U.S. patent application number 13/284348 was filed with the patent office on 2013-05-02 for apparatus for sublimating solid state precursors.
This patent application is currently assigned to APPLIED MATERIALS, INC.. The applicant listed for this patent is David K. CARLSON, Satheesh KUPPURAO, Errol Antonio C. SANCHEZ. Invention is credited to David K. CARLSON, Satheesh KUPPURAO, Errol Antonio C. SANCHEZ.
Application Number | 20130105483 13/284348 |
Document ID | / |
Family ID | 48168312 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130105483 |
Kind Code |
A1 |
CARLSON; David K. ; et
al. |
May 2, 2013 |
APPARATUS FOR SUBLIMATING SOLID STATE PRECURSORS
Abstract
In some embodiments, an apparatus for sublimating solid state
precursors may include a container having a body, lid, and
removable bottom, wherein the removable bottom is sealable to the
body to seal the container when coupled to the body; a tray
insertable into the container from a bottom of the container, the
tray comprising: a gas permeable base to support a solid state
precursor, the gas permeable base having a through hole disposed
proximate the center of the gas permeable base; an outer ring
disposed around an outer edge of the base and extending upwardly
from the base, the outer ring configured to interface with the lid
of the container; and an inner ring disposed within the through
hole, the inner ring configured to interface with the lid of the
container; an inlet disposed through the lid of the container; and
an outlet disposed through the lid of the container.
Inventors: |
CARLSON; David K.; (San
Jose, CA) ; SANCHEZ; Errol Antonio C.; (Tracy,
CA) ; KUPPURAO; Satheesh; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CARLSON; David K.
SANCHEZ; Errol Antonio C.
KUPPURAO; Satheesh |
San Jose
Tracy
San Jose |
CA
CA
CA |
US
US
US |
|
|
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
48168312 |
Appl. No.: |
13/284348 |
Filed: |
October 28, 2011 |
Current U.S.
Class: |
220/367.1 |
Current CPC
Class: |
C23C 16/4483 20130101;
C23C 16/4488 20130101; C30B 23/00 20130101 |
Class at
Publication: |
220/367.1 |
International
Class: |
B65D 51/16 20060101
B65D051/16 |
Claims
1. An apparatus for sublimating solid state precursors, comprising:
a container having a body, a lid, and a removable bottom, wherein
the removable bottom is sealable to the body to seal the container
when coupled to the body; a tray insertable into the container from
a bottom of the container, the tray comprising: a gas permeable
base to support a solid state precursor, the gas permeable base
having a through hole disposed proximate the center of the gas
permeable base; an outer ring disposed around an outer edge of the
base and extending upwardly from the base, the outer ring
configured to interface with the lid of the container; and an inner
ring disposed within the through hole, the inner ring configured to
interface with the lid of the container; an inlet disposed through
the lid of the container, the inlet configured to provide a gas
through the inner ring of the tray to an area beneath the tray; and
an outlet disposed through the lid of the container to allow a
gaseous form of the solid state precursor to flow out of the
container.
2. The apparatus of claim 1, wherein the tray comprises a plurality
of trays stacked atop one another, and wherein the outer ring of
each of the plurality of trays is configured to interface with the
outer ring of another tray disposed directly atop the tray or the
lid of the container and the inner ring of each of the plurality of
trays is configured to interface with the inner ring of another
tray disposed directly atop the tray or the lid of the container
and wherein the area beneath the tray is an area beneath a bottom
most tray of the plurality of trays.
3. The apparatus of claim 2, wherein each of the outer ring and
inner ring comprises an outwardly extending tab configured to
interface with a cavity formed in each of the outer ring and the
inner ring of another tray disposed directly atop the tray or the
lid of the container.
4. The apparatus of claim 1, further comprising: a temperature
control unit disposed through the inner ring of the tray to control
a temperature within the container.
5. The apparatus of claim 4, wherein the temperature control unit
comprises at least one of a heater or a plurality of conduits
configured to allow the flow of a heat transfer fluid within the
temperature control unit.
6. The apparatus of claim 1, wherein the container is fabricated
from stainless steel, a nickel-chromium alloy, or quartz.
7. The apparatus of claim 1, further comprising a shell disposed
around the container.
8. The apparatus of claim 7, wherein the shell may comprise at
least one of an insulative material, a heater, or a plurality of
conduits configured to allow the flow of a heat transfer fluid
within the shell to control over a temperature of the container by
increasing or decreasing a transfer of heat from the container
during use.
9. The apparatus of claim 7, further comprising a liner disposed
between the shell and an outer surface of the container.
10. The apparatus of claim 9, wherein the liner is fabricated from
quartz.
11. The apparatus of claim 1, wherein the gas permeable base
comprises pores having a diameter of about 25 to 150 microns.
12. The apparatus of claim 11, wherein the gas permeable base
comprises a quartz frit or stainless steel frit.
13. The apparatus of claim 1, wherein the inner ring and outer ring
are fabricated from stainless steel or quartz.
14. The apparatus of claim 1, further comprising a pressure monitor
coupled to each tray to monitor a gas pressure within each
tray.
15. The apparatus of claim 1, further comprising a pressure monitor
coupled to the inlet and the outlet to monitor a pressure within
the container.
16. The apparatus of claim 1, further comprising a heater coupled
to the inlet and outlet to control a temperature within the inlet
and outlet.
17. The apparatus of claim 1, further comprising a gas manifold
disposed beneath the bottom shelf and coupled to a terminal end of
the gas conduit, the gas manifold configured to receive the gas and
evenly distribute the gas proximate the bottom of the
container.
18. An apparatus for sublimating solid state precursors,
comprising: a container having a body, a lid, and a removable
bottom that is sealable to the body to seal the container when
coupled to the body; a first tray insertable into the container
from a bottom of the container, the first tray comprising a gas
permeable base to support a solid state precursor and having a
central opening formed through the base, an inner wall disposed
about the central opening of the base, and an outer wall disposed
about an outer edge of the base, wherein the inner and outer walls
interface with the lid of the container to provide an airtight seal
between the first tray and the lid; an inlet, disposed through the
lid of the container and coupled to an inlet channel passing
through the central opening of the base and defined at least in
part by the inner wall of the first tray, to provide a gas to an
area beneath the first tray; and an outlet, disposed through the
lid of the container in a region generally above a region of the
first tray between the inner and outer walls of the first tray, to
allow a gaseous form of the solid state precursor to flow out of
the container.
19. The apparatus of claim 18, further comprising: at least a
second tray disposed below the first tray and having a gas
permeable base to support a solid state precursor and having a
central opening formed through the base, an inner wall disposed
about the central opening of the base, and an outer wall disposed
about an outer edge of the base, wherein the inner and outer walls
of the second tray interface with the inner and outer walls of the
first tray to provide an airtight seal between the first tray and
the second tray, and wherein the inlet channel further passes
through the central opening of the base of the second tray such
that the area beneath the first tray where the gas is provided to
is beneath the second tray.
20. The apparatus of claim 18, further comprising: a temperature
control unit disposed within the container to control a temperature
within the container.
Description
FIELD
[0001] Embodiments of the present invention generally relate to
semiconductor processing.
BACKGROUND
[0002] The inventors have observed that conventionally used
precursor systems (e.g., gas, liquid vapor, liquid w/inert gas
carrier, solid evaporation, solid sublimation, reactive carrier,
etc.) used for deposition processes (e.g., epitaxial growth or
atomic layer deposition processes) provide precursors that are not
of sufficient purity for current semiconductor processing
requirements. Moreover, pre-prepared precursors conventionally used
are unstable and may decompose, condense, or change states with
time.
[0003] Therefore, the inventors have provided an improved apparatus
for delivering precursors having an improved purity as compared to
conventionally generated precursors.
SUMMARY
[0004] Apparatus for sublimating solid state precursors are
provided herein. In some embodiments, an apparatus for sublimating
solid state precursors may include a container having a body, a
lid, and a removable bottom, wherein the removable bottom is
sealable to the body to seal the container when coupled to the
body; a tray insertable into the container from a bottom of the
container--wherein the tray may include a gas permeable base to
support a solid state precursor, the gas permeable base having a
through hole disposed proximate the center of the gas permeable
base; an outer ring disposed around an outer edge of the base and
extending upwardly from the base, the outer ring configured to
interface with the lid of the container; and an inner ring disposed
within the through hole, the inner ring configured to interface
with the lid of the container--an inlet disposed through the lid of
the container, the inlet configured to provide a gas through the
inner ring of the tray to an area beneath the tray; and an outlet
disposed through the lid of the container to allow a gaseous form
of the solid state precursor to flow out of the container.
[0005] In some embodiments, an apparatus for sublimating solid
state precursors may include a container having a body, a lid, and
a removable bottom that is sealable to the body to seal the
container when coupled to the body; a first tray insertable into
the container from a bottom of the container, the first tray
comprising a gas permeable base to support a solid state precursor
and having a central opening formed through the base, an inner wall
disposed about the central opening of the base, and an outer wall
disposed about an outer edge of the base, wherein the inner and
outer walls interface with the lid of the container to provide an
airtight seal between the first tray and the lid; an inlet,
disposed through the lid of the container and coupled to an inlet
channel passing through the central opening of the base and defined
at least in part by the inner wall of the first tray, to provide a
gas to an area beneath the first tray; and an outlet, disposed
through the lid of the container in a region generally above a
region of the first tray between the inner and outer walls of the
first tray, to allow a gaseous form of the solid state precursor to
flow out of the container.
[0006] Other and further embodiments of the present invention are
described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Embodiments of the present invention, briefly summarized
above and discussed in greater detail below, can be understood by
reference to the illustrative embodiments of the invention depicted
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.
[0008] FIG. 1 depicts a process chamber suitable for use with an
apparatus for sublimating solid state precursors in accordance with
some embodiments of the present invention.
[0009] FIG. 2 depicts an apparatus for sublimating solid state
precursors in accordance with some embodiments of the present
invention.
[0010] FIG. 3 depicts a tray for use in an apparatus for
sublimating solid state precursors in accordance with some
embodiments of the present invention.
[0011] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. The figures are not drawn to scale
and may be simplified for clarity. It is contemplated that elements
and features of one embodiment may be beneficially incorporated in
other embodiments without further recitation.
DETAILED DESCRIPTION
[0012] Apparatus for sublimating solid state precursors are
provided herein. In some embodiments, the inventive apparatus may
advantageously provide one or more solid state precursor supporting
trays that are easily installed and removed from the apparatus,
thereby providing an easier and more efficient mechanism for
providing solid state precursors to a solid state precursor
sublimation system as compared to conventional precursor
sublimation systems. The inventive apparatus may further
advantageously provide a point of use generation of precursors,
thereby reducing the risk of the precursor condensing, changing
state or reacting with the distribution system. The inventive
apparatus may further advantageously provide a pressure gradient
within the apparatus to facilitate more uniform sublimation of a
solid state precursor, thereby providing improved process
consistency and material utilization. Although not intended to be
limiting in scope, the inventors have observed that the inventive
apparatus may be utilized to provide precursors for epitaxial and
atomic layer deposition processes.
[0013] FIG. 1 depicts a schematic side view of a process chamber
100 suitable for use with an apparatus for sublimating solid state
precursors in accordance with some embodiments of the present
invention. In some embodiments, the process chamber 100 may be a
commercially available process chamber, such as the RP EPI.RTM.
reactor, available from Applied Materials, Inc. of Santa Clara,
Calif., or any suitable semiconductor process chamber adapted for
performing epitaxial silicon deposition processes that has been
modified for use with the precursor delivery apparatus as described
herein. Other process chambers may also be used, however.
[0014] The process chamber 100 may generally comprise a chamber
body 110, support systems 130, and a controller 140. An apparatus
for sublimating solid state precursors 180 may be coupled to the
process chamber 100 via, for example, a process gas intake port, or
inlet 114. The apparatus for sublimating solid state precursors 180
may generally be utilized to sublimate any compatible type of solid
state precursor needed for a desired application, for example, such
as the exemplary solid state precursors described below.
[0015] The chamber body 110 generally includes an upper portion
102, a lower portion 104, and an enclosure 120. A vacuum system 123
may be coupled to the chamber body 110 to facilitate maintaining a
desired pressure within the chamber body 110. In some embodiments,
the vacuum system 123 may comprise a throttle valve (not shown) and
vacuum pump 119 which are used to exhaust the chamber body 110. In
some embodiments, the pressure inside the chamber body 110 may be
regulated by adjusting the throttle valve and/or vacuum pump 119.
The upper portion 102 is disposed on the lower portion 104 and
includes a lid 106, a clamp ring 108, a liner 116, a baseplate 112,
one or more upper heating lamps 136 and one or more lower heating
lamps 152, and an upper pyrometer 156. In some embodiments, the lid
106 has a dome-like form factor, however, lids having other form
factors (e.g., flat or reverse curve lids) are also contemplated.
The lower portion 104 is coupled to a process gas intake port 114
and an exhaust port 118 and comprises a baseplate assembly 121, a
lower dome 132, a substrate support 124, a pre-heat ring 122, a
substrate lift assembly 160, a substrate support assembly 164, one
or more upper heating lamps 138 and one or more lower heating lamps
154, and a lower pyrometer 158. Although the term "ring" is used to
describe certain components of the process chamber 100, such as the
pre-heat ring 122, it is contemplated that the shape of these
components need not be circular and may include any shape,
including but not limited to, rectangles, polygons, ovals, and the
like.
[0016] During processing, the substrate 101 is disposed on the
substrate support 124. The lamps 136, 138, 152, and 154 are sources
of infrared (IR) radiation (e.g., heat) and, in operation, generate
a pre-determined temperature distribution across the substrate 101.
The lid 106, the clamp ring 108, and the lower dome 132 are formed
from quartz; however, other IR-transparent and process compatible
materials may also be used to form these components.
[0017] The substrate support assembly 164 generally includes a
support bracket 134 having a plurality of support pins 166 coupled
to the substrate support 124. The substrate lift assembly 160
comprises a substrate lift shaft 126 and a plurality of lift pin
modules 161 selectively resting on respective pads 127 of the
substrate lift shaft 126. In one embodiment, a lift pin module 161
comprises an optional upper portion of the lift pin 128 is movably
disposed through a first opening 162 in the substrate support 124.
In operation, the substrate lift shaft 126 is moved to engage the
lift pins 128. When engaged, the lift pins 128 may raise the
substrate 101 above the substrate support 124 or lower the
substrate 101 onto the substrate support 124.
[0018] The support systems 130 include components used to execute
and monitor pre-determined processes (e.g., growing epitaxial
films) in the process chamber 100. Such components generally
include various sub-systems. (e.g., gas panel(s), gas distribution
conduits, vacuum and exhaust sub-systems, and the like) and devices
(e.g., power supplies, process control instruments, and the like)
of the process chamber 100. These components are well known to
those skilled in the art and are omitted from the drawings for
clarity.
[0019] The controller 140 may be provided and coupled to the
process chamber 100 for controlling the components of the process
chamber 100. The controller 140 may be any suitable controller for
controlling the operation of a substrate process chamber. The
controller 140 generally comprises a Central Processing Unit (CPU)
142, a memory 144, and support circuits 146 and is coupled to and
controls the process chamber 100 and support systems 130, directly
(as shown in FIG. 1) or, alternatively, via computers (or
controllers) associated with the process chamber and/or the support
systems.
[0020] The CPU 142 may be any form of a general purpose computer
processor that can be used in an industrial setting. The support
circuits 146 are coupled to the CPU 142 and may comprise cache,
clock circuits, input/output subsystems, power supplies, and the
like. Software routines, such as the methods for processing
substrates disclosed herein, for example with respect to FIG. 2
below, may be stored in the memory 144 of the controller 140. The
software routines, when executed by the CPU 142, transform the CPU
142 into a specific purpose computer (controller) 140. The software
routines may also be stored and/or executed by a second controller
(not shown) that is located remotely from the controller 140.
Alternatively or in combination, in some embodiments, for example
where the process chamber 100 is part of a multi-chamber processing
system, each process chamber of the multi-chamber processing system
may have its own controller for controlling portions of the
inventive methods disclosed herein that may be performed in that
particular process chamber. In such embodiments, the individual
controllers may be configured similar to the controller 140 and may
be coupled to the controller 140 to synchronize operation of the
process chamber 100.
[0021] A gas source 117 may be coupled to the apparatus for
sublimating solid state precursors 180 to provide one or more gases
to facilitate sublimation of the solid state precursor and/or
delivery of the sublimated precursor (e.g., as described below).
For example, in some embodiments, the gas source 117 may provide a
reactive gas, such as hydrogen (H.sub.2), hydrogen chloride (HCl),
chorine (Cl.sub.2), bromine (Br), oxygen (O.sub.2), methane
(CH.sub.4), or the like. Alternatively, or in combination, in some
embodiments the gas source may provide an inert gas or a carrier
gas, for example such as helium (He), argon (Ar), xenon (Xe), or
the like.
[0022] Referring to FIG. 2, the apparatus for sublimating solid
state precursors 180 may generally comprise a container 210, one or
more trays 208 (four trays shown), an inlet 230 and an outlet
232.
[0023] The container 210 generally comprises a body 206, a lid 226
and a removable bottom 228 configured to seal the container 210
when the bottom 228 is coupled to the body 206. In some
embodiments, the lid 226 may include an inlet 230 to provide a gas
to the container 210 and an outlet 232 to allow a gaseous form of a
solid state precursor to flow out of the container 210. In some
embodiments, each of the inlet 230 and outlet 232 may include or
may be coupled to a temperature control mechanism 246, 248 (e.g., a
heater) to control a temperature of the gases flowing through each
of the inlet 230 and outlet 232. In some embodiments, a pressure
gauge (e.g., 247, 249) may be coupled to each of the inlet 230 and
outlet 232 to allow the pressure of within the container 210 to be
monitored. By monitoring the pressure within the container 210, the
amount of precursor within the container 210 may also be monitored.
The container 210 may be fabricated from any material that is
non-reactive with the precursor (e.g., the precursors discussed
below) to be sublimed. For example, in some embodiments, the
container 210 may be fabricated from quartz or stainless steel.
[0024] The one or more trays 208 are insertable into the container
210 from the bottom 231 of the container 210. By configuring the
one or more trays in such a manner, the inventors have observed
that the one or more trays 208 may be easily and quickly provided
to, and removed from, the apparatus for sublimating solid state
precursors 180, thereby providing an easier and more efficient
mechanism for providing solid state precursors to the solid state
precursor sublimation system 180, as compared to conventional
precursor sublimation systems.
[0025] Although four trays 208 are shown, any number of trays 208
needed to perform a desired sublimation process may be provided.
For example, in some embodiments, less than four, such as one, two,
or three trays 208 may be provided. Alternatively, in some
embodiments, more than four trays 208 may be provided.
[0026] Each tray 208 generally comprises a gas permeable base 242
having a through hole 243, an outer ring 222 (or outer wall)
disposed about an outer edge 219 of the gas permeable base 242 and
an inner ring 240 (or inner wall) disposed within the through hole
243. The outer ring 222 and inner ring 240 may be fabricated from
any material that is non-reactive with the particular precursors
used (e.g., the precursors discussed below) to be sublimed. For
example, in some embodiments, the outer ring 222 and inner ring 240
may be fabricated from quartz or stainless steel. In some
embodiments, the outer ring 222 and inner ring 240 may interface
with the lid 226 of the container 210 to provide an airtight seal
between the tray 208 and the lid 226 to facilitate a flow of gas
(e.g., sublimed precursor) towards the outlet 232. Alternatively,
or in combination, in some embodiments, for example, where the
apparatus for sublimating solid state precursors 180 comprises a
plurality of trays 208 stacked atop one another within the
container 210 (e.g., as depicted in FIG. 2), each of the outer ring
222 and inner ring 240 may interface with an outer ring 222 and
inner ring 240 of a another tray disposed directly atop the tray
208. For example, in some embodiments, such as depicted in FIG. 3,
the outer ring 222 and the inner ring 240 may each comprise a base
portion (e.g., base portion 302, 306) having an outwardly extending
tab 304, 308 protruding from the corresponding base portion. The
outwardly extending tabs 304, 308 may be configured to interface
with a corresponding cavity formed in the bottom of the base
portion (e.g., cavity 310, 312) of another tray disposed to
facilitate an airtight seal between the trays 208 when stacked one
atop another.
[0027] The inventors have observed that conventional precursor
ampoules heated by an external heat source typically display slow
temperature response time due to poor thermal coupling.
Accordingly, and referring back to FIG. 2, in some embodiments, a
temperature control unit 224 may be disposed within an annulus 241
formed by the inner ring 240 to facilitate controlling a
temperature within the container 210 and/or within each tray 208
disposed within the container 210. By controlling the temperature
from within the container (i.e. within the annulus 241 as shown in
the figure), the inventors have observed that the temperature
response time is improved over conventional methods of heating a
precursor ampoule, thereby providing an improved control of the
temperature as compared to those conventional methods.
[0028] The temperature control unit 224 may comprise any mechanism
suitable to control the temperature within the container 210. For
example, in some embodiments, the temperature control unit 224 may
comprise an active temperature control system, for example a
heater, such as a resistive heater. Alternatively, or in
combination, in some embodiments, the temperature control unit 224
may comprise a passive temperature control system, for example,
such as a series of conduits configured to allow a flow of a
temperature control fluid through the temperature control unit
224.
[0029] The gas source 117 provides the one or more gases (e.g., the
one or more gases discussed above) to the annulus 251 via the inlet
230 which flow to an area 213 beneath a bottom most tray (e.g. tray
215) of the one or more trays 208. For example, in some
embodiments, an inlet channel may pass through the central opening
of the base of the tray. The inlet channel may is defined at least
in part by the inner walls, or inner rings, of the trays 208, to
provide the one or more gases to the area beneath the tray. In some
embodiments, a gas manifold 212 may be disposed within the area 213
beneath a bottom most tray 215 and coupled to the annulus to
provide a uniform distribution of the gases to the one or more
trays 208. The gas manifold 212 may be fabricated from any material
that is non-reactive to the gases provided by the gas source, for
example, such as quartz or stainless steel.
[0030] The gas permeable base 242 supports the solid state
precursor and allows the sublimated solid state precursor to pass
through. The gas permeable base 242 may comprise any materials
suitable to allow a flow of gas (e.g., the sublimed precursor)
through the gas permeable base 242. For example, in some
embodiments, the gas permeable base 242 may comprise a frit, for
example such as a quartz frit or stainless steel frit. In such
embodiments, the frit may comprise any pore size suitable to allow
the flow of sublimed precursor through the frit while substantially
preventing larger particles of the solid precursor from passing
through the gas permeable base 242. For example, in some
embodiments, the frit may comprise a pore size of about 25 to about
150 microns, or in some embodiments, about 100 microns.
[0031] In some embodiments, by varying the pore size of the gas
permeable base 242 of each tray 208, the pressure within each tray
208 may be controlled, thereby allowing the rate of sublimation of
the solid state precursor within each tray 208 to be controlled.
For example, as the pore size of the gas permeable base 242 of the
tray 208 decreases, the pressure within the tray increases and the
reaction rate of the precursor within the tray decreases.
[0032] The inventors have observed that in conventional precursor
sublimating systems using multiple stages (e.g., shelves), the
solid state precursor in the first stages are consumed from the
first stages at a higher rate than the later stages. Because of
this disparity in rate of consumption of the solid state precursor
and the changing of the packing of the solid state precursor over
time, the solid state precursor in the later stages need to be
impacted in order to settle the material and recover sublimation
rate, thereby making the process inefficient. Accordingly, the
inventors have observed that by creating a pressure gradient (e.g.,
by varying the pore size of the gas permeable base 242 of each tray
208) across the trays 208 wherein the lowest tray of the trays 208
has the highest pressure and the highest tray of the trays 208 has
the lowest pressure, the rate of consumption of the solid state
precursor in each tray 208 may be more uniform, thereby providing a
more consistent sublimation rate across all of the trays and
allowing maximum solid state precursor utilization prior to
refilling or replacing the trays 208, thus improving process
consistency and increasing the efficiency of the sublimation
process.
[0033] In some embodiments, a cover frit (shown in phantom at 245)
may be disposed atop the gas permeable base 242. The cover frit 245
may be fabricated from the same, or in some embodiments, a
different, material than that of the gas permeable base 242
discussed above. In addition, the cover frit 245 may comprise any
pore size suitable to allow the flow of sublimed precursor through
the cover frit 245, for example, such as within the pore size range
discussed above with respect to the gas permeable base 242. When
present, the solid state precursor may be disposed between the gas
permeable base 242 and the cover frit 245, thereby allowing the
tray 208 to be "pre-charged" or loaded with the precursor prior to
use. In some embodiments, the pre-filled tray may be hermitically
sealed to reduce exposure of the precursor to an atmosphere outside
of the container 210, thereby increasing stability and decreasing
decomposition of the precursor. In such embodiments, the hermetic
seal may be broken (e.g., the tray may be unpackaged) prior to use
of the tray.
[0034] In some embodiments, a pressure monitor (pressure monitors
220, 221, 223, 225, 227) may be coupled to each of the one or more
trays 208 to monitor an inter-stage pressure (pressure within each
of the one or more trays 208). By monitoring the pressure at each
of the one or more trays 208, the amount of precursor disposed on
each of the one or more trays 208 may be monitored.
[0035] In some embodiments, a shell 202 may be disposed around an
outer surface 234 of the container 210. The shell 202 generally
comprises a body 206, bottom 216, and an optional top (shown in
phantom at 236). In some embodiments a seal 218 may disposed
between the bottom 216 and body 206 and/or the top 236 and body 206
to provide a vacuum seal between the components of the shell 202.
The seal 218 may be any type of seal, for example, such as an
o-ring fabricated from, for example, a high temperature resistant
polymer, such as polytetrafluoroethylene (PTFE).
[0036] When present, the shell 202 may facilitate enhanced control
over a temperature of the container by increasing or decreasing a
rate of heat transfer to or from the container 210 during use. For
example, in some embodiments, the shell 202 may comprise an
insulative material to reduce heat loss from the container 210,
thus allowing the container 210 maintained at a higher temperature
while not requiring additional heating. Alternatively, or in
combination, the shell 202 may provide an active heating or cooling
of the container 210. For example, in some embodiments, the shell
202 may include one or more conduits disposed within the shell and
configured to allow a flow of a heat transfer fluid through the
shell 202. Alternatively, or in combination, in some embodiments,
the shell 202 may comprise one or more embedded heaters, such as
resistive heaters or the like. In some embodiments, an external
heat source, such as an IR lamp, may be disposed external to the
shell 202 to provide heat energy to the shell 202. In some
embodiments, a liner 204 may be disposed between the shell 202 and
container 210. The liner 204 may be fabricated from any material
suitable to provide a desired amount of heat transfer, for example,
such as quartz.
[0037] In preparation of the apparatus for sublimating solid state
precursors 180, first the one or more trays 208 are loaded with a
solid state precursor, such as a powdered, pellet or sintered solid
state precursor. The trays 208 are then stacked atop the bottom
plate 228 and interlocked together (e.g., via mating features such
as the tabs 304, 308 and cavities 310, 312 described above). The
trays 208 and bottom plate 228 may then installed into the body 206
of the container 210. The container 210 may then be optionally
purged and pressurized with an inert gas (e.g., helium (He), argon
(Ar), xenon (Xe), or the like). When pressurized, a sniffing
procedure may be utilized to determine whether the container 210 is
air tight. A pressure drop within the container is then recorded
within the container 310 to provide a baseline pressure to later
determine consumption of the solid state precursor. The apparatus
for sublimating solid state precursors 180 is then installed in the
process system (e.g., coupled to the process chamber 100 described
above). The process parameters (e.g., process gases, pressure and
temperature required for sublimation, or the like) are then
determined and entered into a controller (e.g., controller 140
described above). Initial process conditions of the and the
sublimation process may begin.
[0038] In operation of the apparatus for sublimating solid state
precursors 180, the one or more process gases provided by the gas
source 117 are provided to the annulus 241 formed by the inner ring
240 of the one or more trays 208. The one or more process gases
flow down the annulus 241 to an area 213 beneath a bottom most tray
(e.g. tray 215) of the one or more trays 208 and is distributed to
the bottom most tray. The gas manifold 212 provides a uniform
distribution of the one or more gases to the bottom tray. The one
or more process gases then pass through the gas permeable base 242
and react with, or carry, the sublimated precursor (wherein the
sublimation may be controlled by one or more of a reaction with the
one or more process gases, temperature, or pressure at each tray
208) up the container through each of the one or more trays 208.
The sublimated precursor then flows to the outlet 232 and is
provided to the process chamber 100.
[0039] In an exemplary application of the apparatus for sublimating
solid state precursors 180 described above, in some embodiments,
the apparatus for sublimating solid state precursors 180 may be
utilized to provide a tin (Sn) precursor to a process chamber. The
inventors have observed that tin (Sn) may be utilized as a stressor
in certain deposition process, for example, such as in a germanium
(Ge) based epitaxial or atomic layer deposition (ALD) processes.
However, ultra high purity precursors are not readily available.
Moreover, pre-prepared hydrides of tin (e.g., stannane (SnH.sub.4))
are unstable and organotin compounds contain an impermissibly large
amount of carbon. Accordingly, in some embodiments the apparatus
for sublimating solid state precursors 180 may be utilized as a
point of use precursor source to provide tin (Sn) precursors,
including high purity precursors. For example, in such embodiments
a solid state tin (Sn) precursor may be provided to the trays 208
and a process gas comprising one or hydrogen chloride gas (HCl),
chlorine (Cl.sub.2), deuterium (D) or hydrogen (H.sub.2) may be
provided to the container 210. The tin precursor may be then
generated in accordance with the following equations:
Sn(s)+2HCl(G).fwdarw.SnCL2+H2(G) (1)
Sn(s)+2Cl2(G).fwdarw.SnCl4(G) (2)
Sn(s)+2H2(G).fwdarw.SnH4(G) (3)
Sn(s)+2D(G).fwdarw.SnD4(G) (4)
[0040] In another exemplary application of the apparatus for
sublimating solid state precursors 180 described above, in some
embodiments, the apparatus for sublimating solid state precursors
180 may be utilized to provide a serial conversion for multistep
reactions. In such embodiments, each tray 208 of the apparatus for
sublimating solid state precursors 180 may be utilized to perform
one step of the multistep reaction, or in some embodiments, a
single apparatus for sublimating solid state precursors 180 may be
utilized to perform one step of the multistep reaction. An
exemplary multistep reaction may include a first step of generation
of a precursor, a second step of a conversion of the precursor and
a third step of purifying the precursor. For example, in some
embodiments, the apparatus for sublimating solid state precursors
180 may be utilized to generate a tin precursor (e.g., SnH4) using
lithium aluminum hydrate (LiAlH.sub.4).
[0041] In such embodiments, a solid state tin (Sn) precursor may be
provided to a first tray of the one or more trays 208, lithium
aluminum hydrate LiAlH4 may be provided to a second tray of the one
or more trays 208 and a third tray may be used as a cold trap to
trap unwanted solids. The tin precursor may be then generated in
accordance with the following equations/steps:
Sn(s)+2Cl2(g).fwdarw.SnCl4(G) (1)
SnCl4(G)+LiAlH4(s).fwdarw.SnH4(G)+LiCl(S)+AlCl3(s) (2)
solid AlCl3(s) trapped in upper most tray (3)
[0042] Thus, apparatus for sublimating solid state precursors have
been provided herein. In some embodiments, the inventive apparatus
may advantageously provide one or more solid state precursor
supporting trays that are easily installed and removed from the
apparatus, thereby providing an easier and more efficient mechanism
for providing solid state precursors to a solid state precursor
sublimation system as compared to conventional precursor
sublimation systems. The inventive apparatus may further
advantageously provide a point of use generation of precursors,
thereby reducing the risk of the precursor condensing, changing
state or reacting with the distribution system. The inventive
apparatus may further advantageously provide a pressure gradient
within the apparatus to facilitate uniform sublimation of a solid
state precursor, therefore providing an improved process
consistency and material utilization.
[0043] 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.
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