
as part of the conventional diaphragm-actuated control system. It
is understood that the schematic of FIG. 8 represents only one
example of a pneumatic valve control system which is suitable for
controlling the conditioning disk actuating system of the present
invention.
[0040] While the preferred embodiments of the invention have been
described above, it will be recognized and understood that various
modifications can be made in the invention and the appended claims
are intended to cover all such modifications which may fall within
the spirit and scope of the invention.
[0041] Having described my invention with the particularity set
forth above, I claim:
* * * * *