U.S. patent application number 11/611061 was filed with the patent office on 2008-06-19 for rapid conductive cooling using a secondary process plane.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Alexander N. Lerner, Khurshed Sorabji.
Application Number | 20080142497 11/611061 |
Document ID | / |
Family ID | 39312914 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080142497 |
Kind Code |
A1 |
Sorabji; Khurshed ; et
al. |
June 19, 2008 |
RAPID CONDUCTIVE COOLING USING A SECONDARY PROCESS PLANE
Abstract
A method and apparatus for thermally processing a substrate is
described. The apparatus includes a substrate support configured to
move linearly and/or rotationally by a magnetic drive. The
substrate support is also configured to receive a radiant heat
source to provide heating region in a portion of the chamber. An
active cooling region comprising a cooling plate is disposed
opposite the heating region. The substrate may move between the two
regions to facilitate rapidly controlled heating and cooling of the
substrate.
Inventors: |
Sorabji; Khurshed; (San
Jose, CA) ; Lerner; Alexander N.; (San Jose,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
APPLIED MATERIALS, INC.
|
Family ID: |
39312914 |
Appl. No.: |
11/611061 |
Filed: |
December 14, 2006 |
Current U.S.
Class: |
219/393 ;
165/80.4; 219/399; 219/411 |
Current CPC
Class: |
H01L 21/30 20130101;
H01L 21/67115 20130101; H01L 2924/0002 20130101; C30B 31/14
20130101; H01L 21/67098 20130101; H01L 21/67109 20130101; H01L
2924/0002 20130101; H01L 22/10 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
219/393 ;
219/399; 219/411; 165/80.4 |
International
Class: |
H01L 21/67 20060101
H01L021/67; F27D 11/00 20060101 F27D011/00; H01L 21/477 20060101
H01L021/477; F28F 7/00 20060101 F28F007/00 |
Claims
1. A substrate processing apparatus, comprising: a chamber; a
magnetically driven substrate support disposed in the chamber and
comprising an annular body configured to support the substrate on
an upper surface thereof; an annular extension coupled to the
annular body; and a window coupled to the annular body, wherein the
window is disposed below the substrate and is transparent to light
and heat.
2. The apparatus of claim 1, further comprising: a heat source
disposed in the chamber.
3. The apparatus of claim 2, wherein the heat source is disposed
below the window.
4. The apparatus of claim 1, further comprising: an annular ring
detachably coupled to the annular extension.
5. The apparatus of claim 1, wherein the annular body is configured
to magnetically couple to a stator assembly.
6. The apparatus of claim 1, further comprising: a plurality of
lift pins extending from an upper surface of the window.
7. A substrate processing apparatus, comprising: a chamber having
an interior volume which includes an upper portion and a lower
portion; a cooling source and a heat source disposed in the
interior volume, the cooling source opposing the heat source; and a
levitating substrate support configured to move the substrate
between the upper portion and the lower portion.
8. The apparatus of claim 7, wherein the cooling source is disposed
in an upper portion of the interior volume and the heat source is
disposed in a lower portion of the interior volume.
9. The apparatus of claim 7, wherein the cooling source comprises a
black material.
10. The apparatus of claim 7, wherein the cooling source comprises
at least one fluid channel for flowing a coolant therein.
11. The apparatus of claim 7, wherein the substrate support has an
inside diameter sized to receive the heat source.
12. The apparatus of claim 7, wherein the substrate support has a
support ring configured to receive and support the substrate.
13. The apparatus of claim 7, further comprising: a window disposed
between the heat source and the substrate, wherein the window is
transparent to ultra-violet light.
14-28. (canceled)
29. A substrate processing apparatus, comprising: a chamber having
an interior volume which includes an upper portion and a lower
portion; a cooling source in communication with the upper portion
and a heat source disposed in the lower portion of the interior
volume; a levitating substrate support configured to move the
substrate between the upper portion and the lower portion; and a
window disposed between the heat source and the substrate, wherein
the window is transparent to ultra-violet light.
30. The apparatus of claim 29, wherein the cooling source comprises
a cooling plate.
31. The apparatus of claim 30, wherein the cooling plate comprises
a black material.
32. The apparatus of claim 30, wherein the cooling plate has an
emissivity between about 0.70 to about 0.95.
33. The apparatus of claim 29, wherein the cooling source is a gas
port coupled to a coolant source.
34. The apparatus of claim 29, wherein the cooling source comprises
at least one fluid channel for flowing a coolant therein.
35. The apparatus of claim 29, wherein the cooling source comprises
a cooling plate having at least one channel for flowing a coolant
therein, and a gas port coupled to a coolant source.
36. The apparatus of claim 29, wherein the window includes a
plurality of lift pins extending from an upper surface thereof.
37. A substrate processing apparatus, comprising: a chamber having
an interior volume which includes an upper portion and a lower
portion; a heat source disposed in the lower portion; a cooling
source disposed in the upper portion; a magnetically driven
substrate support at least partially disposed in the interior
volume, the substrate support comprising an annular body configured
to support the substrate on an upper surface thereof; and a window
disposed between the heat source and the substrate, wherein the
window is transparent to ultra-violet light.
38. The apparatus of claim 37, wherein the window includes a
plurality of lift pins extending from an upper surface thereof.
39. The apparatus of claim 37, wherein the cooling source comprises
a cooling plate.
40. The apparatus of claim 39, wherein the cooling plate comprises
a black material.
41. The apparatus of claim 39, wherein the cooling plate has an
emissivity between about 0.70 to about 0.95.
42. The apparatus of claim 37, wherein the cooling source is a gas
port coupled to a coolant source.
43. The apparatus of claim 37, wherein the cooling source comprises
at least one fluid channel for flowing a coolant therein.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Embodiments of the present invention generally relate to a
method and apparatus for processing semiconductor substrates. More
specifically, to a method and apparatus for thermally treating
semiconductor substrates.
[0003] 2. Description of the Related Art
[0004] Integrated circuits have evolved into complex devices that
can include millions of transistors, capacitors, and resistors on a
single chip. The evolution of chip design continually requires
faster circuitry and greater circuit density that demand
increasingly precise fabrication processes. One fabrication process
frequently used is ion implantation.
[0005] Ion implantation is particularly important in forming
transistor structures on semiconductor substrates and may be
repeated many times during chip fabrication. During ion
implantation, a semiconductor substrate, typically comprising a
silicon material and/or a silicon containing film, is bombarded by
a beam of electrically charged ions, commonly called dopants. Ion
implantation changes the properties of the material in which the
dopants are implanted in order to achieve a particular level of
electrical performance. Dopant concentration may be determined by
controlling the number of ions in a beam of energy projected on the
substrate and the number of times the substrate passes through the
beam. The dopants are accelerated to an energy level that will
enable the dopants to penetrate the silicon material or implant
into the film at a desired depth. The energy level of the beam
typically determines the depth at which the dopants are placed.
[0006] During ion implantation, the implanted film may develop a
high level of internal stress. In order to relieve the stress and
further control the resulting properties of the implanted film, the
film is typically subjected to a thermal process, such as
annealing. Post-ion implantation annealing is typically performed
in a rapid thermal processing (RTP) chamber that subjects the
substrate to a very brief, yet highly controlled thermal cycle that
can heat the substrate from room temperature to approximately
450.degree. C. to about 1400.degree. C. RTP typically minimizes or
relieves the stress induced during implantation and can be used to
further modify film properties, such as changing the electrical
characteristics of the film by controlling dopant diffusion.
[0007] The RTP heating regime generally includes heating from a
radiant heat source, such as lamps and/or resistive heating
elements. In a conventional RTP system, the substrate is heated to
a desired temperature, and then the radiant heat source is turned
off, which causes the substrate to cool. In some systems, a gas may
be flowed onto the substrate to enhance cooling. However, as
processing parameters continue to evolve, temperature ramp up and
heating uniformity during RTP requires closer monitoring and
control. While conventional RTP chambers rely on the radiant heat
source to rapidly heat the substrate to a desired temperature, the
challenges arise when the substrate requires cooling to improve
heating uniformity, and/or when the substrate needs to be rapidly
cooled. For example, if a significant temperature gradient exists
across the substrate, the substrate may plastically deform or warp,
which may be detrimental to subsequent processes performed on the
substrate. Further, the faster cooling and/or enhanced temperature
control of the substrate may result in higher throughput and
enhanced dopant uniformity.
[0008] Therefore, what is needed is an apparatus and method for
rapid heating and cooling of a semiconductor substrate, with
enhanced control of heat uniformity.
SUMMARY OF THE INVENTION
[0009] The present invention generally describes a method and
apparatus for thermally processing a substrate. The apparatus
includes a chamber having an active heating means and an active
cooling means disposed therein. The chamber also includes a
substrate support movable between the heating means and the cooling
means. In one embodiment, the active cooling means is a cooling
plate having at least one fluid channel disposed therein. In
another embodiment, the active cooling means includes a coolant
source coupled to an inlet for supplying a cooling gas to an
interior volume of the chamber. In one embodiment, the heating
means is a plurality of heat lamps, which is disposed opposite the
cooling means.
[0010] In one embodiment, a substrate processing apparatus is
described. The apparatus includes a chamber, a magnetically driven
substrate support disposed in the chamber and comprising an annular
body configured to support the substrate on an upper surface
thereof, and a window coupled to the annular body, wherein the
window is disposed below the substrate and is transparent to light
and heat.
[0011] In another embodiment, a substrate processing apparatus is
described. The apparatus includes a chamber having an interior
volume which includes an upper portion and a lower portion, a
cooling plate and a heat source disposed in the interior volume,
the cooling plate opposing the heat source, and a levitating
substrate support configured to move the substrate between the
upper portion and the lower portion.
[0012] In another embodiment, a method for thermally treating a
substrate is described. The method includes providing a chamber
having a levitating substrate support disposed therein, moving the
substrate to a first position, heating the substrate in the first
position, moving the substrate to a second position adjacent an
active cooling means, and cooling the substrate in the second
position, wherein the first and second positions are disposed in
the chamber.
[0013] In another embodiment, a method for thermally treating a
substrate is described. The method includes providing a substrate
to a chamber at a first temperature, heating the substrate in a
first time period to a second temperature, heating the substrate to
third temperature in a second time period, cooling the substrate to
the second temperature in the second time period, and cooling the
substrate to the first temperature in a third time period, wherein
the second time period is less than about 2 seconds.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0015] FIG. 1 is a simplified isometric view of one embodiment of a
rapid thermal processing (RTP) chamber.
[0016] FIG. 2 is an isometric view of one embodiment of a substrate
support.
[0017] FIG. 3 is a schematic side view of another embodiment of an
RTP chamber.
[0018] FIG. 4 is a partial schematic side view of another
embodiment of an RTP chamber.
[0019] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0020] FIG. 1 is a simplified isometric view of one embodiment of a
rapid thermal processing chamber 100. Examples of rapid thermal
processing chambers that may be adapted to benefit from the
invention are Quantum X plus and CENTURA.RTM. thermal processing
systems, both available from Applied Materials, Inc., located in
Santa Clara, Calif. Although the apparatus is described as utilized
within a rapid thermal processing chamber, embodiments described
herein may be utilized in other processing systems and devices
where at least two temperature zones within one processing region
is desired, such as substrate support platforms adapted for robot
handoffs, orientation devices, deposition chambers, etch chambers,
electrochemical processing apparatuses and chemical mechanical
polishing devices, among others, particularly where the
minimization of particulate generation is desired.
[0021] The processing chamber 100 includes a contactless or
magnetically levitated substrate support 104, a chamber body 102,
having walls 108, a bottom 110, and a top 112 defining an interior
volume 120. The walls 108 typically include at least one substrate
access port 148 to facilitate entry and egress of a substrate 140
(a portion of which is shown in FIG. 1). The access port may be
coupled to a transfer chamber (not shown) or a load lock chamber
(not shown) and may be selectively sealed with a valve, such as a
slit valve (not shown). In one embodiment, the substrate support
104 is annular and the chamber 100 includes a radiant heat source
106 disposed in an inside diameter of the substrate support 104.
Examples of an RTP chamber that may be modified and a substrate
support that may be used is described in U.S. Pat. No. 6,800,833,
filed Mar. 29, 2002 and issued on Oct. 5, 2004, U.S. patent
application Ser. No. 10/788,979, filed Feb. 27, 2004 and published
as U.S. patent Publication No. 2005/0191044 on Sep. 1, 2005, both
of which are incorporated by reference in their entireties.
[0022] The substrate support 104 is adapted to magnetically
levitate and rotate within the interior volume 120. The substrate
support 104 is capable of rotating while raising and lowering
vertically during processing, and may also be raised or lowered
without rotation before, during, or after processing. This magnetic
levitation and/or magnetic rotation prevents or minimizes particle
generation due to the absence or reduction of moving parts
typically required to raise/lower and/or rotate the substrate
support.
[0023] The chamber 100 also includes a window 114 made from a
material transparent to heat and light of various wavelengths,
which may include light in the infra-red (IR) spectrum, through
which photons from the radiant heat source 106 may heat the
substrate 140. In one embodiment, the window 114 is made of a
quartz material, although other materials that are transparent to
light may be used, such as sapphire. The window 114 may also
include a plurality of lift pins 144 coupled to an upper surface of
the window 114, which are adapted to selectively contact and
support the substrate 140, to facilitate transfer of the substrate
into and out of the chamber 100. Each of the plurality of lift pins
144 are configured to minimize absorption of energy from the
radiant heat source 106 and may be made from the same material used
for the window 114, such as a quartz material. The plurality of
lift pins 144 may be positioned and radially spaced from each other
to facilitate passage of an end effector coupled to a transfer
robot (not shown). Alternatively, the end effector and/or robot may
be capable of horizontal and vertical movement to facilitate
transfer of the substrate 140.
[0024] In one embodiment, the radiant heat source 106 includes a
lamp assembly formed from a housing which includes a plurality of
honeycomb tubes 160 in a coolant assembly 360 (shown in FIG. 3)
coupled to a coolant source 183. The coolant source 183 may be one
or a combination of water, ethylene glycol, nitrogen (N.sub.2), and
helium (He). The housing may be made of a copper material or other
suitable material having suitable coolant channels formed therein
for flow of the coolant from the coolant source 183. Each tube 160
may contain a reflector and a high-intensity lamp assembly or an IR
emitter from which is formed a honeycomb-like pipe arrangement.
This close-packed hexagonal arrangement of pipes provides radiant
energy sources with high-power density and good spatial resolution.
In one embodiment, the radiant heat source 106 provides sufficient
radiant energy to thermally process the substrate, for example,
annealing a silicon layer disposed on the substrate 140. The
radiant heat source 106 may further comprise annular zones, wherein
the voltage supplied to the plurality of tubes 160 by the
controller 124 may varied to enhance the radial distribution of
energy from the tubes 160. Dynamic control of the heating of the
substrate 140 may be effected by the one or more temperature
sensors 117 (described in more detail below) adapted to measure the
temperature across the substrate 140.
[0025] A stator assembly 118 circumscribes the walls 108 of the
chamber body 102 and is coupled to one or more actuator assemblies
122 that control the elevation of the stator assembly 118 along the
exterior of the chamber body 102. In one embodiment (not shown),
the chamber 100 includes three actuator assemblies 122 disposed
radially about the chamber body, for example, at about 120.degree.
angles about the chamber body 102. The stator assembly 118 is
magnetically coupled to the substrate support 104 disposed within
the interior volume 120 of the chamber body 102. The substrate
support 104 may comprise or include a magnetic portion to function
as a rotor, thus creating a magnetic bearing assembly to lift
and/or rotate the substrate support 104. In one embodiment, at
least a portion of the substrate support 104 is partially
surrounded by a trough 412 (shown in FIG. 4) that is coupled to a
fluid source 186, which may include water, ethylene glycol,
nitrogen (N.sub.2), helium (He), or combinations thereof, adapted
as a heat exchange medium for the substrate support. The stator
assembly 118 may also include a housing 190 to enclose various
parts and components of the stator assembly 118. In one embodiment,
the stator assembly 118 includes a drive coil assembly 168 stacked
on a suspension coil assembly 170. The drive coil assembly 168 is
adapted to rotate and/or raise/lower the substrate support 104
while the suspension coil assembly 170 may be adapted to passively
center the substrate support 104 within the processing chamber 100.
Alternatively, the rotational and centering functions may be
performed by a stator having a single coil assembly.
[0026] An atmosphere control system 164 is also coupled to the
interior volume 120 of the chamber body 102. The atmosphere control
system 164 generally includes throttle valves and vacuum pumps for
controlling chamber pressure. The atmosphere control system 164 may
additionally include gas sources for providing process or other
gases to the interior volume 120. The atmosphere control system 164
may also be adapted to deliver process gases for thermal deposition
processes.
[0027] The chamber 100 also includes a controller 124, which
generally includes a central processing unit (CPU) 130, support
circuits 128 and memory 126. The CPU 130 may be one of any form of
computer processor that can be used in an industrial setting for
controlling various actions and sub-processors. The memory 126, or
computer-readable medium, may be one or more of readily available
memory such as random access memory (RAM), read only memory (ROM),
floppy disk, hard disk, or any other form of digital storage, local
or remote, and is typically coupled to the CPU 130. The support
circuits 128 are coupled to the CPU 130 for supporting the
controller 124 in a conventional manner. These circuits include
cache, power supplies, clock circuits, input/output circuitry,
subsystems, and the like.
[0028] In one embodiment, each of the actuator assemblies 122
generally comprise a precision lead screw 132 coupled between two
flanges 134 extending from the walls 108 of the chamber body 102.
The lead screw 132 has a nut 158 that axially travels along the
lead screw 132 as the screw rotates. A coupling 136 is coupled
between the stator 118 and nut 158 so that as the lead screw 132 is
rotated, the coupling 136 is moved along the lead screw 132 to
control the elevation of the stator 118 at the interface with the
coupling 136. Thus, as the lead screw 132 of one of the actuators
122 is rotated to produce relative displacement between the nuts
158 of the other actuators 122, the horizontal plane of the stator
118 changes relative to a central axis of the chamber body 102.
[0029] In one embodiment, a motor 138, such as a stepper or servo
motor, is coupled to the lead screw 132 to provide controllable
rotation in response to a signal by the controller 124.
Alternatively, other types of actuators 122 may be utilized to
control the linear position of the stator 118, such as pneumatic
cylinders, hydraulic cylinders, ball screws, solenoids, linear
actuators and cam followers, among others.
[0030] The chamber 100 also includes one or more sensors 116, which
are generally adapted to detect the elevation of the substrate
support 104 (or substrate 140) within the interior volume 120 of
the chamber body 102. The sensors 116 may be coupled to the chamber
body 102 and/or other portions of the processing chamber 100 and
are adapted to provide an output indicative of the distance between
the substrate support 104 and the top 112 and/or bottom 110 of the
chamber body 102, and may also detect misalignment of the substrate
support 104 and/or substrate 140.
[0031] The one or more sensors 116 are coupled to the controller
124 that receives the output metric from the sensors 116 and
provides a signal or signals to the one or more actuator assemblies
122 to raise or lower at least a portion of the substrate support
104. The controller 124 may utilize a positional metric obtained
from the sensors 116 to adjust the elevation of the stator 118 at
each actuator assembly 122 so that both the elevation and the
planarity of the substrate support 104 and substrate 140 seated
thereon may be adjusted relative to and a central axis of the RTP
chamber 100 and/or the radiant heat source 106. For example, the
controller 124 may provide signals to raise the substrate support
by action of one actuator 122 to correct axial misalignment of the
substrate support 104, or the controller may provide a signal to
all actuators 122 to facilitate simultaneous vertical movement of
the substrate support 104.
[0032] The one or more sensors 116 may be ultrasonic, laser,
inductive, capacitive, or other type of sensor capable of detecting
the proximity of the substrate support 104 within the chamber body
102. The sensors 116, may be coupled to the chamber body 102
proximate the top 112 or coupled to the walls 108, although other
locations within and around the chamber body 102 may be suitable,
such as coupled to the stator 118 outside of the chamber 100. In
one embodiment, one or more sensors 116 may be coupled to the
stator 118 and are adapted to sense the elevation and/or position
of the substrate support 104 (or substrate 140) through the walls
108. In this embodiment, the walls 108 may include a thinner
cross-section to facilitate positional sensing through the walls
108.
[0033] The chamber 100 also includes one or more temperature
sensors 117, which may be adapted to sense temperature of the
substrate 140 before, during, and after processing. In the
embodiment depicted in FIG. 1, the temperature sensors 117 are
disposed through the top 112, although other locations within and
around the chamber body 102 may be used. The temperature sensors
117 may be optical pyrometers, as an example, pyrometers having
fiber optic probes. The sensors 117 may be adapted to couple to the
top 112 in a configuration to sense the entire diameter of the
substrate, or a portion of the substrate. The sensors 117 may
comprise a pattern defining a sensing area substantially equal to
the diameter of the substrate, or a sensing area substantially
equal to the radius of the substrate. For example, a plurality of
sensors 117 may be coupled to the top 112 in a radial or linear
configuration to enable a sensing area across the radius or
diameter of the substrate. In one embodiment (not shown), a
plurality of sensors 117 may be disposed in a line extending
radially from about the center of the top 112 to a peripheral
portion of the top 112. In this manner, the radius of the substrate
may be monitored by the sensors 117, which will enable sensing of
the diameter of the substrate during rotation.
[0034] The RTP chamber 100 also includes a cooling block 180
adjacent to, coupled to, or formed in the top 112. Generally, the
cooling block 180 is spaced apart and opposing the radiant heat
source 106. The cooling block 180 comprises one or more coolant
channels 184 coupled to an inlet 181A and an outlet 181B. The
cooling block 180 may be made of a process resistant material, such
as stainless steel, aluminum, a polymer, or a ceramic material. The
coolant channels 184 may comprise a spiral pattern, a rectangular
pattern, a circular pattern, or combinations thereof and the
channels 184 may be formed integrally within the cooling block 180,
for example by casting the cooling block 180 and/or fabricating the
cooling block 180 from two or more pieces and joining the pieces.
Additionally or alternatively, the coolant channels 184 may be
drilled into the cooling block 180.
[0035] As described herein, the chamber 100 is adapted to receive a
substrate in a "face-up" orientation, wherein the deposit receiving
side or face of the substrate is oriented toward the cooling block
180 and the "backside" of the substrate is facing the radiant heat
source 106. The "face-up" orientation may allow the energy from the
radiant heat source 106 to be absorbed more rapidly by the
substrate 140 as the backside of the substrate is typically less
reflective than the face of the substrate.
[0036] Although the cooling block 180 and radiant heat source 106
is described as being positioned in an upper and lower portion of
the interior volume 120, respectively, the position of the cooling
block 180 and the radiant heat source 106 may be reversed. For
example, the cooling block 180 may be sized and configured to be
positioned within the inside diameter of the substrate support 104,
and the radiant heat source 106 may be coupled to the top 112. In
this arrangement, the quartz window 114 may be disposed between the
radiant heat source 106 and the substrate support 104, such as
adjacent the radiant heat source 106 in the upper portion of the
chamber 100. Although the substrate 140 may absorb heat more
readily when the backside is facing the radiant heat source 106,
the substrate 140 could be oriented in a face-up orientation or a
face down orientation in either configuration.
[0037] The inlet 181A and outlet 181B may be coupled to a coolant
source 182 by valves and suitable plumbing and the coolant source
182 is in communication with the controller 124 to facilitate
control of pressure and/or flow of a fluid disposed therein. The
fluid may be water, ethylene glycol, nitrogen (N.sub.2), helium
(He), or other fluid used as a heat exchange medium.
[0038] FIG. 2 is an isometric view of one embodiment of a substrate
support 104. The substrate support 104 includes an annular body 220
having an inside diameter 209 sized to receive the radiant heat
source and other hardware (not shown in this view). The substrate
support 104 is at least partially comprised of a magnetic ring
section 208 and a support section 212. The magnetic ring section
208 may be at least partially comprised of a magnetic material,
such as a ferrous containing material, to facilitate magnetic
coupling of the substrate support 104 to the stator 118. The
ferrous containing material includes low carbon steel, stainless
steel, which may include a plating, such as a nickel plating. In
one embodiment, the magnetic ring section 208 is comprised of a
plurality of permanent magnets disposed in a polar array about a
central axis. The magnetic ring section 208 may additionally
include an outer surface having one or more channels 223 formed
therein. In one embodiment, the magnetic ring section 208 includes
a shaped profile, such as an "E" shape or "C" shape having one or
more channels 223 formed therein.
[0039] The support section 212 is generally adapted to minimize
energy loss, such as heat and/or light, from the radiant heat
source 106, such that a substantial portion of energy from the
radiant heat source 106 is contained within the region between the
lower surface of the substrate 140 and the upper end of the radiant
heat source 106 (not shown in this Figure). The support section 212
may be an annular extension 214 extending from an upper surface of
the magnetic ring section 208. The support section 212 may also
include a support ring 210 that, in one embodiment, facilitates
alignment and provides a seating surface 202 for the substrate 140.
In one embodiment, at least a portion of the support ring 210 is
made from a material that is transparent to energy from the radiant
heat source 106, such as a quartz material. In another embodiment,
the support ring 210 comprises a silicon carbide material that may
be sintered. The support ring 210 may further include an oxide
coating or layer, which may comprise nitrogen. An example of a
support ring 210 that may be used is described in U.S. Pat. No.
6,888,104, filed Feb. 5, 2004, and issued on May 3, 2005, which is
incorporated by reference in its entirety.
[0040] The support ring 210 generally includes an inner wall 222
and a support lip 219 extending inwardly from the inner wall 222.
The inner wall 222 may be sized slightly larger than the substrate
in a stepwise or sloped fashion and facilitates alignment and/or
centering of the substrate 140 when the substrate support 104 is
raised. The substrate may then be seated on the support lip 219 and
substrate centering is maintained during lifting and/or rotation of
the substrate support 104. The support ring 210 may also include an
outer wall 223 that extends downward from the upper surface of the
support ring 210 opposite the inner wall 222. The area between the
outer wall 223 and inner wall 222 forms a channel 224 that
facilitates alignment of the support ring 210 on the annular
extension 214. The support section 212 may be coupled to the
magnetic ring section 208 by fastening, bonding, or
gravitationally, and is adapted to support the substrate 140 during
processing. In one embodiment, the support ring 210 functions as an
edge ring and may be gravitationally attached to the annular
extension 214 for easy removal and replacement.
[0041] The support section 212 may be fabricated from a material
that reduces potential scratching, chemical or physical
contamination, and/or marring of the substrate, for example,
materials such as silicon carbide, stainless steel, aluminum,
ceramic, or a high temperature polymer may be used. Alternatively,
the support section 212 may be fabricated as a unitary member from
the material of the magnetic ring section 208. At least a portion
of the support section 212 may be fabricated or coated with a
reflective material, or made of or coated with a black material to
absorb heat similar to a black body, depending on process
parameters. It is to be noted that a black material as used herein
may include dark colors, such as the color black, but is not
limited to dark colored materials or coatings. More generally, a
black material, a black finish, or a black coating refers to the
lack of reflectivity or the ability the material, finish, or
coating to absorb energy, such as heat and/or light, similar to a
black body.
[0042] FIG. 3 is a schematic side view of another embodiment of an
RTP chamber 300 which includes a chamber body 102, having walls
108, a bottom 110, and a top 112, defining an interior volume 120
as in FIG. 1. The chamber 300 also includes a contactless or
magnetically levitated substrate support 104 as in FIG. 1, but the
stator and other components outside the chamber 200 are not shown
for clarity. In this embodiment, the substrate support 104 is
depicted in an exchange position, wherein the plurality of lift
pins 144 are supporting the substrate 140 to facilitate transfer of
the substrate.
[0043] In this embodiment, a portion of the substrate support 104
and/or the magnetic ring section 208 may rest at or near an upper
surface of the bottom 110 of the chamber body 102, and the window
114 is supported by one of the upper surface of the magnetic ring
section 208 and/or an extension 312 coupled to or otherwise
supported by the upper surface of the bottom 110. The extension 312
may be sidewalls of a coolant assembly 360 around a portion of the
radiant heat source 106 disposed in the inside diameter of the
substrate support 104, or the extensions 312 may be support members
coupled to the upper surface of the bottom 110 within the inside
diameter of the substrate support 104 and outside of the coolant
assembly 360. An adaptor plate 315 may also be coupled to the
chamber bottom 110 to facilitate connection of wires and other
support devices for the radiant heat source 106 and/or the coolant
assembly 360.
[0044] The support section 212 may be an annular extension 214
extending from an upper surface of the substrate support 104 or the
magnetic ring section 208. The support section 212 may also include
a support ring 210 that provides alignment and a seating surface
for the substrate 140. The support ring 210 includes an inner wall
222 and a support lip 219 extending inwardly from the inner wall
222. The inner wall 222 may be sized slightly larger than the
substrate and facilitates alignment and/or centering of the
substrate 140 when the substrate support 104 is raised. The
substrate 140 may then be seated on the support lip 219 and
substrate centering is maintained during lifting and/or rotation of
the substrate support 104.
[0045] In one embodiment, the cooling block 180 includes a
plurality of coolant channels 348A-348C for circulating a cooling
fluid as described above. The coolant channels may be separate
channels or discrete flow paths, or the coolant channels may
comprise a plurality of closed flow paths coupled to the coolant
source 182. In one embodiment, the cooling block 180 comprises
multiple cooling zones, such as an outer zone defined generally by
the coolant channel 348A, an inner zone defined generally by
coolant channel 348C, and an intermediate zone generally defined by
coolant channel 348B. The outer zone may correspond to the
periphery of the substrate 140 while the inner and intermediate
zones may correspond to a central portion of the substrate 140. The
coolant temperature and/or coolant flow may be controlled in these
zones to provide, for example, more cooling on the periphery of the
substrate 140 relative to the center of the substrate. In this
manner, the cooling block 180 may provide enhanced temperature
control of the substrate 140 by providing more or less cooling in
regions of the substrate where cooling is needed or desired.
[0046] The cooling block 180 may be formed from a material such as
aluminum, stainless steel, nickel, a ceramic, or a process
resistant polymer. The cooling block 180 may comprise a reflective
material, or include a reflective coating configured to reflect
heat onto the substrate surface. Alternatively, the cooling block
180 may comprise a black material (such as a black material
configured to absorb energy substantially similar to a black body)
or otherwise coated or finished with a black material or surface
that is configured to absorb heat from the substrate and/or the
interior volume 120. The cooling block 180 may also include a face
or outer surface 332 that may be roughened or polished to promote
reflectivity or absorption of radiant energy in the form of heat
and/or light. The outer surface 332 may also include a coating or
finish to promote reflectivity or absorption, depending on the
process parameters. In one embodiment, the cooling block 180 may be
a black material or a material resembling a black material, or
otherwise coated or finished with a black material or resembling a
black material, to have an emissivity or emittance near 1, such as
an emissivity between about 0.70 to about 0.95.
[0047] As shown in FIG. 3, the interior volume 120 comprises a
temperature transition zone 305, or processing zone depicted as
distance D.sub.3, which includes a heating region 306A and a
cooling region 306B that the substrate 140 may be exposed to during
processing. The regions 306A, 306B enable rapid heating and rapid
cooling of the substrate 140 during processing in the interior
volume 120. As an example, heating region 306A may enable a
temperature on the face of the substrate 140 that is between about
450.degree. C. to about 1400.degree. C. during processing, and the
cooling zone 306B may cool the face of the substrate 140 to about
room temperature or lower during processing, depending on process
parameters.
[0048] For example, the substrate may be transferred to the RTP
chamber at room temperature, or some temperature above room
temperature provided by a heating means in a load lock chamber, or
other peripheral chamber or transfer device. The temperature of the
substrate before, during, or after transfer of the substrate to the
RTP chamber may be referred to as the first or introduction
temperature, from which the RTP process may be initiated. In one
embodiment, the introduction temperature may be between about room
temperature, to about 600 C. Once the substrate is introduced to
the chamber, the substrate may be rapidly heated, taking the
temperature of the substrate from the introduced temperature to a
second temperature of between about 800.degree. C. to about
1200.degree. C., such as about 900.degree. C. to about 1150.degree.
C. In one embodiment, power to the radiant heat source is varied
and monitored, using feedback from the sensors 117, to enable a
second temperature of about 900.degree. C. to about 1150.degree. C.
across the substrate in a heating step or first heating period.
[0049] In one embodiment, the first heating period is configured to
raise the temperature of the substrate from the introduction
temperature to about 900.degree. C. to about 1150.degree. C. across
the substrate in about 2 minutes or less, such as between about 50
seconds and about 90 seconds, for example, between about 55 seconds
and about 75 seconds. After the substrate has reached the second
temperature in the heating period, a spike or transition period may
begin, which includes a second heating period. The second heating
period may include heating the substrate to a third temperature of
about 25.degree. C. to about 100.degree. C. higher than the second
temperature. The transition period also includes lowering the
temperature of the substrate to a fourth temperature, which is
about 25.degree. C. to about 100.degree. C. lower than the third
temperature. In one embodiment, the third temperature and the
fourth temperature are within about 5.degree. C. to about
20.degree. C. of each other, and in another embodiment, the third
temperature and the fourth temperature are substantially equal. The
transition period may include a third period of about 3 seconds or
less, such as about 0.1 seconds to about 2 seconds, for example,
between about 0.3 seconds to about 1.8 seconds.
[0050] After the transition period, the substrate may be placed
adjacent the cooling block 180 and rapidly cooled by one or both of
the cooling block 180 and coolant source 315 (described in more
detail below). The substrate may be cooled to a temperature
substantially equal to the first or introduction temperature in a
fourth period that may be less than 10 seconds, such as about 2
seconds to about 6 seconds. The substrate may be cooled rapidly to
a desired temperature, including a temperature at or near room
temperature, or be cooled to a temperature above room temperature
that enables transfer, which may enhance throughput.
[0051] The rapid heating and cooling of the substrate, as described
above, provides many benefits. The temperature of the substrate is
constantly monitored by feed back from the sensors 117, and
enhanced control of the substrate temperature may be facilitated by
moving the substrate relative the cooling block 180 and/or the
radiant heat source 106. Dopant diffusion control may be enhanced
by the rapid and controlled heating and cooling of the substrate,
and device performance may be improved. Additionally, the lessened
heating and cooling times may increase throughput.
[0052] To enable the rapid heating and cooling of the substrate,
the substrate may travel in the temperature transition zone 305.
The travel of the substrate 140 in the interior volume 120 and the
regions 306A, 306B facilitate a sharper transition and/or a lower
residence time between heating and cooling of the substrate. In one
example, once the substrate 140 is placed in a processing position,
the heating region 306A of the temperature transition zone 305 may
include a travel distance D.sub.1 for the substrate 140 (or
substrate support 104), for example, between about 0.5 inches to
about 1.5 inches. The cooling region 306B of the temperature
transition zone may include a travel distance D.sub.2 for the
substrate 140 (or substrate support 104) between about 0.5 inches
to about 1.5 inches. In one embodiment, the total travel of the
substrate 140 (or substrate support 104) within the interior
volume, such as between the radiant heat source 106 and the cooling
block 180, is between about 0.75 inches to about 3.25 inches, for
example, between about 1.0 inches and about 2.75 inches, such as
about 2 inches. In one embodiment, the distance D.sub.1 comprises
about one half of the distance D.sub.3, and the distance D.sub.2
comprises about one half of the distance D.sub.3. The substrate
support 104 may be configured to raise the substrate to a position
that is in close proximity to the substrate 140, depending on the
flatness of the substrate and other physical properties of the
substrate, and the mechanical characteristics of the substrate
support. Assuming the substrate has a suitable flatness, and the
substrate support 104 and substrate disposed thereon is
substantially parallel to the cooling block 180, the substrate may
be raised to be within about 0.005 inches to about 0.025 inches
from the lower surface of the cooling block 180. Bringing the
substrate in close proximity to the cooling block enables rapid
heat transfer and enhanced cooling of the substrate.
[0053] In one embodiment, the chamber 300 includes a gas port 310
coupled to a coolant source 315. The gas port 310 may be a manifold
or a plurality of openings that are formed or otherwise coupled to
the upper portion of the chamber wall 108, and may be formed as, or
adapted to couple to, a nozzle that enables laminar flow through
the cooling region 306B, for example adjacent to the outer surface
332 of the cooling block 180. To enable a more enhanced flow path,
the chamber also includes an exit port 320 formed in the chamber
wall 108, typically opposing the gas port 310. The exit port 320
may be coupled to a vacuum source configured to assist the
atmosphere control system 164 (FIG. 1) and remove excess gas
provided by the gas port 310. The coolant source 315 includes a
cooling fluid, such as helium (He), nitrogen (N.sub.2), or other
suitable cooling fluid, and is directed or configured to flow
within the cooling region 306B. The cooling fluid from the gas port
310 enables more rapid cooling of the substrate 140 when the
substrate is positioned in the cooling region 306B.
[0054] As described in reference to FIG. 1, the radiant heat source
106 is coupled to a coolant assembly 360 that is adapted to
maintain a suitable temperature and/or cool the honeycomb tubes 160
of the radiant heat source 106. The coolant assembly 360 includes
sidewalls 312 and a bottom 314 that is adapted to contain a fluid.
The bottom 314 includes ports 322 and 324 that are configured to
supply and remove coolant fluid from the coolant source 183, which
may be water, ethylene glycol, or other suitable cooling fluid. The
coolant assembly 360 may also include a plurality of fluid channels
formed therein (described in reference to FIG. 4) for enhanced
thermal transfer from the cooling fluid and the radiant heat source
106.
[0055] FIG. 4 is partial side view of another embodiment of an RTP
chamber 400 in a processing position and details of the coolant
assembly 360 will be described. The coolant assembly 360 includes a
bottom 322 and sidewalls 312 as shown in other Figures, and also
includes a body 427, which comprises a plurality of partitions 426
separating the plurality of honeycomb tubes 160. The body may also
comprise a plate 423 opposing the bottom 322, to form a void 446
therebetween, which is configured to contain the coolant from a
first coolant source 485A and separate the void 446 from the
plurality of honeycomb tubes 160. The void 446 is in communication
with the coolant source 485A by a port 324 coupled to the bottom
322 and the port 324 is in communication with a plenum 445 that is
in fluid communication with the void 446 by a plenum port 415. The
plate 423 may include a plurality of channels or grooves 428 formed
therein to increase the surface area available to the cooling
fluid, thus enhancing heat dissipation from the radiant heat source
106.
[0056] In operation, a cooling fluid is supplied from the first
source 485A to the void 446 by the port 322, and the coolant at
least partially fills the void 446. The coolant may be continually
flowed into the void to dissipate heat and exits the void through
the plenum port 415 to the plenum 445. The coolant may be removed
from the plenum 445 by the port 324 and returned to the first
source 485A. The coolant may be replenished and/or cooled before
cycling through the void 446. In this manner, the temperature of
the radiant heat source 106 is controlled.
[0057] The coolant assembly 360 may also includes a plurality of
fluid channels 425 formed in at least a portion of the plurality of
partitions 426. The fluid channels 425 are configured to flow a
cooling fluid, such as water, ethylene glycol, nitrogen (N.sub.2),
helium (He), or other fluid used as a heat exchange medium, from a
second fluid source 485B. The fluid channels 425 are coupled to the
second fluid source 485B by at least one inlet and outlet (not
shown). The flowing of coolant from the first and second sources
485A, 485B facilitates enhanced temperature control of the radiant
heat source 106.
[0058] The chamber 100 also includes a magnetically levitated or
contactless substrate support 104 having a support member 210 and
an annular extension 212 coupled to an annular body 220 disposed in
a channel or trough 412. The trough 412 is coupled to a fluid
source 186 through a port 420 for supplying a coolant to the trough
412, thus dissipating heat that may be transferred from the radiant
heat source 106 and/or heat created by rotation of the annular body
220 during processing. The fluid source 186 may include cooling
fluids, such as water, ethylene glycol, nitrogen (N.sub.2), helium
(He), or other fluid used as a heat exchange medium. A gap 418 may
also be formed between the sidewall 312 of the coolant assembly 360
and a sidewall of the trough 412 to facilitate insulation between
the annular body 220 of the substrate support 104 and the radiant
heat source 106.
[0059] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *