U.S. patent application number 11/065702 was filed with the patent office on 2005-11-17 for contaminant reducing substrate transport and support system.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Ahman, Kurt J., Angelo, Darryl, Fay, Richard, Hagerty, Christopher, Khurana, Nitin, Leopold, Matthew, Martin, Todd W., Ng, Edward, Parkhe, Vijay D., Rice, Michael, Ronan, Timothy, Sansoni, Steve, Suh, Song-Moon, Tsai, Matthew C..
Application Number | 20050252454 11/065702 |
Document ID | / |
Family ID | 34861866 |
Filed Date | 2005-11-17 |
United States Patent
Application |
20050252454 |
Kind Code |
A1 |
Parkhe, Vijay D. ; et
al. |
November 17, 2005 |
Contaminant reducing substrate transport and support system
Abstract
A lifting assembly can lift a substrate from a substrate support
and transport the substrate. The lift assembly has a hoop sized to
fit about a periphery of the substrate support, and a pair of
arcuate fins mounted on the hoop, each arcuate fin comprising a
pair of opposing ends having ledges that extend radially inward,
each ledge having a raised protrusion to lift a substrate so that
the substrate contacts substantially only the raised protrusion,
thereby minimizing contact with the ledge, when the pair of fins is
used to lift the substrate off the substrate support. The lifting
assembly and other process chamber components can have a
diamond-like coating having interlinked networks of (i) carbon and
hydrogen, and (ii) silicon and oxygen. The diamond-like coating has
a contact surface having a coefficient of friction of less than
about 0.3, a hardness of at least about 8 GPa, and a metal
concentration level of less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal. The contact surface reduces contamination
of a substrate when directly or indirectly contacting a
substrate.
Inventors: |
Parkhe, Vijay D.; (San Jose,
CA) ; Leopold, Matthew; (Ithaca, NY) ; Ronan,
Timothy; (San Jose, CA) ; Martin, Todd W.;
(Mountain View, CA) ; Ng, Edward; (San Jose,
CA) ; Khurana, Nitin; (Milpitas, CA) ; Suh,
Song-Moon; (Sunnyvale, CA) ; Fay, Richard;
(San Jose, CA) ; Hagerty, Christopher; (Aptos,
CA) ; Rice, Michael; (Pleasanton, CA) ;
Angelo, Darryl; (Sunnyvale, CA) ; Ahman, Kurt J.;
(San Jose, CA) ; Tsai, Matthew C.; (Cupertino,
CA) ; Sansoni, Steve; (Livermore, CA) |
Correspondence
Address: |
Janah & Associates, Inc.
Suite 106
650 Delancey Street
San Francisco
CA
94107
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
34861866 |
Appl. No.: |
11/065702 |
Filed: |
February 23, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11065702 |
Feb 23, 2005 |
|
|
|
10786876 |
Feb 24, 2004 |
|
|
|
Current U.S.
Class: |
118/729 |
Current CPC
Class: |
Y10T 279/23 20150115;
H01L 21/6831 20130101; H01L 21/6875 20130101; C23C 16/463 20130101;
H01L 21/68757 20130101 |
Class at
Publication: |
118/729 |
International
Class: |
C23C 016/00 |
Claims
What is claimed is:
1. A substrate transfer arm capable of transferring a substrate
into and out of a process chamber, the transfer arm comprising: (a)
a blade; and (b) a diamond-like coating on the blade, the
diamond-like coating comprising interlinked networks of (i) carbon
and hydrogen, and (ii) silicon and oxygen, and the diamond-like
coating having a contact surface comprising: (i) a coefficient of
friction of less than about 0.3; (ii) a hardness of at least about
8 GPa; and (iii) a metal concentration level of less than about
5.times.10.sup.12 atoms/cm.sup.2 of metal, whereby the contact
surface reduces contamination of a substrate when directly or
indirectly contacting a substrate.
2. A substrate transfer arm according to claim 1 wherein the
contact arm comprises one or more raised protrusions so that the
substrate contacts substantially only the raised protrusions,
thereby minimizing contact with the blade.
3. A support structure according to claim 1 wherein the
diamond-like coating comprises a thickness of from about 0.02 to
about 20 microns.
4. A support structure according to claim 1 wherein the
diamond-like coating comprises a wear factor of less than
5.times.10.sup.6 mm.sup.3/Nm.
5. A support pedestal capable of reducing particulate contamination
of a substrate, the support pedestal comprising: (a) a pedestal
structure comprising a disc having a recessed peripheral ledge; and
(b) a diamond-like coating on the disc, the diamond-like coating
comprising interlinked networks of (i) carbon and hydrogen, and
(ii) silicon and oxygen, and the diamond-like coating having a
contact surface comprising: (i) a coefficient of friction of less
than about 0.3; (ii) a hardness of at least about 8 GPa; and (iii)
a metal concentration level of less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal, whereby the contact surface reduces
contamination of a substrate when directly or indirectly contacting
a substrate.
6. A support pedestal according to claim 5 wherein the recessed
peripheral ledge comprises a radial width that is sized
sufficiently large to avoid contact with a contaminated backside
perimeter edge.
7. A support pedestal according to claim 5 wherein the recessed
peripheral ledge comprises a radial width of at least about
{fraction (1/150)}.sup.th the diameter of the disc.
8. A support pedestal according to claim 5 wherein the recessed
peripheral ledge comprises a radial width that is at least about 2
mm wide.
9. A support pedestal according to claim 5 wherein the recessed
peripheral ledge comprises a depth of at least about 2 mm.
10. A lifting assembly to lift a substrate from a substrate support
and transport the substrate, the lifting assembly comprising: (a) a
hoop sized to fit about a periphery of the substrate support; and
(b) a pair of arcuate fins mounted on the hoop, each arcuate fin
comprising a pair of opposing ends having ledges that extend
radially inward, each ledge having a raised protrusion to lift a
substrate so that the substrate contacts substantially only the
raised protrusion, thereby minimizing contact with the ledge, when
the pair of fins is used to lift the substrate off the substrate
support.
11. A substrate lifting assembly according to claim 10 wherein the
support ledges extend inwardly from the opposing ends by at least
about 4 mm.
12. A substrate lifting assembly according to claim 10 wherein the
raised protrusions are spaced inwardly by at least about 4 mm from
the opposing ends.
13. A substrate lifting assembly according to claim 10 wherein the
raised protrusions comprise a height above a surface of the support
ledge of at least about 1 mm.
14. A substrate lifting assembly according to claim 10 further
comprising a second pair of arcuate ends mounted below the first
pair.
15. A substrate lifting assembly according to claim 10 wherein the
pair of arcuate fins comprises at least one of stainless steel and
aluminum.
16. A substrate lifting assembly according to claim 10 wherein the
pair of arcuate fins comprises at least one of alumina and
quartz.
17. A substrate lifting assembly according to claim 10 wherein the
arcuate fins comprise a diamond-like coating thereon, the
diamond-like coating comprising interlinked networks of (i) carbon
and hydrogen, and (ii) silicon and oxygen, and the diamond-like
coating having a contact surface comprising: (i) a coefficient of
friction of less than about 0.3; (ii) a hardness of at least about
8 GPa; and (iii) a metal concentration level of less than about
5.times.10.sup.12 atoms/cm.sup.2 of metal.
18. A heat exchanging support comprising: (a) a body having a
substrate receiving surface with a pattern of grooves; (b) a
diamond-like coating covering the substrate receiving surface, the
diamond-like coating comprising a network of carbon, hydrogen,
silicon and oxygen, the substrate receiving surface comprising a
pattern of grooves thereon; and (c) a heat exchanger.
19. A support according to claim 18 wherein the heat exchanger
comprising at least one of (i) a heater, and (ii) conduits for
passing a heat exchange fluid therethrough.
20. A support according to claim 18 wherein the heat exchanger
comprises a heater.
21. A support according to claim 18 wherein the heat exchanger
comprises a conduit for passing a heat exchange fluid
therethrough.
22. A support according to claim 18 wherein the pattern of grooves
is capable of equalizing the pressure on the front and backside of
the substrate placed on the substrate receiving surface.
23. A support according to claim 18 wherein the pattern of grooves
comprises a plurality of circle grooves with different radii, and a
plurality of radius grooves that extend radially across the
receiving surface and substantially only between the circle
grooves.
24. A support according to claim 23 wherein the circle grooves
comprise a first circle groove having a first radius and a second
circle groove having a second radius, the second radius being
larger than the first radius, and wherein the radius grooves extend
substantially only from the first circle groove to the second
circle groove.
25. A support according to claim 24 comprising a recessed central
region within the first circle groove.
26. A support according to claim 23 comprising from about 2 to
about 8 circle grooves.
27. A support according to claim 23 comprising from about 2 to
about 24 radius grooves.
28. A support according to claim 18 wherein the diamond-like
coating comprises at least one of the following properties: (i) a
wear factor of less than 5.times.10.sup.-6 mm.sup.3/Nm; (i) a
coefficient of friction of less than about 0.3; (ii) a hardness of
at least about 8 GPa; (iii) a resistivity of from about 10.sup.4
Ohm.multidot.cm to about 10.sup.8 Ohm.multidot.cm.
29. A substrate transport system to transport a substrate onto a
substrate support in a process chamber, the transport system
comprising: (a) a transfer arm to transport the substrate into the
chamber; (b) a detector to detect a position of the transfer arm in
the chamber and generate a signal in relation to the position; (c)
a substrate lifting assembly adapted to receive the substrate from
the transfer arm and lower the substrate onto the support; and (d)
a controller comprising program code to control the transfer arm,
detector, and lifting assembly to transport the substrate onto the
substrate support, the program code comprising: (i) substrate
centering control code to control the movement of the substrate
transfer arm to position the substrate over substantially the
center of the support by (1) receiving the signal from the detector
and determining the position of the substrate in the process
chamber, (2) calculating an offset distance comprising a difference
between the detected position of the substrate and the center of
the process chamber, and (3) generating a control signal in
relation to the offset distance to control the movement of the
transfer arm to position the substrate substantially over the
center of the support.
30. A transport system according to claim 29 wherein the process
chamber comprises a slit valve through which the substrate enters
the chamber, and wherein the detector comprises a pair of light
sensors on opposite sides of the slit valve, the light sensors
being adapted to detect radiation reflected from the substrate to
determine the position of the substrate.
31. A transport system according to claim 29 wherein the lifting
assembly comprises: (a) a hoop sized to fit about a periphery of
the substrate support; and (b) a pair of arcuate fins mounted on
the hoop, each arcuate fin comprising a pair of opposing ends
having ledges that extend radially inward, each ledge having a
raised protrusion to lift a substrate so that the substrate
contacts substantially only the raised protrusion, thereby
minimizing contact with the ledge, when the pair of fins is used to
lift the substrate off the substrate support.
32. A transport system according to claim 29 wherein the system is
adapted to transport the substrate onto a support comprising a disc
having a recessed peripheral ledge.
33. A substrate processing apparatus comprising: (a) a process
chamber comprising: (i) a gas supply; (ii) a gas energizer; (iii) a
substrate support to support the substrate in the chamber, the
support comprising a body having a disc comprising a recessed
peripheral ledge; (iv) a lifting assembly to lift a substrate from
the support, the lifting assembly comprising (1) a hoop sized to
fit about a periphery of the substrate support, and (2) a pair of
arcuate fins mounted on the hoop, each arcuate fin comprising a
pair of opposing ends having ledges that extend radially inward,
each ledge having a raised protrusion to lift a substrate so that
the substrate contacts substantially only the raised protrusion,
thereby minimizing contact with the ledge, when the pair of fins is
used to lift the substrate off the substrate support; and (v) a gas
exhaust; (b) a transfer arm to transport the substrate into the
chamber; (c) a detector to detect a position of the transfer arm in
the chamber and generate a signal in relation to the position; and
(d) a controller comprising program code to control the gas supply,
gas energizer, support, lifting assembly, transfer arm and detector
to transport the substrate into the process chamber and onto the
substrate support, wherein the program code comprises substrate
centering control code to control the movement of the substrate
transfer arm to position the substrate over substantially the
center of the support by (1) receiving the signal from the detector
and determining the position of the substrate in the process
chamber, (2) calculating an offset distance comprising a difference
between the detected position of the substrate and the center of
the process chamber, and (3) generating a control signal in
relation to the offset distance to control the movement of the
transfer arm to position the substrate substantially over the
center of the support.
34. An apparatus according to claim 33 wherein the support
comprises a diamond-like coating on the body, the diamond-like
coating comprising interlinked networks of (i) carbon and hydrogen,
and (ii) silicon and oxygen, and the diamond-like coating having a
contact surface comprising: (i) a coefficient of friction of less
than about 0.3; (ii) a hardness of at least about 8 GPa; and (iii)
a metal concentration level of less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal, whereby the contact surface reduces
contamination of a substrate when directly or indirectly contacting
a substrate.
35. An apparatus according to claim 33 wherein the support
comprises a body having a substrate receiving surface with a
pattern of grooves, the pattern of grooves comprises a plurality of
circle grooves with different radii, and a plurality of radius
grooves that extend radially across the receiving surface and
substantially only between the circle grooves.
36. A multi-chamber substrate processing apparatus comprising: (a)
a transfer chamber comprising a transfer arm to transfer a
substrate between chambers; (b) a heating chamber to heat the
substrate, the heating chamber comprising a heating pedestal to
support the substrate thereon; (c) a pre-clean chamber to clean a
substrate by exposing the substrate to an energized gas, the
pre-clean chamber comprising a pre-clean support to support the
substrate thereon; (d) a deposition chamber to deposit a material
on the substrate, the deposition chamber comprising a deposition
support to support the substrate thereon; (e) a cool-down chamber
to cool the substrate, the cool-down chamber comprising a cooling
pedestal to support the substrate thereon; (f) one or more lifting
assemblies in the chamber to raise and lower the substrate onto at
least one of the pedestals and supports; and (g) a controller
adapted to control the transfer arm and lifting assemblies to
transport the substrate into each of the chambers and place the
substrate on the pedestals and supports, wherein at least one of
the transfer arm, lifting assemblies, heating pedestal, cooling
pedestal, pre-clean support and deposition support have a coating
comprising a contamination-reducing material, and wherein a
substrate that is transferred by the transfer arm to each chamber,
raised by the lifting assemblies, and processed on the pedestals
and supports in each chamber, comprises a metal contamination level
of less than about 1.times.10.sup.11 atoms/cm.sup.2.
Description
CROSS-REFERENCE
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/786,876, entitled "Coating for Reducing
Contamination of Substrates During Processing" to Parkhe et al,
assigned to Applied Materials, Inc. and filed on Feb. 24, 2004,
which is herein incorporated by reference in its entirety.
BACKGROUND
[0002] Embodiments of the present invention relate to components
used in the transportion and support of substrates in process
chambers.
[0003] Electronic circuits of CPUs, displays and memories, are
fabricated in a process chamber by depositing or forming materials
on a substrate and then selectively etching the materials. The
substrate includes semiconductor wafers and dielectric boards. The
substrate materials are deposited or formed by processes such as
chemical vapor deposition (CVD), physical vapor deposition (PVD),
oxidation, nitridation and ion implantation. The substrate
materials are then etched to define electrical circuit lines, vias,
and other features on the substrate. A typical process chamber has
enclosure walls that enclose a substrate support, gas distributor
and exhaust port, and can also include a gas energizer to energize
process gas in the chamber by high frequency (RF) or microwave
energy.
[0004] The contact surfaces of transport and support structures
contact the substrate during its transportation and support in a
typical process cycle. Typically, a substrate is transported from a
substrate stack in a cassette within a load-lock chamber to a
process chamber on a transport blade operated by a robot arm. The
transported substrate is placed on a set of lift pins which are
lowered though holes in a substrate support to rest the backside of
the substrate on the receiving surface of a substrate support. The
substrate support can include a pedestal, a vacuum chuck having a
vacuum port to suck down the substrate, or an electrostatic chuck
comprising a dielectric covering an electrode to which a voltage is
applied to generate an electrostatic force to hold the substrate.
In some processes, the substrate is also initially transported and
rested on a degassing heater plate to degas the substrate. The
substrate may also be transferred to a cool-down pedestal to cool
the substrate after rapid thermal processing or other high
temperature processes. Shutter discs can also be used to protect
the receiving surface of a substrate support when the substrate is
not being held on the support.
[0005] The contact surfaces that contact the substrate, directly or
indirectly, can contaminate the substrate surface with contaminant
particulates. For example, stainless steel surfaces of a substrate
support pedestal, cool down plate, or degas heater, can leave
behind trace amounts of iron, chromium or copper on the backside
surfaces of the substrate. Nickel coated robotic blades can also
contaminate the substrate with residual nickel particles when they
are used to lift and transport the substrate. Similarly, aluminum
pedestals can leave behind aluminum particulates on the backside
surface of a substrate. Although the particulate contaminants are
often deposited on the inactive backside surface of the substrate,
they can diffuse to the active front side in subsequent high
temperature annealing processes, causing shorts or failure of the
circuits or displays formed on the substrate. The backside edge of
the substrate may have a particularly high number of contaminants
particles, due to abrasion of the backside edge with transport
components such as robotic transfer blades and lifting assemblies.
The contaminants can also flake off from the substrate and fall
upon and contaminate other substrates. These contaminants
eventually reduce the effective yields of circuits or displays
obtained from the substrate.
[0006] Thus, it is desirable to reduce contamination of the
backside of the substrate to increase substrate yields and process
efficiency.
SUMMARY
[0007] In yet another version, a substrate transfer arm capable of
transferring a substrate into and out of a process chamber has a
transfer blade, and a diamond-like coating on the transfer blade.
The diamond-like coating has interlinked networks of (i) carbon and
hydrogen, and (ii) silicon and oxygen, and the diamond-like coating
has a contact surface having (i) a coefficient of friction of less
than about 0.3, (ii) a hardness of at least about 8 GPa, and (iii)
a metal concentration level of less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal. The contact surface reduces contamination
of a substrate when directly or indirectly contacting a
substrate.
[0008] In another version, a support pedestal capable of reducing
particulate contamination of a substrate has a pedestal structure
having a disc with a recessed peripheral ledge, and a diamond-like
coating on the body. The diamond-like coating has interlinked
networks of (i) carbon and hydrogen, and (ii) silicon and oxygen.
The diamond-like coating has a contact surface having (i) a
coefficient of friction of less than about 0.3, (ii) a hardness of
at least about 8 GPa, and (iii) a metal concentration level of less
than about 5.times.10.sup.12 atoms/cm.sup.2 of metal. The contact
surface reduces contamination of a substrate when directly or
indirectly contacting a substrate.
[0009] In yet another version, a substrate lifting assembly is
adapted to lift a substrate from a substrate support and transports
the substrate. The lifting assembly has a hoop sized to fit about a
periphery of the substrate support, and a pair of arcuate fins
mounted on the hoop. Each arcuate fin has a pair of opposing ends
having ledges that extend radially inward, each ledge having a
raised protrusion to lift a substrate so that the substrate
contacts substantially only the raised protrusion. Thus, contact
with the ledge is minimized when the pair of fins is used to lift
the substrate off the substrate support.
[0010] In yet another version, a heat exchanging support has a body
having a substrate receiving surface with a pattern of grooves and
a diamond-like coating covering the substrate receiving surface,
the diamond-like coating having a network of carbon, hydrogen,
silicon and oxygen. The substrate receiving surface has a pattern
of grooves thereon. The heat exchanging support also has a heat
exchanger.
[0011] In yet another version, a substrate transport system
transports a substrate onto a substrate support in a process
chamber. The transport system has a transfer arm to transport the
substrate into the chamber, a detector to detect a position of the
transfer arm in the chamber and generate a signal in relation to
the position, a lifting assembly adapted to receive the substrate
from the transfer arm and lower the substrate onto the support, and
a controller having program code to control the transfer arm,
detector, and transport blade to transport the substrate onto the
substrate support. The program code has substrate centering control
code to control the movement of the substrate transfer arm to
position the substrate over substantially the center of the support
by (1) receiving the signal from the detector and determining the
position of the substrate in the process chamber, (2) calculating
an offset distance comprising a difference between the detected
position of the substrate and the center of the process chamber,
and (3) generating a control signal in relation to the offset
distance to control the movement of the transfer arm to position
the substrate substantially over the center of the support.
[0012] In yet another version, a substrate processing apparatus has
a process chamber having a gas supply, a gas energizer, a substrate
support to support the substrate in the chamber, the support having
a body with a disc having a recessed peripheral ledge, a gas
exhaust, and a lifting assembly to lift a substrate from the
support. The lifting assembly has (1) a hoop sized to fit about a
periphery of the substrate support, and (2) a pair of arcuate fins
mounted on the hoop, each arcuate fin having a pair of opposing
ends having ledges that extend radially inward, each ledge having a
raised protrusion to lift a substrate so that the substrate
contacts substantially only the raised protrusion, thereby
minimizing contact with the ledge, when the pair of fins is used to
lift the substrate off the substrate support. The apparatus also
has a transfer arm to transport the substrate into the chamber, a
detector to detect a position of the transfer arm in the chamber
and generate a signal in relation to the position, and a controller
comprising program code to control the gas supply, gas energizer,
support, lifting assembly, transfer arm and detector to transport
the substrate into the process chamber and onto the substrate
support. The program code has substrate centering control code to
control the movement of the substrate transfer arm to position the
substrate over substantially the center of the support by (1)
receiving the signal from the detector and determining the position
of the substrate in the process chamber, (2) calculating an offset
distance comprising a difference between the detected position of
the substrate and the center of the process chamber, and (3)
generating a control signal in relation to the offset distance to
control the movement of the transfer arm to position the substrate
substantially over the center of the support.
[0013] In still another version, a multi-chamber substrate
processing apparatus has (i) a transfer chamber having a transfer
arm to transfer a substrate between chambers, (ii) a heating
chamber to heat the substrate, the heating chamber having a heating
pedestal to support the substrate thereon, (iii) a pre-clean
chamber to clean a substrate by exposing the substrate to an
energized gas, the pre-clean chamber having a pre-clean support to
support the substrate thereon, (iv) a deposition chamber to deposit
a material on the substrate, the deposition chamber having a
deposition support to support the substrate thereon, (v) a
cool-down chamber to cool the substrate, the cool-down chamber
having a cooling pedestal to support the substrate thereon, (vi)
one or more lifting assemblies in the chamber to raise and lower
the substrate onto at least one of the pedestals and supports, and
(vii) a controller adapted to control the transfer arm and lifting
assemblies to transport the substrate into each of the chambers and
place the substrate on the pedestals and supports. At least one of
the transfer arm, lifting assemblies, heating pedestal, cooling
pedestal, pre-clean support and deposition support have a coating
having a contamination-reducing material. A substrate that is
transferred by the transfer arm to each chamber, raised by the
lifting assemblies, and processed on the pedestals and supports in
each chamber, has a metal contamination level of less than about
1.times.10.sup.11 atoms/cm.sup.2.
DRAWINGS
[0014] These features, aspects, and advantages of the present
invention will become better understood with regard to the
following description, appended claims, and accompanying drawings,
which illustrate examples of the invention. However, it is to be
understood that each of the features can be used in the invention
in general, not merely in the context of the particular drawings,
and the invention includes any combination of these features,
where:
[0015] FIG. 1 is a sectional side view of an embodiment of a
substrate support having a plurality of mesas comprising a
contamination reducing coating;
[0016] FIG. 2a is a sectional side view of an embodiment of a
heating pedestal having a contamination reducing coating;
[0017] FIG. 2b is a sectional side view of an embodiment of a
cooling pedestal with a contamination reducing coating;
[0018] FIG. 3 is a sectional side view of an embodiment of a lift
pin assembly having lift pins with a contamination reducing
coating;
[0019] FIG. 4 is a sectional side view of an embodiment of a
shutter having a contamination reducing coating;
[0020] FIG. 5 is a sectional side view of an embodiment of a
component having a protective cap comprising a base layer covered
by a contamination reducing coating;
[0021] FIG. 6 is a sectional top view of an embodiment of
multi-chamber apparatus;
[0022] FIG. 7a is a sectional side view of an embodiment of a
component processing chamber;
[0023] FIG. 7b is a sectional side view of an embodiment of a
substrate processing chamber;
[0024] FIG. 8 is a top view of an embodiment of a support having a
pattern of grooves formed therein;
[0025] FIG. 9a is top view of an embodiment of a support having a
recessed peripheral ledge;
[0026] FIG. 9b is a sectional side view of an embodiment of the
support of FIG. 9a having a substrate thereon;
[0027] FIG. 10a is a side view of an embodiment of a lifting
assembly having arcuate fins, and a support having a pattern of
grooves;
[0028] FIG. 10b is a top view of an embodiment of an arcuate fin
from the lifting assembly of FIG. 10a; and
[0029] FIG. 11 is a side view of an embodiment of a transport
system having a detector to detect a position of a substrate.
DESCRIPTION
[0030] In the substrate processing methods, substrates 104 are
transported and held by various support components 20. For example,
a substrate 104 may be held during processing in a chamber 106 on a
support component 20 that is a substrate support 100, and which has
an a support structure 25 that can also serve as an electrostatic
chuck 102 as shown in FIG. 1. The substrate 104 may also be
supported by a support component 20 comprising a support structure
25 that is a heat exchange pedestal 150, such as a heating pedestal
151 or cooling pedestal 152, as illustrated in FIGS. 2a and 2b,
that is used to degas a substrate 104 by heating it, or to cool a
substrate 104 after a high temperature process. Further types of
support components 20 include support structures 25 suitable for
transporting the substrate, such as lift pins 160 as shown in FIG.
3, and robotic arms having robot blades, can be used to place and
remove substrates 104 on supports 100, as well as to transfer
substrates 104 between chambers 106 in a multi-chamber apparatus
101. Yet another support component 20 is a support shutter 180, as
shown in FIG. 4, to cover a portion of the substrate support 100
when the substrate 104 is not present during a chamber cleaning
process. It should be understood that the various embodiments of
support components 20 that are described herein are provided to
illustrate the invention, and should not be used to limit the scope
of the present invention, and that other versions of support
components apparent to those of ordinary skill are also within the
scope of the present invention.
[0031] The processing yields of substrates 104 is substantially
improved with support components 20 having contact surfaces 22
capable of reducing, and even eliminating, the formation and/or
deposition of contaminant residues that arise from frictional and
abrasive forces between the contact surface 22 of the support
component 20 and the substrate 104. For example, when the component
20 is made from a metal containing material, metal contaminant
particles deposit on the substrate 104 when the substrate 104 rubs
against the contact surface 22 of the support component 20. It has
been found that the frictional residues have larger particle sizes
or numbers, when the contact surface 22 is excessively soft, has a
high frictional coefficient causing abrasion of the surfaces, or
has a high level of impurities. To reduce such contamination, the
contact surfaces 22 of the support component 20 are provided with a
surface coating 24 that has desirable abrasion or hardness,
frictional properties, and/or low-levels of contaminants. The
contact surfaces 22 comprising the coating 24 desirably reduce the
contamination of substrates 104 when directly or even indirectly
contacting the substrates 104. For example, a support shutter 180
having the contact surface 22 on the contamination reducing coating
24 may indirectly reduce the contamination of substrates 104 by
reducing the contamination of a support surface 28 on which
substrates 104 are placed. The contamination reducing coating 24
may cover at least a portion of a surface 26 of a component
structure 25, as shown for example in FIG. 2a, or may even cover
substantially the entire surface that is in contact with the
substrate 104. The coating 24 is also sufficiently thick to protect
the substrate 104 from contamination by the underlying support
structure, for example the coating 24 may comprise a thickness of
at least about 0.02 microns, such as from about 0.02 microns to
about 1000 microns, and even about 0.02 microns to about 20
microns, such as from about 1 to about 20 microns, and even about
1.5 microns. The coating thickness may also be selected to provide
good resistance to wearing of the coating by contact with the
substrate 104.
[0032] In one version, the contamination reducing coating comprises
a material having a coefficient of friction that is sufficiently
low to reduce the formation and deposition of friction or abrasion
resulting particulates on the substrate 104. The low-friction
material can improve substrate processing yields by contacting the
substrate 104 only with a low-friction material that is less likely
to flake or "rub-off" the surface 22 and deposit onto the substrate
104. The low-friction material suitable for the surface 22
desirably comprises a coefficient of friction of less than about
0.3, such as from about 0.05 to about 0.2. The coefficient of
friction is the ratio of the limiting frictional force to the
normal contact force when moving the surface 22 relative to another
surface. By comparison, a supporting surface of a heating pedestal
151 made of stainless steel, and without the aforementioned
coating, can have a coefficient of friction of at least about 0.7.
The contamination reducing coating further comprises a low average
surface roughness, such as for example, an average surface
roughness of less than about 0.4 micrometers. The lower surface
roughness makes the contact surface 22 of the coating less likely
to catch or tear out the substrate 104 when the substrate is
transferred onto or off the contact surface 22.
[0033] The contamination reducing coating also desirably has a high
hardness to provide better resistance to scratching and abrasion by
the substrate 104. When the substrate is a relatively hard
material, it is desirable for the contact surface 22 to also be
composed of a material having a relatively high hardness to be less
likely to generate loose particles or flakes due to scratching of
the surface 22. A suitable contamination reducing coating may
comprise a hardness of at least about 8 GPa, such as from about 8
Gpa to about 25 Gpa, and even at least about 10 GPa, such as from
about 18 Gpa to about 25 GPa. The surface 22 desirably comprises a
hardness that is selected with respect to the substrate 104 being
processed. For example, the surface 22 of a component for
processing a substrate 104 comprising a semiconductor wafer may
have a hardness that is different than the hardness of a surface 22
for processing a substrate 104 comprising a dielectric glass panel
used for displays.
[0034] The hardness of the surface 22 can be measured by, for
example, a hardness load and displacement indentation test. A
suitable instrument for performing the hardness test may be, for
example, a "Nano Indenter II" available from Nano Instruments, Inc.
in Oak Ridge, Tenn. In this test, the tip of an indenter probe is
placed against the surface 22, and a load is applied to the
indenter probe that presses the tip into the surface 22 and forms
an indentation in the surface 22. The tip of the indenter probe can
be, for example, pyramidal shaped, and a suitable load may be in
the microgram range. The hardness of the surface 22 can be found by
evaluating the indentation, for example, by taking a ratio of the
force applied to the indenter probe divided by the area of the
indentation that results from the force, as described for example
in Review of Instrumented Indentation in the Journal of Research of
the National Institute of Standards and Technology, Vol. 108, No.
4, July-August 2003, which is herein incorporated by reference in
its entirety. The area of the indentation can be calculated, for
example, optically or by monitoring a depth of the indenter probe
in the surface and using a known geometry of the tip of the
indenter probe.
[0035] It is further desirable for the contact surface 22 to have
low levels of contamination-reducing metals that have a high purity
with a low concentration of impurities, especially metal impurities
such as Fe, Cr, Ni, Co, Ti, W, Zn, Cu, Mn, Al, Na, Ca, K and B. The
metal impurities can rub off on and migrate from the surfaces of
supporting components and into the substrates to contaminate the
substrates. Suitable contamination reducing coatings have a metal
concentration level of less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal atoms at the surface 22 of the coating, or
even less than about 5.times.10.sup.10 atoms/cm.sup.2 of metal
atoms. The contamination-reducing material is also desirably
resistant to corrosion by energized process gases. While a coating
comprising a ceramic material having the desired low levels of
metal atoms can be applied to a metal or ceramic support structure
to reduce its contaminating effect on a substrate, the surface of a
ceramic support component, such as ceramic electrostatic chuck
having an embedded electrode can also be treated to clean the
surface to reduce the contaminant levels of the surface.
[0036] The contamination reducing coating 24 can also be tailored
to have provide good adhesion to the underlying support structure
25 by controlling, for example, the coating thickness, coefficient
of thermal expansion, or tensile strength. For example, the coating
24 comprising the contamination reducing coating desirably
comprises a thermal coefficient of expansion that is sufficiently
matched to the expansion coefficient of the underlying component 22
to reduce cracking or spalling of the coating 24 from the component
22. A coefficient that is too high or too low can result in
cracking and de-lamination of the coating 24 from the structure as
a result of unequal expansion/contraction rates of the coating and
underlying structure materials during heating or cooling of the
component 22. The thickness of the coating 24 can also affect the
adhesion of the coating 24. For example, for an underlying
structure comprising aluminum nitride, a suitable coating 24
comprising the contamination reducing coating may comprise a
coefficient of thermal expansion of from about 4 ppm to about 6 ppm
per degree Celsius. For an underlying structure comprising a metal
such as aluminum or stainless steel, a suitable coating 24 of
contamination reducing coating may comprise a similar coefficient
of thermal expansion of from about 4 ppm to about 6 ppm, and may
also comprise a reduced thickness to inhibit spalling of the
coating 24.
[0037] In one version, the contamination-reducing material
comprises a diamond-like material, such a diamond-like carbon (also
referred to as DLC.) Diamond-like materials are carbon-based
materials with a network of carbon and hydrogen atoms. They
typically have a significant fraction of sp.sup.3 hybridized
carbon, such as at least about 50% sp.sup.3 hybridized carbon to at
least about 98% sp.sup.3 hybridized carbon. Thus, many of the
carbon atoms in the network are be bonded to other carbon or
hydrogen atoms in several directions, similar to diamond, as
opposed to being substantially limited to bonding to atoms that are
in the same plane, as in graphite. However, the bonded carbon atoms
have only a short range order in the form of micro-crystals or
crystallites, and typically do not form a full three-dimensional
crystalline lattice of diamond having a long range order. Depending
on the fabrication conditions, the diamond-like materials can be
amorphous or can contain crystallites with nanoscale sizes. The
diamond-like materials can also contain a significant amount of
hydrogen, such as a content of at least about 2 atom % of hydrogen,
for example from about 2 atom % to about 25 atom % of hydrogen.
Diamond-like carbon (DLC) also has a high hardness and a low
coefficient of friction that can reduce the contamination of
substrates 104 from surfaces 22 having the materials. For example,
the diamond-like carbon material can have a hardness of at least
about 18 GPa, such as from about 18 GPa to about 25 GPa. The
coefficient of friction of the surface of the diamond-like carbon
is also desirably low, such as a coefficient of less than about
0.3, such as from about 0.05 to about 0.2. The diamond-like carbon
material can also comprise a low surface roughness, such as an
average surface roughness of less than about 0.4 micrometers, such
as from about 0.05 to about 0.4 micrometers. The diamond
like-carbon can also be manufactured with a low amount of metal
impurities, such as less than about 5.times.10.sup.12
atoms/cm.sup.2 of metal impurities, and even less than about
5.times.10.sup.11 atoms/cm.sup.2 of metal atoms. For example, the
material can comprise a concentration of titanium atoms of less
than about 10 atom %, and even less than about 6 atom % of
titanium. Thus, diamond-like materials such as diamond-like carbon
provide characteristics such as a low coefficient of friction, high
hardness and high purity that are desirable for
contamination-reducing materials on surfaces 22.
[0038] In one version, the diamond-like carbon materials are formed
as coatings 24 over underlying components surfaces 26 to provide a
metal contamination reducing component surface. A coating 24 of the
diamond-like carbon materials can be formed by methods including
chemical vapor deposition, carbon ion beam deposition, ion-assisted
sputtering from graphite and laser ablation of graphite. An example
of a method of depositing a diamond-like carbon coating layer by a
chemical vapor deposition method is described in U.S. Pat. No.
6,228,471 to Neerinck et al, PCT filed Jan. 23, 1998, assigned to
N. V. Bekaert S. A., which is herein incorporated by reference in
its entirety. The fabrication process can be controlled to tailor
the properties of the resulting coating. For example, the
fabrication conditions can be controlled to tailor the amount of
hydrogen incorporated into the coating 24. Also, the fabrication
conditions can be controlled to tailor the electrical properties of
the coating 24, for example to provide electrical properties that
may be desirable for an electrostatic chuck 102. For example, the
electrical resistivity of the coating 24 can be controlled by
controlling the proportion of sp.sup.3 to sp.sup.2 hybridized
carbon atoms. A higher proportion of sp.sup.3 hybridized carbon
atoms gives a higher resistivity, while a higher proportion of
sp.sup.2 hybridized carbon atoms gives a lower resistivity.
[0039] In another version, the contamination reducing coating can
comprise a diamond-like material comprising a diamond-like
nanocomposite having both (i) networks of carbon and hydrogen, and
(ii) networks of silicon and oxygen. The diamond-like nanocomposite
is similar to the diamond like carbon, in that it comprises a
network of bonded carbon atoms of which a substantial fraction are
sp.sup.3 hybridized but does not have a substantially long-range
order as in pure diamond, and can further comprise bonded hydrogen
atoms. Depending on the fabrication conditions, the diamond-like
nanocomposite can be fully amorphous or can contain diamond
crystallites, for example, at the nanoscale level. The diamond-like
nanocomposite comprises a networks of silicon bonded oxygen that
interpenetrate the carbon networks in a substantially random
fashion, to form a composite material having high temperature
stability, high hardness and a low coefficient of friction. The
percentage of each of C, H, Si and O atom in the nanocomposite can
be selected to provide the desired composition characteristics. A
suitable diamond-like nanocomposite may comprise a composition of,
for example, from about 50 atom % to about 90 atom % carbon, from
about 5 atom % to about 10 atom % hydrogen, from about 10 atom % to
about 20 atom % silicon and from about 5 atom % to about 10 atom %
oxygen. The diamond-like nanocomposites may comprise a low
coefficient of friction of less than about 0.3, such as from about
0.05 to about 0.2, and a low average surface roughness of less than
about 0.4 micrometers, such as from about 0.05 micrometers to about
0.4 micrometers, and even less than about 0.1 micrometers. The
diamond-like nanocomposite may also comprise a microhardness of at
least about 8 GPa, such as from about 8 to about 18 GPa. The
diamond-like nanocomposite may also comprise a high purity, for
example, the diamond-like nanocomposite can comprise less than
about 5.times.10.sup.12 atoms/cm.sup.2 and even less than about
5.times.10.sup.11 atoms/cm.sup.2 of metal impurities. For example,
the material can comprise less than about 10 atom % of metal
impurities such as titanium, and even less than about 7 atom % of
titanium.
[0040] In one version, a coating 24 comprising the diamond-like
carbon materials may further comprise a wear factor that provides
reduced wear of the coating 24 when used to process substrates 104.
The wear factor is a measure of the amount of wear experienced by a
surface when slid or rubbed along another surface. The wear factor
can be obtained, for example, by sliding the surface against a
reference surface and measuring the slope of the volume loss of a
linear region versus the sliding distance, typically while
maintaining the normal load and sliding speed constant. A suitable
wear factor for a coating 24 comprising a diamond like
nanocomposite may be, for example, less than about
5.times.10.sup.-6 mm.sup.3/Nm.
[0041] The diamond-like nanocomposite can be formed by methods
similar to those described for diamond-like carbon materials,
including by a chemical vapor deposition method, and can be formed
as a coating 24 on the component 20. Examples of methods of forming
diamond-like nanocomposite coatings is described, for example, in
U.S. Pat. No. 5,352,493 to Dorfman et al, filed Oct. 4, 1994,
assigned to Veniamin Dorfman, and U.S. Pat. No. 6,228,471 to
Neerinck et al, PCT filed Jan. 23, 1998, assigned to N. V. Bekaert
S. A., both of which are herein incorporated by reference in their
entireties. The diamond-like nanocomposite material can also be
commercially available materials such as DLN or Dylyn.RTM. from
Bekaert Advanced Coating Technologies, Belgium.
[0042] The diamond-like materials, including diamond-like carbon
and diamond-like nanocomposites, can also be tailored by
incorporating metal additives into the materials. The metal
additives can be added to provide desired properties, such as a
desired electrical resistivity or conductance of the material. The
metal additives are distributed about the diamond-like material,
and may even form a separate bonded metal network that
interpenetrates at least one of the carbon and a silicon networks.
Suitable metal additives may comprise, for example, at least one of
B, Li, N, Si, Ge, Te, Mo, W, Ta, Nb, Pd, Ir, Pt, V, Fe, Co, Mg, Mn,
Ni, Ti, Zr, Cr, Re, Hf, Cu, Ag and Au. The diamond-like material
can comprise from about 0.1 atom % to about 10 atom % of the metal
additive, such as for example, titanium. The diamond-like material
having the metal additives also comprises a relatively low
coefficient of friction and relatively high hardness. For example a
diamond-like nanocomposite comprising C:H and Si:O networks having
metal additives can comprise a coefficient of friction of less than
about 0.3, such as from about 0.05 to about 0.2. The diamond-like
nanocomposite with metal additives can also have a microhardness of
at least about 12 GPa, such as from about 12 to about 18 GPa. The
metal additives can be introduced into the diamond-like networks by
co-depositing the metals with the diamond-like material, or by
another suitable fabrication method. Examples of metal additive
incorporation methods are described in U.S. Pat. Nos. 5,352,493 and
6,228,471, which are incorporated by reference in their entireties
above.
[0043] In one version of a method of forming a coating 24
comprising a diamond like material, a component structure 25 is
placed in a plasma zone 213 of a process chamber, and embodiment of
which is shown in FIG. 7a. The chamber 106 comprises chamber walls
218 enclosing the plasma zone 213. The component 20 can be held on
a support 202 in the chamber 106. A process gas supply 130 provides
a deposition gas into the chamber 106, and can comprise a gas
source, one or more conduits leading from the source to the
chamber, flow meters, and one or more gas inlets in the chamber
106. The process gas comprises at least a carbon-containing
compound, such as a carbon-containing gas, that is capable of
forming bonded carbon networks in the coating 24. The process gas
can also comprise a hydrogen-containing compound, such as a
hydrogen-containing gas. For example, the process gas can comprise
a gas comprising both carbon and hydrogen atoms, such as at least
one of methane, propane, acetylene, butane and ethelyne. To form a
diamond like nanocomposite comprising a network of silicon and
oxygen, the process gas can further comprise a silicon-containing
compound. For example, the process gas can comprise
hexamethyldisiloxane or polyphenylmethylsiloxane, as described for
example in U.S. Pat. No. 5,638,251 to Goel et al, filed on Oct. 3,
1995 and assigned to Advanced Refractory Technologies, which is
herein incorporated by reference in its entirety. The process gas
can further comprise an additive gas, such as for example
argon.
[0044] A gas energizer 216 energizes the process gas to form an
energized gas in the process zone 213 that deposits a diamond like
material on the component surface 26 by plasma enhanced chemical
vapor deposition. For example, the gas energizer 216 can decompose
a process gas comprising carbon, hydrogen, silicon and oxygen
containing compounds to deposit a chemical vapor deposition
material comprising a diamond like nanocomposite on the surface 26.
The gas energizer 216 can comprise, for example, one or more of an
inductor antenna and electrodes that are capable of coupling RF
energy to form the energized gas. An exhaust 220 can be provided to
exhaust gases from the chamber, and can comprise an exhaust port
leading to an exhaust pump, and a throttle valve to control the
pressure in the chamber 106. A controller 294 can controls the
components of the chamber 106 to deposit the coating 24 on the
component 20.
[0045] In one version, the chamber 106 comprises a target 214
having a metal material that can be sputtered from the target 214
by the energized gas to co-deposit the sputtered metal on the
surface 26 simultaneously with the chemical vapor deposited
material, to form a diamond like material having a metal additive.
In this version, the diamond-like material is co-deposited with the
metal additive by a process combining physical vapor deposition of
the metal additive in the plasma enhanced chemical vapor deposition
environment. The target 214 can comprise a metal material
comprising, for example, at least one of titanium and tungsten. In
one version, the target 214 acts as a part of the gas energizer 216
and can be electrically biased to induce sputtering of the target
material. A magnetron 217 comprising a magnetic field generator can
also be provided as a part of the gas energizer 216. A power
applied to the magnetron 217 can energize and maintain a density of
the gas to sputter material from the target 214. The metal material
can also be co-deposited in the coating 24 by methods other than
sputtering, such as for example by thermal evaporation of a metal
source, or by a metal ion beam.
[0046] In one version, a component 20 comprising the coating 24
having the diamond-like material can be refurbished, for example in
the chamber embodiment shown in FIG. 7a, after processing a number
of substrates 104. The coating 24 can be refurbished to repair or
replace portions of the coating 24 that may have eroded during
substrate processing, for example by exposure to an energized gas.
A cleaning step may also be performed to remove any residual
coating from the surface 26. For example, the surface may be
cleaned with a chemical solution that dissolves the coating, or the
coating can be grit blasted from the surface 26. In another version
of a cleaning process, the residual coating can be removed by a
reactive ion etching process in which the residual coating is
exposed to an energized etching gas to etch away the remaining
coating 24. In the refurbishment process, a coating 24 comprising
the diamond-like material is re-deposited on the surface 26 of the
component 20, for example by the method described above, including
by co-depositing a chemical vapor deposition material
simultaneously with a sputtered metal.
[0047] In yet another version, a coating 24 comprising a
diamond-like nanocomposite comprising C:H and Si:O networks can be
treated to seal the surface 22 of the coating 24. For example, the
surface 22 of the coating 24 can be exposed to an oxygen-containing
reactant, such as water vapor, that reacts with carbon atoms in the
diamond-like material to form gaseous products, such as for example
CO and CO.sub.2. The gaseous products leave the surface 22,
providing a "densified" diamond-like surface material having a
higher silicon content and a reduced amount of carbon. For example,
the surface 22 of the coating 24 may comprise at least about 90
atom % of Si and O. The "densified" surface 22 acts as a sealant
against further moisture, and provides improved processing
performance of the component having the coating 24.
[0048] In another version, the contamination reducing coating
comprises a high-purity ceramic having characteristics that reduces
the contamination of substrates 104 from surfaces 22 having the
high-purity material. In one version, the contamination-reducing
material comprising the high-purity ceramic comprises high-purity
silicon carbide. The contamination-reducing silicon carbide
material comprises a purity of at least about 99% and even at least
about 99.999%, and can comprise less than about 5.times.10.sup.12
atoms/cm.sup.2 to less than about 5.times.10.sup.9 atoms/cm.sup.2
of metal atoms, such as less than about 5.times.10.sup.10 atoms of
metal atoms per cm.sup.2. The silicon carbide material also
desirably comprises a high density, such as a density of from about
98% to about 100% of the theoretical density, such as at least
about 99% of the theoretical density. The surface 22 comprising the
metal contamination reducing silicon carbide material can also be
polished to provide a low coefficient of friction of less than
about 0.3, such as from about 0.05 to about 0.2, and can provide a
substantially smooth surface having a low surface roughness, such
as an average surface roughness of less than about 0.2
micrometers.
[0049] Suitable contamination-reducing silicon carbide materials
can be fabricated by, for example, a high purity silicon carbide
sintering method, as described for example by U.S. Pat. No.
6,001,756 to Takahashi et al, filed on May 9, 1997 and assigned to
Bridgestone Corporation, which is herein incorporated by reference
in its entirety. For example, the contamination-reducing silicon
carbide material can comprise a coating 24 having a layer of
high-purity sintered silicon carbide. Also, a coating of high
purity silicon carbide can be deposited onto the surface 26 of a
component 20, for example by a chemical vapor deposition method
which reacts carbon and silicon-containing precursors to form a
deposited silicon carbide coating. A coating 24 can also be formed
by, for example, thermochemical conversion of a carbonaceous
material, such as graphite, with a reactant containing silicon, an
example of which conversion is described in U.S. Pat. No. 5,705,262
to Bou et al., filed on Oct. 26, 1994, and assigned to Le Carbone
Lorraine, which is herein incorporated by reference in its
entirety.
[0050] In another version, a contamination reducing material
comprises a high-purity ceramic comprising silicon nitride. The
high-purity silicon nitride material may have the desired
contamination-reducing characteristics, such as less than about
5.times.10.sup.12 atoms/cm.sup.2 of contaminate metals, and even
less than about 5.times.10.sup.10 atoms/cm.sup.2 of contaminate
metals. The silicon nitride material may also have a density of
from about 98% of the theoretical density to about 100% of the
theoretical density, such as at least about 99% of the theoretical
density. The high-purity silicon nitride material may have a
coefficient of friction of less than about 0.3, such as from about
0.05 to about 0.2, and a hardness of from about 10 GPa to about 18
GPa, such as at least about 16 GPa. Furthermore, the silicon
nitride surface may be polished to provide a surface roughness
average of less than about 0.4 micrometers. Also, a coating 24
comprising the metal contamination-reducing Si.sub.3N.sub.4 can
exhibit good adhesion to metal surfaces such as stainless steel
even at temperatures of at least about 550.degree.. The surface 22
comprising the silicon nitride may comprise a silicon nitride
coating 24, such as for example a coating 24 formed by a chemical
vapor deposition process.
[0051] Other high-purity ceramic materials that may serve as
contamination reducing coatings can comprise, for example, at least
one of silicon and silicon oxide. The silicon and silicon oxide
materials have a high purity with less than about 5.times.10.sup.12
contaminant metals per cm.sup.2. The materials are also desirably
polished to provide the desired coefficient of friction of less
than about 0.3, and an average surface roughness of less than about
0.4 micrometers.
[0052] In one version, a coating 24 comprising a contamination
reducing coating can coat a base layer 130 that covers a surface 26
of a component 20 to form a protective cap 133, as shown for
example in FIG. 5. The cap 133 provides protection of the
underlying component structure 25, while providing a contamination
reducing surface 22 that reduces contamination of substrates 104.
The cap 133 can also comprise a conformal ledge 136 that covers a
peripheral edge 137 of the underlying structure 25 to protect the
structure 25. In one version, the cap 133 comprises a coating 24
having a high-purity silicon carbide layer that is formed over the
graphite base layer 130, for example by chemical vapor deposition
or thermochemical conversion of the surface of the graphite base
layer 130, to provide a coating surface 22 having the
contamination-reducing materials. In another version, the cap 133
comprises a base layer 130 comprising a metal infiltrated silicon
carbide material that is coated by a high-purity silicon carbide
coating 24. The infiltrated silicon carbide base layer 130 is
formed by infiltrating the pores of a porous sintered silicon
carbide material with a metal, such as silicon metal. For example,
the silicon metal can be infiltrated to provide a volume percent of
from about 20% to about 80% of the base layer material. A coating
24 comprising silicon carbide is formed over the base 130
comprising the infiltrated silicon carbide material by, for
example, chemical vapor deposition, to form a high purity silicon
carbide layer that reduces contamination. Alternatively, the cap
133 may be substantially entirely made from silicon carbide, such
as sintered silicon carbide, to form the coating 24, or may have a
sintered silicon carbide base layer 130 covered by a silicon
carbide coating 24.
[0053] In one version, the cap 133 comprises a base layer 130 that
is substantially entirely covered by the coating 24, as shown for
example in FIG. 5. In this version, the coating 24 can cover a top
surface 131, bottom surface 134 and even a side surface 135 of the
base layer 130. Providing such a coating 24 can be beneficial
because thermal stresses that can develop between the coating 24
and base layer 130 can be reduced. For example, during a cooling
step performed after applying the coating 24 by a chemical vapor
deposition method, differences in the thermal expansion coefficient
of the coating 24 and base layer 130 can cause stresses that could
induce bowing or other deformation of the coating surface 22. By
applying the coating 24 to the bottom surface 134 of the base layer
130 as well as the top surface 131, the stresses at the top surface
131 can be at least in part compensated for, to even out the
stresses at the top and bottom surfaces 131,134 and reduce the
deformation of the coating surface 22.
[0054] In one version, an adhesion layer 140 is provided to secure
the coating 24 comprising the contamination-reducing material to
the underlying component structure. For example, as shown in FIGS.
1 and 2, the adhesion layer 140 may be applied to the upper surface
26 of the component 22, and the coating 24 may be formed thereover
to adhere the coating 24 to the surface 26. For example the
adhesion layer 140 can comprise at least one of titanium, aluminum,
zirconium and chromium. In one version, the adhesion layer 140
comprises a metal such as titanium that bonds well to both metal
and non-metallic materials. The adhesion layer 140 can comprise a
thickness of, for example, from about 0.25 to about 4 microns. The
coating 24 and the cap 133 can also be mechanically affixed to the
underlying component structure 25, for example with connector
pins.
[0055] In one version, a component 20 having the contamination
reducing material comprises a support structure 25 comprising a
substrate support 100 having an electrostatic chuck 102, and
embodiment of which is shown in FIG. 1. The electrostatic chuck 102
comprises an electrode 108 at least partially covered by a
dielectric body 109, and may even be substantially entirely covered
by the dielectric body 109. The electrode 108 is chargeable by a
voltage supply to electrostatically hold a substrate 104 on the
chuck 102. In one version, the dielectric body 109 comprises a
dielectric material having a relatively low resistivity of below
about 10.sup.12 Ohms.multidot.cm, such as for example at least one
of aluminum nitride, and boron nitride. The relatively
low-resistivity dielectric body can promote a Johnson-Rahbek effect
to hold the substrate on the chuck 102, by allowing electric charge
to at least partially migrate through the dielectric body 109 to
hold the substrate 104. Other low-resistivity dielectric materials
suitable for the dielectric body can include, for example, aluminum
oxide doped with at least one of titanium oxide and chromium
oxide.
[0056] The electrostatic chuck 102 comprises a plurality of mesas
112 on an upper surface 26 of the dielectric body 109 that support
the substrate 104. The plurality of mesas 112 can be shaped and
distributed to provide an optimum electrostatic chucking force, and
can also provide a desired heat transfer gas flow distribution to
upper surface of the dielectric body. For example, the mesas 112
can be arranged in spaced-apart, concentric rings on the upper
surface 26. The composition of the mesas 112, as well as the height
and width of the mesas 112, can also be selected to provide the
desired electrostatic chucking force. For example, the mesas 112
can comprise a dielectric material having a relatively high
resistivity, to form a hybrid Johnson-Rahbek electrostatic chuck.
An example of a hybrid Johnson-Rahbek electrostatic chuck having
supporting mesas 112 is described in U.S. Pat. No. 5,903,428 to
Grimard et al, filed on Sep. 25, 1997 and commonly assigned to
Applied Materials, which is herein incorporated by reference in its
entirety. The mesas 112 can also comprise a conductive material
such as a metal-containing material with low resistivity, such as a
TiAIN material as described for example in Taiwan Patent No.
0466667 to Tsai, filed on Jun. 29, 2000 and commonly assigned to
Applied Materials, which is herein incorporated by reference in its
entirety.
[0057] In one version, the mesas 112 comprise a coating 24 having
at least one of the contamination-reducing materials described
above. For example, substantially the entire mesa 112 can comprise
the coating 24 formed from a contamination-reducing material. A
suitable height of mesas 112 that substantially entirely comprise
the contamination-reducing material may be from about 0.25
micrometers to about 6 micrometers. Alternatively, the mesa 112 can
comprise a surface coating 24 of the contamination-reducing
material that overlies the rest of the mesa 112. The mesas 112 can
comprise a contamination-reducing material comprising at least one
of a diamond like material, such as for example diamond-like
carbon, a diamond-like nanocomposite, and a metal-containing
diamond-like material. The mesas 112 can also comprise a
contamination-reducing material comprising a high-purity ceramic,
such as at least one of the silicon carbide, silicon nitride,
silicon and silicon oxide materials described above. The mesas 112
can also comprise an adhesion layer 140, for example comprising
titanium, that improves adhesion of the coating 24.
[0058] In one version, the mesas 112 comprise a diamond-like
material, such as diamond-like carbon or a diamond-like
nanocomposite material, that is tailored to provide a desired
resistivity, such as a resistivity of from about 10.sup.2
Ohms.multidot.cm to about 10.sup.10 Ohms.multidot.cm. For example,
the mesas 112 may comprise a diamond-like material having the
proportion of sp2 hybridized carbon atoms selected to provide an
electrical resistivity of the mesa 112 of from about 10.sup.4
Ohms.multidot.cm to about 108 Ohms.multidot.cm, such as a percent
of sp2 hybridized carbon atoms of from about 5% to about 10%. As
another example, the concentration of metal additive in the
diamond-like material can be varied to provide the desired
resistivity of the material. For example, a suitable diamond-like
material may comprise from about 1 to about 10 atom % of a metal
additive such as titanium, to provide a resistivity of from about
10.sup.4 to about 10.sup.8 Ohm.multidot.cm, such as about 10.sup.6
Ohm.multidot.cm.
[0059] In another version, the mesas 112 comprise a high-purity
ceramic, such as at least one of silicon carbide, silicon nitride,
silicon and silicon oxide, and the surface 22 of the mesas 112 can
be polished to provide a low average surface roughness, to reduce
contamination of the substrate 104 from the surface. The average
surface roughness of the mesa surface 22 can be relatively low, as
the electrostatic chucking force holds the substrate 104 on the
support 100. For example, the surface 22 of the mesas 112
comprising the high-purity ceramic, such as for example silicon
nitride, may comprise an average surface roughness of less than
about less than about 0.4 micrometers, and even less than about 0.1
micrometers.
[0060] In another version, a component 20 comprising the
contamination-reducing material comprises a support structure 25
comprising a heat exchange pedestal 150, such as for example a
heating pedestal 151, an embodiment of which is shown in FIG. 2a,
or a cooling pedestal 152, an embodiment of which is shown in FIG.
2b. The heat exchange pedestal is adapted to exchange heat with the
substrate 104 to provide a desired temperature of the substrate
104. For example, a heating pedestal 151 may heat a substrate 104
to remove or de-gas contaminant materials from the substrate 104
before processing of the substrate. The cooling pedestal 152 may
cool the substrate 104 to a desired temperature, such as a
temperature that is suitable for handling the substrate after
processing. The heat exchange pedestal 150 comprises a thermally
conductive pedestal body 154 adapted to exchange heat with the
substrate 104, and a receiving surface 22 to receive a substrate.
The heat exchange pedestal 150 further comprises a heat exchanger
157 comprising at least on of a heater 155 and conduits 158 through
which a heat exchange fluid can be flowed. In one version, the
pedestal body 154 comprises a metal material, such as at least one
of stainless steel, aluminum and titanium. For example, a suitable
heat exchange pedestal 151 may comprise a pedestal body 154
comprising stainless steel, and a suitable cooling pedestal 152 can
comprise a pedestal body 154 comprising aluminum.
[0061] A heating pedestal 151 further comprises a heater 155, such
as a resistive heater, or conduits (not shown) through which a
heated fluid can be flowed. The heating pedestal can also be heated
by overhead heating lamps (not shown.) The heating pedestal may be
capable of heating the substrate 104 to a temperature of at least
about 200.degree. C. to at least about 400.degree. C. The cooling
pedestal 152 can typically comprise cooling conduits 158 through
which a cooled fluid can be flowed to cool the substrate 104. The
cooling pedestal may be capable of cooling the substrate 104 to a
temperature of less than about 80.degree. C. One or more of the
heating and cooling pedestals 151, 152 may be located in a separate
chamber in an integrated vacuum multi-chamber system, an example of
which is shown in FIG. 6, to provide the desired heat treatment or
cooling of the substrate before or after processing of the
substrate 104 in a process chamber 106.
[0062] In one version, the heat exchange pedestal 150 comprises the
coating 24 comprising at least one of the contamination reducing
coatings. For example, the heat exchange pedestal 150 can comprise
a coating 24 comprising at least one of a diamond-like material and
a high-purity ceramic material. The coating 24 can be formed over
an upper surface 26 of the pedestal body 154 to protect the
substrate 104, and can even cover substantially the entire upper
surface 26 of the pedestal body 154. Also, the coating 24 can be
provided as a part of a protective cap 133 that covers the surface
26, as shown in FIG. 5. A thickness of the coating 24 is selected
to inhibit migration of the heating body materials to the substrate
104, while also providing good heating of the substrate 104. For
example, a suitable thickness of the coating 24 may be from about
0.25 micrometers to about 6 micrometers. The adhesion layer 140 may
be provided on the surface 26 of the heat exchange pedestal 150 to
secure the coating 24 to the pedestal 150. A suitable thickness of
the adhesion layer 140, such as a layer comprising titanium, may be
from about 0.25 micrometers to about 1 micrometer. In one version,
the heat exchange pedestal 150 comprises a coating 24 of a
diamond-like material. In another version, the heat exchange
pedestal comprises a coating 24 of high-purity silicon carbide. In
another version, the heat exchange pedestal comprises a coating 24
of high-purity silicon nitride. In yet another version, the heat
exchange pedestal 150 comprises a cap 133 having a base layer 130
comprising graphite or silicon infiltrated silicon carbide, and a
coating 24 of silicon carbide that substantially entirely covers
the base layer 130.
[0063] Furthermore, as the heat exchange pedestal 150 typically
exchanges heat with the substrate 104 substantially without
electrostatically holding the substrate 104, the support surface 22
may be tailored to improve retention of the substrate 104 on the
surface 22. For example, the surface 22 of the coating 24 on the
heat exchange pedestal 150 may comprise a slightly higher average
surface roughness than the surface of mesas 112 on an electrostatic
chuck. However, the surface roughness is desirably maintained low
enough to inhibit contamination of the substrate 104. A suitable
average surface roughness may be less than about 0.4 micrometers,
such as from about 0.1 micrometers to about 0.4 micrometers.
[0064] In one version, the retention of the substrate 104 is
improved by forming grooves 159 in the surface 22. The grooves 159
may comprise, for example radially spaced circular grooves. In one
version, the surface 22 comprises 4 grooves spaced at least about 1
cm apart, and having a depth of from about 50 micrometers to about
500 micrometers, and a width of from about 1 millimeter to about 3
millimeters. In one version, the grooves 159 are formed by
machining or otherwise forming grooves in surface 26 of the
pedestal body 154. A conformal coating 24 of the contamination
reducing coating is applied to the surface 26 of the pedestal body
154, resulting in a coating 24 having a grooved upper surface. An
adhesion layer 140 may also be applied before the conformal coating
24 is formed. Providing grooves 159 may be especially advantageous
for materials such as the diamond-like materials, which are
typically very smooth, and which in some instances may otherwise
not provide adequate retention of the substrates 104 on the
pedestal 150. In one version, the grooves 159 may even be adapted
to flow a heat exchange fluid therethrough to exchange heat with a
substrate 104 on the pedestal 150.
[0065] In one version, the surface 22 of the pedestal body 154
comprises a pattern of grooves 159 that is capable of equalizing
the pressure on the front and backside of a substrate 104 placed on
the surface 22. For example, the heat exchange pedestal 150 may
comprise a de-gassing pedestal that is used to de-gas substrates
104 before or after processing. The pattern of grooves 159 may
inhibit the build-up of a pressure differential between the
substrate front and backsides, thus reducing the incidence of
"sticking" of the substrate to the surface 22. An example of a
pattern of grooves 159 that is suitable for equalizing the pressure
is shown in FIG. 8. In this version, the pattern of grooves 159
comprises a plurality of circle grooves 173 having different radii,
and which are desirably concentric. The circle grooves 173 serve to
distribute gas pressure evenly about the center 174 of the surface
22. The circle grooves 173 can comprise, for example, a first
circle groove 17a having a first radius, and a second circle groove
173b having a second radius, the second radius being larger than
the first radius. The pattern of grooves 159 further comprises a
plurality of radius grooves 175 that extend across the substrate
receiving surface 22, and lie substantially only between the circle
grooves 173. The radial grooves serve to distribute the gas
pressure across the diameter of the surface 22. In one version, the
radius grooves extend substantially only from the first circle
groove 173a to the second circle groove 173b. The surface may
further comprise a recessed central region 176 that is within the
first circle groove 173a. The central region 176 inhibits contact
of the surface 22 with the substrate 104, to inhibit the adhesion
or sticking of substrates 104, such as slightly bowed substrates
104 to the center of the surface 22.
[0066] In one exemplary version, the pattern of grooves 159
comprises from about 3 to about 8 circle grooves 173, such as 4
circle grooves 173, and comprises from about 2 to about 24 radius
grooves 175, such as 12 radius grooves 175. The grooves 159 may
comprise a depth of from about 0.5 mm (0.02 inches) to about 1 mm
(0.04 inches), such as about 0.8 mm (0.03 inches). The grooves may
also comprise a rounded cross-sectional profile, such as a
half-circle cross-sectional profile, as shown for example in FIG.
2A. The pattern of grooves 159 may serve the further purpose of
reducing slipping of the substrate 104 on the surface 22 during
placement of the substrate 104 on the pedestal 150.
[0067] In yet another version, a component 20 comprising the
contamination-reducing material comprises a support structure 25
having a body 154 comprising a disc 177 with a recessed peripheral
ledge 178, as shown for example in FIGS. 8, 9a and 9b. For example,
the component 20 may comprise a heat exchange pedestal 150 such as
a de-gassing pedestal having a diamond-like coating 24 and recessed
peripheral ledge 178. The recessed peripheral ledge 178 comprises a
radial width that is sized sufficiently large such that the
perimeter edge 179 of the substrate 104 overhangs at least a
portion of the peripheral ledge 178, and contact between the ledge
178 and substrate 104 is substantially avoided, as shown for
example in FIG. 9b. The recessed peripheral ledge 178 can form a
continuous ring about the periphery of the disc 177, as shown in
FIG. 9a. The recessed peripheral ledge 178 is believed to reduce
the contamination of substrates 104 because contact is reduced
between the surface 22 of the pedestal 150 and the perimeter edge
179 of the substrate 104, which can comprise a contaminated region
in some substrates 104. Contact between a contaminated substrate
peripheral edge 179 and the surface 22 of the pedestal 150 can
result in the transfer of contaminant particulates to the pedestal
150, and the contamination of subsequent substrates 103 placed on
the pedestal 150. However, by providing a recessed peripheral ledge
178, the contact between such contaminated areas and the support
surface 22 is reduced, and the contamination of subsequent
substrates 104 placed on the surface 22 is also reduced. The
recessed peripheral ledge 178 may desirably comprise a radial width
of at least about {fraction (1/150)}.sup.th of the diameter of the
overall disc 177. For example, the recessed peripheral ledge 178
may comprise a radial width of at least about 2 mm for a disc 177
having a diameter of 300 mm. A suitable depth at which the
peripheral ledge 178 may be recessed away from a 25 top surface 182
of the disc 177 may be a depth of at least about 2 mm. The recessed
peripheral ledge 178 can be provided in combination with a pattern
of grooves 159 on the surface 22, as shown in FIG. 8, to provide
reduced contamination and pressure equalizing in the processing of
substrates 104.
[0068] In yet another version, a component 20 comprising the
contamination-reducing material comprises a support structure 25
comprising a lift pin 160, an embodiment of which is shown in FIG.
3. The lift pin 160 comprises a moveable elongated member 161
having a tip 162 adapted to lift and lower a substrate from a
surface of a support 100. The lift pin 160 can be a part of a lift
pin assembly 163, including a lift pin support 164 that holds one
or more lift pins 160, and that can be attached to a bellows (not
shown) to raise and lower the lift pins 160. The lift pin 160 can
comprise at least one of the contamination-reducing materials
described above, such as at least one of the diamond-like materials
and the high-purity ceramics. For example, the lift pin 160 may
comprise a coating 24 of the contamination reducing-material that
covers at least a portion of the tip 162 of the lift pin 160, to
provide a contact surface 22 that reduces contamination of the
substrate 104. In one version, a preferred contamination reducing
coating for the lift pin 160 comprises a coating 24 comprising a
diamond-like material, the coating 24 having a thickness or from
about 1 micrometer to about 4 micrometers on the tip 162 of the
lift pin 160. In another version, a preferred contamination
reducing coating for the lift pin 160 comprises a coating 24
comprising a high-purity ceramic comprising silicon nitride. In yet
another version, the preferred contamination reducing coating
comprises silicon carbide.
[0069] In yet another version, a component 20 that is capable of
reducing the contamination of substrates 104 comprises a substrate
lifting assembly 185 that is adapted to lift a substrate 104 from a
substrate support 100 and transport the substrate 104, as shown for
example in FIG. 10a. For example, the substrate lifting assembly
185 may be adapted to lift and lower a substrate 104 onto and off
of a support 100 such as a heat exchange pedestal 150. The lifting
assembly 185 comprises a hoop 186 that is sized to fit about a
periphery 187 of the support 100. A pair of arcuate fins 188 are
mounted on the hoop 186, for example in the opposing arrangement
shown in FIG. 10a. Each arcuate fin 188 comprises a pair of
opposing ends 189 that are angled inwardly towards the support 100.
Each opposing end 189 comprises a ledge 190 that also extends
inwardly towards the support 100.
[0070] The ledges 190 on each opposing end 189 of the arcuate fins
188 cooperate to form a lifting structure that is capable of
lifting a substrate 104 off of and onto the support 100 by setting
the substrate 104 on the ledges 190. The ledges 190 may be
connected to the opposing ends 189 by a beveled connecting region
191 that slopes downwardly from each end 189 to the ledge. The
ledges 190 are desirably sized to suitably support the substrate
104, and may also extend inwardly a sufficient distance to support
the substrate 104 without excessive contact or rubbing between the
beveled connecting region 191 and the substrate 104, thereby
reducing the contamination of the substrate 104. The ledges 190 may
even be sufficiently large such that the substrate 104
substantially does not contact the beveled connecting region 191 at
the opposing ends. For example, to lift and transport a substrate
104 having a diameter of about 300 mm, the ledges 190 may extend
inwardly from the opposing ends 189 by at least about 7 mm.
[0071] The substrate lifting assembly 185 is further improved by
providing at least one raised protrusion 192 on the upper surface
193 of each ledge 190 that is sized and shaped to minimize contact
between the substrate 104 and the ledge 190 during lifting and
lowering of the substrate 104, as shown for example in FIG. 10b.
Minimizing contact between the substrate 104 and ledge surface 193
further reduces the contamination of the substrate 104 by the ledge
190, allowing for improved results in the processing of the
substrate 104. Also, substrates 104 that have already been
contaminated can be safely handled by the lifting assembly 185
having the raised protrusions 192 substantially without
transferring excessive amounts of contamination to the ledges 190
or to subsequent substrates lifted by the ledges 190. The
protrusions 192 may also be located towards and even at inward ends
195 of the ledges 190, such that the raised protrusions 193 contact
the substrate 104 at regions away from the perimeter edge 179 of
the substrate 104, and which are typically less contaminated than
the perimeter edge 179 of the substrate 104. For example, the
raised protrusions 193 may be spaced away from the opposing ends
189 such that they contact the substrate at a diameter that is at
least about 4 mm inside the perimeter edge 179 of the substrate
104, and even at least about 7 mm inside the perimeter edge 179.
Thus, the protrusions 193 may be spaced away from the opposing ends
189 by at least about 4 mm and even at least about 7 mm. A suitable
height of the raised protrusions 193 to minimize contact of the
substrate 104 with the ledges 190 may be a height of at least about
1 mm, such as from about 1 mm to about 2 mm, and even at least
about 1.5 mm.
[0072] In one exemplary version, the substrate lifting assembly 185
comprises a single raised protrusion 193 on each ledge 190 of the
arcuate fins 188, yielding 4 total protrusions 193 on which a
substrate 104 to be lifted and transported may rest. Each
protrusion 193 is spaced inwardly from an opposing end 189 of the
arcuate fin 188 such that the protrusion 193 contacts the substrate
104 at a region that is about 7.5 mm inward of the perimeter edge
179 of the substrate 104. The protrusions have a height above the
surface 193 of the ledge 190 of about 1.6 mm ({fraction (1/16)}
inch.) In one version, the arcuate fins 188 comprise a metal
material, such as for example at least one of stainless steel and
aluminum. The arcuate fins 188 may also comprise a contamination
reducing material, such as a coating 24 of a diamond-like material
such as a diamond-like nanocomposite, to further reduce
contamination of the substrates 104. For example, the protrusions
193 may comprise a contamination-reducing material such as a
diamond-like nanocomposite. A contamination reducing-ceramic, such
as for example at least one of high purity alumina and quartz, or
other non-metallic material may also be provided to form the
protrusions 193, and the arcuate fins 188 may also be entirely made
of the contamination-reducing ceramic material. As shown in FIG.
10, a second pair of arcuate fins 188 may also be mounted above or
below the first pair of arcuate fins to allow the simultaneous
transport of more than one substrate 104.
[0073] In yet another version, the substrate lifting assembly may
be a part of a substrate transport system 198 further comprising a
substrate transfer arm 103 that is capable of transferring a
substrate to and from the pair of arcuate fins 188, as shown for
example in FIG. 7B. The substrate transfer arm 103 may be a part of
a transfer chamber robot 119 that is capable of delivering
substrates to different chambers in a multi-chamber apparatus, as
shown for example in FIG. 6. The substrate transport system may
further comprise a controller 194 having program code to control
the substrate transfer arm 103 and lifting assembly 185 to reduce
the contamination of substrates 104 being transported by the arm
103 and lifting assembly 185. In one version, the controller 194
comprises substrate centering control program code to send control
signals to the transfer arm 103 to move the transfer arm 103 such
that the substrate 104 is substantially aligned along a central
axis 197 of the chamber, and above the center of the support 100.
By correctly positioning the substrate 104 substantially aligned
with the central axis of the chamber 106, the correct positioning
of the substrate 104 on the arcuate fins 188 may be more readily
achieved, substantially without excessive slipping of the substrate
104 when placed on the arcuate fins 188, which slipping can
otherwise abrade and contaminate the substrate 104. The controller
194 may further comprise program code to raise the hoop 186 to lift
the arcuate fins 188 towards the substrate transfer arm 103, and to
operate the hoop 186 and transfer arm 103 in conjunction to
transfer the substrate between the transfer arm 103 and arcuate
fins 188. The hoop 186 may then be lowered by the controller 194 to
set the substrate 104 on the support 100 for processing.
[0074] In one version, the substrate transport system 198 comprises
a detector 199 that is capable of detecting a position of one or
more of the substrate 104 and transfer arm 103, and generating a
signal in relation to the detected position that can be used to
properly position the substrate 104 in the chamber 106. In one
version, the detector 199 comprises a pair of light sensors 200a,b
that are arranged on opposite ends 203a,b of a slit valve 201
comprising an opening through which the substrate 104 and transfer
arm 103 enter the chamber 106, as shown for example in FIG. 11. The
light sensors 200a,b may be capable of determining whether the
substrate 104 being transported through the slit valve 201 by the
transfer arm 103 is substantially centered as it passes through the
slit valve 210, or whether the substrate and transfer arm are
off-center and have been shifted towards one or the other end
203a,b of the slit valve. In one version, the light sensors 200a,b
are capable of detecting an intensity of light reaching each
sensor, and the intensity of light detected by each sensor 200a,b
can be compared to determine the relative position of the substrate
104 and transfer arm 103. For example, the amount of light that is
being blocked from reaching each light sensor 200a,b provides an
indication of the location of substrate 104 and transfer arm 103
relative to the sensors 200. The signal generated by the light
sensors 200a,b in relation to the detected light can thus be used
by the controller 194 to calculate the location of the substrate
104 as it is being transferred into the process chamber 106, and to
generate control signals to control the position of the transfer
arm 103 and substrate 104 in the chamber 106. Other means of
detecting the substrate position can also be used in addition to or
as an alternative to the light sensors 200a,b, and the light
sensors 200a,b can also comprise different arrangements about the
slit valve 201.
[0075] In one version, the controller 194 acts as a part of the
transport system 198 by using the signal generated by the detector
199 to calculate an offset distance that is a difference between
the detected position of the substrate 104 and a center of the
process chamber 106 that is aligned with the chamber central axis
197. The controller 104 can then generate a control signal in
relation to the offset distance to control the movement of the
transfer arm 103 to position the substrate 104 substantially over
the center of the support 100 and along the central axis 197 of the
chamber 106, thus reducing the incidence of abrasion of the
substrate 104 resulting from off-centered delivery of the substrate
104 to the lifting assembly 185. For example, the controller 194
may provide control instructions to the transfer arm 103 to move to
the left or right, for example towards one or other end 203a,b of
the slit valve 201, to center the substrate 104 in a plane parallel
to the central axis 197 of the chamber. The controller 194 may also
comprise program code to generate control instructions to move the
transfer arm 103 and substrate 104 forward into the chamber a
distance that is sufficient to align the center of the substrate
with the central axis 197 of the chamber 106, and position the
substrate 104 over substantially the center of the support 100.
Thus, the transport system 198 can be used to transport the
substrate into the process chamber and align the substrate 104 in
the chamber such that contamination due to misalignment and
abrasion of the substrate is reduced.
[0076] To remove the substrate 104 from the chamber 106, the
controller 194 may comprise program code to operate the transfer
arm 103 and lifting assembly 185 through the above transfer steps
in reverse. For example, the controller 194 may comprise program
code to operate the hoop 186 to lift the substrate 104 off the
support 100 and onto the arcuate fins 188, and raise the substrate
104 in the chamber 106 along the central axis 197. The transfer arm
103 may be operated to locate and move to the central axis 197 of
the chamber 106, and operate in conjunction with the lifting
assembly 185 to transfer the substrate 104 from the arcuate fins
188 to the transfer arm. The controller 194 may also use signals
from the detector 199 to align the transfer arm 103 in the process
chamber 106 to receive the substrate 104 from the lifting assembly
185 substantially without abrading and contamination the substrate
104. The controller 194 may then instruct the transfer arm 103 to
remove the substrate 104 from the chamber 106, and for example, to
provide a fresh substrate 104 in the chamber 106. Thus, the
transfer arm 103 and controller 194 can facilitate a reduction in
the contamination levels of processed substrates by providing for
the desired alignment of the substrate 104 in the chamber, such
that excessive abrasion and rubbing does not occur between the
substrate 104 and chamber components such as the lifting assembly
185 and support 100.
[0077] In one version, the transfer arm 103 that is capable of
transferring the substrate 104 into and out of the process chamber
106, for example from a vacuum or de-gassing chamber, may itself
comprise a contact surface 22 that contacts the substrate 104
during the transfer process, and that comprises a
contamination-reducing material that is capable of reducing
contamination of the substrate 104. For example, the transfer arm
103 may comprise a transfer blade 205 having a coating 24 of a
contamination-reducing material having the contact surface 22
thereon, as shown for example in FIG. 11. The
contamination-reducing material may be, for example, a diamond-like
material such as a diamond-like nanocomposite. In another example,
the transfer arm 103 may reduce contamination of the substrate 104
by minimizing contact with the substrate 104 as it is transferred
into and out of the process chamber 106. For example, the transfer
arm 103 may comprise one or more raised protrusions 206 that raise
the substrate 104 and minimize contact of the substrate 104 with
the rest of the transfer blade 205, such as raised protrusions
having a height of at least about 1.6 mm. In one version, the
protrusions 206 may even be arranged on the contact surface 22 of
the transfer blade 205 such that they substantially do not contact
the backside perimeter edge 179 of the substrate 104, thereby
reducing the contact between the transfer arm 103 and a region of
the substrate 104 that typically comprises a relatively high amount
of contaminants. For example, the raised protrusions may be
arranged such that they contact the backside of the substrate 104
at a diameter that is at least about 4 mm inside the perimeter edge
179 of the substrate 104. Thus, the transfer arm 103 may be adapted
to reduce the contamination of the substrate 104 during transfer of
the substrate into and out of a process chamber 106.
[0078] In another version, a component 20 comprising the
contamination-reducing material comprises a support shutter 180, an
embodiment of which is shown in FIG. 4. The support shutter 180 is
adapted to protect a surface 28 of a substrate support 100 when the
substrate 104 is not present on the support 100, for example during
a chamber cleaning process. The shutter 180 inhibits the deposition
of material onto the surface 28, such as material that can be
knocked loose from a sputtering target during cleaning of the
target and chamber. The shutter 180 typically comprises a structure
25 comprising a disc 181 that is sized and shaped to cover at least
a portion of the surface 28 of the support 100, and may even
substantially entirely cover an exposed surface 28 of the support
100. The surface 28 can comprise, for example, the top surfaces 22
of mesas 112 (not shown), and can also comprise the top of a
substantially planar support surface 28 (as shown.) A mechanical
arm (not shown) can rotate the shutter disc 181 onto the surface 28
of the support to cover the surface 28, and can rotate the shutter
disc 181 away from the support surface 28 to process a substrate
104 on the support 100.
[0079] To reduce contamination of the support surface 28, and thus
the substrate 104, the shutter disc 181 desirably comprises at
least one of the contamination-reducing materials described above,
such as for example at least one of the diamond-like materials and
high-purity ceramic materials. In one version, the shutter disc 181
comprises a bottom surface 183 comprising a coating 24 having the
contamination-reducing material. The coating 24 provides a lower
surface 184 that reduces contamination of the substrate and support
from metal particulates resulting from contact of the surface 184
with the surface 28 of the support 100. The shutter disc 181 can
also be mechanically attached to a coating layer 24 of
contamination reducing coating, for example with a connecting pin.
In another version, the disc 181 comprises a top surface 189 having
the metal-contamination reducing material, such as the coating 24
(not shown), and the disc 181 may also comprise a coating 24 that
covers substantially the entire disc. The shutter disc 181 can
comprise a contamination reducing material comprising, for example,
at least one of high purity silicon carbide, silicon nitride,
silicon and silicon oxide. In a preferred version, the lower
surface 184 of the shutter disc 181 comprises a contamination
reducing coating 24 comprising a high-purity silicon nitride
material.
[0080] Other components 20 that could comprise the
contamination-reducing materials described can include the blades
of robot transfer arms, rings on a substrate support, and other
components involved in the support or transfer of substrates 104
for processing.
[0081] The components 20 having the contamination reducing coatings
may be a part of a multi-chamber apparatus 102 comprising a
plurality of processing chambers 106a-d. An embodiment of an
apparatus 102 suitable for processing substrates 10 comprises one
or more processing chambers 106a-d, as shown in FIG. 6. The
chambers 106a-d are mounted on a platform, such as an Endura 2
platform from Applied Materials, Inc., of Santa Clara, Calif., that
provides electrical, plumbing, and other support functions. The
platform 109 typically supports a load lock 113 to receive a
cassette 115 of substrates 104 to be processed and a substrate
transfer chamber 117 containing a robot 119 to transfer substrates
from the cassette 115 to the different chambers 106a-d for
processing and return them after processing. The different chambers
106a-d may include, for example, a cleaning chamber, an etching
chamber, a deposition chamber for depositing materials on
substrates, optionally, a heat treatment chamber, and other
processing chambers. For example, in one version, one of the
chambers 106a-d comprises a heat treatment chamber comprising a
heating pedestal 151 to heat the substrate 104 before processing to
degas the substrate 104. After degassing of the substrate 104, the
substrate 104 can be transferred by the robot 119 to a process
chamber 106 to etch material on the substrate 104. The substrate
104 can also be transferred by the robot 119 to a process chamber
comprising a deposition chamber, for example to deposit a barrier
layer onto a substrate 104 held on an electrostatic chuck. After
processing, the substrate 104 can be transferred by the robot 119
to a cool-down chamber where the substrate can be placed on a
cooling pedestal 152 to cool the substrate 104. The chambers 106a-d
are interconnected to form a continuous vacuum environment within
the apparatus 102 in which the process may proceed uninterrupted,
thereby reducing contamination of substrates 104 that may otherwise
occur when transferring wafers between separate chambers for
different process stages. The components in the apparatus 102, such
as components that contact or support the substrate 104, also
desirably comprise contamination reducing materials to reduce the
contamination of the substrate 104.
[0082] In one version, the apparatus 102 comprises a transfer
chamber 117 comprising a robot 119 having the transfer arm 103; a
degas or heating chamber 106a having a heating pedestal 151; a
pre-clean chamber 106b adapted to clean a substrate 104 before a
deposition process by exposing the substrate 104 to an energized
pre-clean gas, the pre-clean chamber comprising a substrate support
100; a deposition chamber 106c, such as a physical vapor deposition
or chemical vapor deposition chamber adapted to deposit a material
on the substrate 104, the deposition chamber 106c having a
substrate support 100; and a cool-down chamber 106d to cool the
substrate 104 after processing, the cool-down chamber comprising a
cooling pedestal 152. One or more of the chambers 106a-d may
further comprise the substrate lifting assembly 185 with the
arcuate fins 188 to raise and lower the substrate 104 on and off of
the pedestals 151, 152 and supports 100. The components of the
multi-chamber apparatus 102, including the transfer arm 103,
lifting assembly 185, supports 100 and pedestals 151, 152 desirably
comprise contamination-reducing materials and/or
contamination-reducing structures such that a substrate cycled
through each of the chambers has a contamination level of less than
about 5.times.10.sup.10 atoms/cm.sup.3 for iron, and less than
about 1.times.10.sup.11 atoms/cm.sup.3 for all other metal
ions.
[0083] An embodiment of a process chamber 106 which may comprise
the components 20 having the contamination-reducing material is
shown in FIG. 7b. The chamber 106 comprises an enclosure wall 118,
which may comprise a ceiling, sidewalls, and a bottom wall that
enclose a process zone 113. In operation, process gas is introduced
into the chamber 106 through a gas supply 130 that includes a
process gas source, and a gas distributor. The gas distributor may
comprise one or more conduits having one or more gas flow valves
and one or more gas outlets around a periphery of the substrate 104
which may be held in the process zone 111 on the substrate support
100 having a substrate receiving surface 180. Alternatively, the
gas distributor may comprise a showerhead gas distributor (not
shown). Spent process gas and process byproducts are exhausted from
the chamber 106 through an exhaust 120 which may include an exhaust
conduit that receives spent process gas from the process zone 113,
a throttle valve to control the pressure of process gas in the
chamber 106, and one or more exhaust pumps.
[0084] The process gas may be energized to process the substrate
104 by a gas energizer 116 that couples energy to the process gas
in the process zone 1 13 of the chamber 106. In one version, the
gas energizer 116 comprises process electrodes that may be powered
by a power supply to energize the process gas. The process
electrodes may include an electrode that is or is in a wall, such
as a sidewall or ceiling of the chamber 106 that may be
capacitively coupled to another electrode, such as an electrode 108
in the support 100 below the substrate 104. Alternatively or
additionally, the gas energizer 116 may comprise an antenna
comprising one or more inductor coils which may have a circular
symmetry about the center of the chamber. In yet another version,
the gas energizer 116 may comprise a microwave source and waveguide
to activate the process gas by microwave energy in a remote zone
upstream from the chamber 106. In a physical vapor deposition
chamber 106 adapted to deposit material on a substrate 104, the
chamber further comprises a target 114 facing the substrate 104
that is sputtered by the energized gas to deposit material from the
target 114 onto the substrate 104.
[0085] To process a substrate 104, the process chamber 106 is
evacuated and maintained at a predetermined sub-atmospheric
pressure. The substrate 104 is then provided on the support 100 by
a substrate transport, such as for example a robot arm 103 and a
lift pin 160. The substrate 104 can be held on the support 100 by
applying a voltage to the electrode 108 in the support 100, for
example via an electrode power supply 172. The gas supply 130
provides a process gas to the chamber 106 and the gas energizer 116
couples RF or microwave energy to the process gas to energizes the
gas to process the substrate 104. Effluent generated during the
chamber process is exhausted from the chamber 106 by the exhaust
120.
[0086] The chamber 106 and multi-chamber apparatus 101 can be
controlled by a controller 194 that comprises program code having
instruction sets to operate components of each chamber 106a-d to
process substrates 104 in the chamber 106, as shown for example in
FIG. 7b. For example, the controller 194 can comprise a substrate
positioning instruction set to operate one or more of the substrate
support 100 and robot arm 119 and lift pins 160 to position a
substrate 104 in the chamber 106; a gas flow control instruction
set to operate the gas supply 130 and flow control valves to set a
flow of gas to the chamber 106; a gas pressure control instruction
set to operate the exhaust 120 and throttle valve to maintain a
pressure in the chamber 106; a gas energizer control instruction
set to operate the gas energizer 116 to set a gas energizing power
level; a temperature control instruction set to control
temperatures in the chamber 106; and a process monitoring
instruction set to monitor the process in the chamber 106.
[0087] Embodiments of the invention provide substantial benefits in
the processing of substrates, and in particular in the reduction of
contamination of substrates 104 by metal ions such as iron.
Providing the contamination-reducing materials, as well as
contamination reducing components such as the transport blade, can
reduce contamination levels to on the order of less than
5.times.10.sup.10 atoms/cm.sup.3 for iron, and 1.times.10.sup.11
atoms/cm.sup.3 for all other ions, by substantially eliminating
contact of the substrate 104 with metal components or components
having a metallic surface.
[0088] Although exemplary embodiments of the present invention are
shown and described, those of ordinary skill in the art may devise
other embodiments which incorporate the present invention, and
which are also within the scope of the present invention. For
example, the support 100, heat exchange pedestal 150, lift pins
160, or other components 20 may comprise other shapes and
configurations other than those specifically described. Also, the
contamination-reducing materials may be fabricated by means other
than those specifically described and may comprise different
configurations on the components 20. Furthermore, relative or
positional terms shown with respect to the exemplary embodiments
are interchangeable. Therefore, the appended claims should not be
limited to the descriptions of the preferred versions, materials,
or spatial arrangements described herein to illustrate the
invention.
* * * * *