U.S. patent application number 11/651136 was filed with the patent office on 2007-05-17 for methods, systems, and apparatus for uniform chemical-vapor depositions.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Kie Y. Ahn.
Application Number | 20070107661 11/651136 |
Document ID | / |
Family ID | 25170514 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070107661 |
Kind Code |
A1 |
Ahn; Kie Y. |
May 17, 2007 |
Methods, systems, and apparatus for uniform chemical-vapor
depositions
Abstract
Integrated circuits, the key components in thousands of
electronic and computer products, are generally built layer by
layer on a silicon substrate. One common technique for forming
layers is called chemical-vapor deposition (CVD.) Conventional CVD
systems not only form layers that have non-uniform thickness, but
also have large chambers that make the CVD process wasteful and
slow. Accordingly, the inventor devised new CVD systems, methods,
and apparatuses. One exemplary CVD system includes an outer
chamber, a substrate holder, and a unique gas-distribution fixture.
The fixture includes a gas-distribution surface having holes for
dispensing a gas and a gas-confinement member that engages or
cooperates with the substrate holder to form an inner chamber
within the outer chamber. The inner chamber has a smaller volume
than the outer chamber, which not only facilitates depositions of
more uniform thickness, but also saves gas and speeds up the
deposition process.
Inventors: |
Ahn; Kie Y.; (Chappaqua,
NY) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Micron Technology, Inc.
|
Family ID: |
25170514 |
Appl. No.: |
11/651136 |
Filed: |
January 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10931845 |
Aug 31, 2004 |
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11651136 |
Jan 9, 2007 |
|
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09797324 |
Mar 1, 2001 |
6852167 |
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10931845 |
Aug 31, 2004 |
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Current U.S.
Class: |
118/719 |
Current CPC
Class: |
C23C 16/45525 20130101;
C23C 16/45589 20130101; C23C 16/45544 20130101; C23C 16/45591
20130101; C23C 16/45565 20130101 |
Class at
Publication: |
118/719 |
International
Class: |
C23C 16/00 20060101
C23C016/00 |
Claims
1. A chemical-vapor deposition system comprising: a first chamber
for confining gases; and a second chamber within the first chamber
for at least partially containing a substrate during
deposition.
2. The system of claim 1, wherein the first chamber is a right
cylindrical chamber.
3. The system of claim 1, wherein the second chamber comprises a
surface of a substrate-support structure.
4. The system of claim 3, wherein the second chamber further
comprises a gas-distribution fixture for atomic-layer deposition,
the fixture confronting the surface of the substrate-support
structure and comprising: a non-reactive plate including a
plurality of holes; and a wall surrounding at least a portion of
the plate.
5. The system of claim 1, wherein the second chamber comprises one
or more heating elements operable to heat the substrate, and one or
more temperature sensors operable to monitor a temperature of the
substrate.
6. The system of claim 1, wherein the second chamber is configured
to move relative to a position of the substrate.
7. The system of claim 1, wherein the second chamber is fluidly
coupled to a gas supply system.
8. The system of claim 7, wherein the gas supply system comprises
at least one reactant gas source, and a vacuum source.
9. The system of claim 1, wherein the first chamber is coupled to a
vacuum source.
10. A chemical-vapor deposition system comprising: first means for
confining one or more gases; second means for confining one or more
gases, the second means at least partly contained within the first
means; and third means for confining one or more gases, the third
means at least partly contained within the first means.
11. The system of claim 10, wherein the first means comprises a
right cylindrical chamber.
12. The system of claim 10, wherein the third means comprises a
surface of a substrate-support structure.
13. The system of claim 10, wherein the third means comprises one
or more heating elements operable to heat a substrate positioned on
the substrate-support structure, and one or more temperature
sensors operable to monitor a temperature of the substrate.
14. The system of claim 10, wherein the second means is separated
from the third means by a gas distribution surface.
15. The system of claim 12, wherein the third means comprises a
surface projection member that cooperatively interacts with the
substrate-support structure to form a gas confinement volume.
16. The system of claim 15, wherein the surface projection member
is configured to move relative to the substrate support
structure.
17. The system of claim 10, wherein the first means is fluidly
coupled to a gas supply system.
18. The system of claim 17, wherein the gas supply system comprises
at least one reactant gas source, and a vacuum source.
19. The system of claim 10, wherein the first means is coupled to a
vacuum source.
20. A chemical-vapor deposition system comprising: a first chamber
for confining gases; a second chamber within the first chamber
configured to at least partially contain a substrate during
deposition, the second chamber further comprising: a first plate
including one or more channels configured to communicate a gas
flow; and a second plate including two or more holes configured to
communicate a gas flow, wherein the first and second plates are
aligned to provide a continuous gas flow path from one of the
channels to the holes.
21. The system of claim 20, wherein at least one of the first plate
and the second plate comprises silicon.
22. The system of claim 21 wherein the first plate and the second
plate are photo lithographically patterned and etched to form the
one or more channels and the two or more holes.
23. The system of claim 20, wherein the first plate includes a
plurality of channels orthogonally configured in the first
plate.
24. The system of claim 20, wherein the second plate comprises a
hole arrangement in the second plate.
25. The system of claim 24, wherein the hole arrangement includes
one of a random arrangement of holes, a rectangular arrangement of
holes, and a concentric arrangement of holes.
26. The system of claim 20, wherein the second plate includes holes
that range in diameter from approximately 15 microns to
approximately 20 microns.
27. The system of claim 20, wherein first plate includes channels
that range in width from approximately 20 microns to approximately
45 microns.
28. The system of claim 20, wherein the first plate and the second
plate are fixedly aligned by bonding the first plate and the second
plate.
29. The system of claim 28, wherein bonding the first plate and the
second plate comprises passivating the bonded structure using a
thermal oxidation method.
30. The system of claim 20, wherein the first plate comprises a gas
inlet configured to fluidly communicate with the one or more
channels.
31. The system of claim 30, further comprising a gas supply system
configured to fluidly communicate with the gas inlet.
32. A chemical-vapor deposition system comprising: a first chamber
for confining gases; a second chamber within the first chamber to
at least partially contain a substrate during a deposition process,
the second chamber further comprising: a first plate including at
least one channel on a surface of the first plate and a gas inlet
on an opposing surface that is configured to fluidly communicate
with the at least one channel; and a second plate including at
least one aperture that extends through the second plate.
33. The system of claim 32, wherein the first plate and the second
plate sealably joined to provide a continuous flow passage that
extends from the aperture to the gas inlet.
34. The system of claim 32, wherein at least one of the first plate
and the second plate comprises a silicon substrate.
35. The system of claim 32, wherein the first plate and the second
plate are photo lithographically patterned and etched to form the
at least one channel and the at least one aperture.
36. The system of claim 32, wherein the first plate includes a
plurality of channels, wherein the plurality of channels are
orthogonally positioned in the first plate.
37. The system of claim 32, wherein the second plate includes a
plurality of apertures, wherein the plurality of apertures
comprises an aperture pattern in the second plate.
38. The system of claim 37, wherein the aperture pattern includes
one of a random pattern of apertures, a rectangular pattern of
apertures, and a concentric pattern of apertures.
39. The system of claim 32, wherein the second plate includes
apertures that range in size from approximately 15 microns to
approximately 20 microns.
40. The system of claim 32, wherein first plate includes channels
that range in width from approximately 20 microns to approximately
45 microns.
41. A chemical-vapor deposition system comprising: a first chamber
for confining gases; a second chamber within the first chamber
configured to at least partially contain a substrate during a
deposition process, the second chamber further comprising: a first
plate including a plurality of channels on a surface, and a gas
inlet on an opposing surface of the first plate that is configured
to fluidly communicate with the plurality of channels; a second
plate including a plurality of apertures that extend through the
second plate, the first plate and the second plate being sealably
joined to provide a continuous flow passage that extends from the
apertures to the gas inlet.
42. The system of claim 41, wherein the plurality of channels
comprise channels having a common width that ranges between
approximately 20 microns and approximately 45 microns.
43. The system of claim 41, wherein the plurality of apertures
comprise apertures having a common diameter that ranges between
approximately 15 microns and approximately 20 microns.
44. The system of claim 41, wherein the plurality of apertures
comprise a random arrangement of the apertures in the second
plate.
45. The system of claim 41, wherein the plurality of apertures
comprise a circular arrangement of the apertures in the second
plate.
46. The system of claim 41, wherein the plurality of apertures
comprise a rectangular arrangement of the apertures in the second
plate.
47. The system of claim 41, wherein the plurality of channels
comprise an orthogonal arrangement of the channels.
48. The system of claim 41, wherein the plurality of channels
comprise a concentric circular arrangement of the channels.
49. The system of claim 41, wherein the first plate and the second
plate are sealably joined by bonding the first plate and the second
plate using a silicon wafer bonding method to form a bonded
structure.
50. The system of claim 49, wherein the bonded structure comprises
a passivated and bonded structure.
Description
[0001] This application is a Divisional of U.S. application Ser.
No. 10/931,845, filed Aug. 31, 2004, which is a Divisional of U.S.
application Ser. No. 09/797,324, filed Mar. 1, 2001, now U.S. Pat.
No. 6,852,167, both of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] This invention concerns methods of making integrated
circuits, particularly layer-formation, such as chemical-vapor
deposition.
BACKGROUND OF THE INVENTION
[0003] Integrated circuits, the key components in thousands of
electronic and computer products, are interconnected networks of
electrical components fabricated on a common foundation, or
substrate. Fabricators generally build these circuits layer by
layer, using techniques, such as deposition, doping, masking, and
etching, to form thousands and even millions of microscopic
resistors, transistors, and other electrical components on a
silicon substrate, known as a wafer. The components are then wired,
or interconnected, together to define a specific electric circuit,
such as a computer memory.
[0004] One common technique for forming layers in an integrated
circuit is called chemical vapor deposition. Chemical vapor
deposition generally entails placing a substrate in a reaction
chamber, heating the substrate to prescribed temperatures, and
introducing one or more gases, known as precursor gases, into the
chamber to begin a deposition cycle. The precursor gases enter the
chamber through a gas-distribution fixture, such as a gas ring or a
showerhead, one or more centimeters above the substrate, and
descend toward the heated substrate. The gases react with each
other and/or the heated substrate, blanketing its surface with a
layer of material. An exhaust system then pumps gaseous by-products
or leftovers from the reaction out of the chamber through a
separate outlet to complete the deposition cycle.
[0005] Conventional chemical-vapor-deposition (CVD) systems suffer
from at least two problems. First, conventional CVD systems
generally form layers that include microscopic hills and valleys
and thus have non-uniform thickness. In the past, fabricators have
been able to overcome these hills and valleys through use of
post-deposition planarization or other compensation techniques.
However, escalating demands for greater circuit density, for
thinner layers, and for larger substrates make it increasingly
difficult, if not completely impractical, to overcome the
non-uniform thickness of conventional CVD layers.
[0006] Second, some conventional CVD systems are also inefficient
and time consuming. One significant factor affecting both CVD
efficiency and duration is the size of conventional reaction
chambers, which are generally made large to allow a loading
mechanism to insert and extract the substrate. Large chambers
generally require more gases to be introduced to achieve desired
gas concentrations. However, much of this gas is not only
unnecessary based on the amount of material deposited, but is
typically treated as waste. Moreover, large chambers also take
longer to fill up or pump out, prolonging deposition cycles and
thus slowing fabrication of integrated circuits.
[0007] Accordingly, there is a need for better systems and methods
of chemical-vapor deposition.
BRIEF DESCRIPTION OF THE DRAWING
[0008] FIG. 1 is a side view of an exemplary deposition reactor
according to the invention;
[0009] FIG. 2 is a top view of an exemplary gas-distribution
fixture according to the invention;
[0010] FIG. 3 is a flowchart showing an exemplary method according
to the invention; and
[0011] FIG. 4 is a diagram of an exemplary deposition system 400
incorporating a set of four deposition stations similar in
structure and function to system 100 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0012] The following detailed description, which references and
incorporates FIGS. 1-4, describes and illustrates specific
embodiments of the invention. These embodiments, offered not to
limit but only to exemplify and teach the invention, are shown and
described in sufficient detail to enable those skilled in the art
to make and use the invention. Thus, where appropriate to avoid
obscuring the invention, the description may omit certain
information known to those of skill in the art.
[0013] FIG. 1 shows an exemplary chemical-vapor-deposition system
100 which incorporates teachings of the present invention. In
particular, system 100 includes a chamber 110, a wafer holder 120,
a gas-distribution fixture 130, a gas supply system 140, and
exhaust pump 150, and a exhaust pump 160.
[0014] More particularly, chamber 110 includes respective top and
bottom plates 112 and 114 and a sidewall 116. In the exemplary
embodiment, chamber 110 is a cylindrical structure formed of
stainless steel or glass. However, other embodiments use different
structures and materials. Bottom plate 114 includes an opening
114.1. Extending through opening 114.1 is a stem portion 122 of
wafer holder 120.
[0015] Wafer holder 120 also includes a support platform 124, one
or more heating elements 126, and one or more temperature sensors
128. Support platform 124 supports one or more substrates, wafers,
or integrated-circuit assemblies 200. Substrate 200 has an
exemplary width or diameter of about 30 centimeters and an
exemplary thickness in the range of 850-1000 microns. (The term
"substrate," as used herein, encompasses a semiconductor wafer as
well as structures having one or more insulative, conductive, or
semiconductive layers and materials. Thus, for example, the term
embraces silicon-on-insulator, silicon-on-sapphire, and other
advanced structures.) Heating elements 126 and temperature sensors
128 are used for heating substrates 200 to a desired temperature.
Holder 120 is coupled to a power supply and temperature control
circuitry (both of which are not shown.) In the exemplary
embodiment, wafer holder 120 is rotatable either manually or
automatically and raises via manual or automatic lever mechanism
(not shown). Above wafer holder 120 and substrate 200 is
gas-distribution fixture 130.
[0016] Fixture 130 includes a gas-distribution member 132, a
surface-projection (or gas-confinement) member 134, and a gas inlet
136. Gas inlet 132 couples to gas-supply, gas-distribution channels
134, and a gas inlet 136. In the exemplary embodiment, fixture 130
has two operating positions 138.1 and 138.2 relative support
platform 124. Fixture 130 takes operating position 138.1, before
and after depositions and operating position 138.2 during
depositions.
[0017] Gas-distribution member 132 includes gas-distribution holes,
or orifices, 132.1 and gas-distribution channels 132.2. Holes 132.1
define a gas-distribution surface 132.3. In the exemplary
embodiment, holes 132.1 are substantially circular with a common
diameter in the range of 15-20 microns; gas-distribution channels
132.2 have a common width in the range of 20-45 microns; and
surface 132.3 is substantially planar and parallel to support
platform 124 of wafer holder 120. However, other embodiments use
other surface forms as well as shapes and sizes of holes and
channels. The distribution and size of holes may also affect
deposition thickness and thus might be used to assist thickness
control. Holes 132.1 are coupled through gas-distribution channels
132.2 to gas inlet 136.
[0018] Surface-projection member 134 projects or extends from
surface 132.3 toward support platform 124, defining a fixture
cavity 134.1. The exemplary embodiment forms surface-projection
member 134 from stainless steel as a uniform annular or circular
wall or collar that projects perpendicularly from surface 132 to
define a right-cylindrical cavity. However, other embodiments form
member 134 to project at other angles relative surface 132.3. For
example, some form the projection at an acute or obtuse angle, such
as 45 or 135 degrees, and others form the projection to
peripherally define an oval, ellipse, triangle, square, or any
desirable regular or irregular polygon. Thus, the present invention
encompasses a wide variety of projection shapes and configurations,
indeed any projection shape that facilitates definition of an
effective cavity or gas-confinement volume in cooperation with
wafer holder 120 and/or substrate 200.
[0019] FIG. 2, a plan view, shows further details of the exemplary
embodiment of gas-distribution fixture 130. In particular, the plan
view shows not only exemplary circular peripheries of
gas-distribution member 132 and surface-projection member 134, but
also an exemplary distribution pattern for holes 132.1 and an
exemplary orthogonal arrangement of gas-distribution channels
132.2. Other embodiments, however, use other hole distribution
patterns and channel arrangements. For example, some embodiments
include random or concentric hole patterns and various channel
geometries, including concentric circles, rectangles, or other
regular or irregular concentric polygons. Some embodiments may also
dedicate various subsets of channels and corresponding holes to
different gases.
[0020] Gas-distribution member 132 can be made in a number of ways.
One exemplary method entails providing two wafers of materials,
such as silicon or other passivatable, inert, or non-reactive
material. One wafer is patterned and etched, for example, using
conventional photolithographic or micro-electro-mechanical systems
(MEMS) technology, to form a pattern holes, and the other wafer is
patterned and etched to include a complementary or corresponding
pattern of gas-distribution channels. (MEMS refers to the
technologies of making structures and devices with micrometer
dimensions.) Dry-etching techniques produce small openings and
channels, while wet etching produces larger openings and channels.
For further details, see, for example, M. Engelhardt, "Modern
Application of Plasma Etching and Patterning in Silicon Process
Technology, " Contrib. Plasma Physics, vol. 39, no. 5, pp.
473-478(1999).
[0021] The two wafers are then bonded together with the holes and
channels in appropriate alignment using known wafer-bonding
techniques. See, for example, G. Krauter et al., "Room Temperature
Silicon Wafer Bonding with Ultra-Thin Polymer Films, " Advanced
Materials, vol. 9, no. 5, pp. 417-420(1997); C.E. Hunt et al.,
"Direct Bonding of Micromachined Silicon Wafers for Laser Diode
Heat Exchanger Applications, " J. Micromech. Microeng, vol. 1, pp.
152-156(1991); Zucker, O. et al., "Applications of oxygen plasma
processing to silicon direct bonding, " Sensors and Actuators, A.
Physical, vol. 36, no. 3, pp. 227-231(1993), which are all
incorporated herein by reference. See also, copending and
co-assigned U.S. patent application Ser. No. 09/189,276(dockets
303.534US1 and 97-1468) entitled "Low Temperature Silicon Wafer
Bond Process with Bulk Material Bond Strength, " which was filed
Nov. 10, 1998 and which is also incorporated herein by reference.
The resulting bonded structure is then passivated using thermal
oxidation for example.
[0022] For an alternative fixture structure and manufacturing
method that can be combined with those of the exemplary embodiment,
see U.S. Pat. No. 5,595,606, entitled "Shower Head and Film Forming
Apparatus Using Same, which is incorporated herein by reference. In
particular, one embodiment based on this patent adds a projection
or gas-confinement member to the reported showerhead structure.
[0023] FIG. 1 also shows that gas inlet 136 couples
gas-distribution fixture 130 to gas-supply system 140. Gas-supply
system 140 includes a gas line 142, gas sources 144 and 145, and
mass-flow controllers 146 and 147. Gas line or conduit 142, which
includes a flexible portion 142.1, passes through an opening 116.1
in chamber sidewall 116 to connect with gas inlet 136. Gas source
144 is coupled via mass-flow controller 146 to gas line 142, and
gas source 147 is coupled via mass-flow controller 147 to gas line
142. The exemplary embodiment provides computer-controlled thermal
or pressure-based mass-flow controllers; however, the invention is
not limited to any particular number or type of mass-flow
controller, nor to any particular number or set of gas sources.
[0024] System 100 also includes vacuum pumps 150 and 160. Vacuum
pump 150 is coupled to gas-distribution fixture 130 via a mass-flow
controller 152 and gas line 142. And, vacuum pump 160 is coupled to
the interior of chamber 110 via a line 162 and an opening 114.2 in
chamber bottom plate 114. In the exemplary embodiment, vacuum pump
160 has a greater capacity than vacuum pump 150.
[0025] In general operation, system 100 functions, via manual or
automatic control, to move gas-distribution fixture 130 from
operating position 138.1 to position 138.2, to introduce reactant
gases through fixture 130 onto substrate 200, and to deposit
desired matter through chemical-vapor deposition onto the
substrate. After the desired matter is deposited, pump 150
evacuates gases through fixture 130.
[0026] More particularly, FIG. 3 shows a flowchart 300 which
illustrates an exemplary method of operating system 100. Flowchart
300 includes process blocks 202-216.
[0027] The exemplary method begins at block 302 with insertion of
substrate 300 onto wafer holder 120. Execution then proceeds to
block 304.
[0028] Block 304 establishes desired temperature and pressure
conditions within chamber 110. In the exemplary embodiment, this
entails operating heating element 126 to heat substrate 200 to a
desired temperature, and operating vacuum pump 160 to establish a
desired pressure. Temperature and pressure are selected based on a
number of factors, including composition of the substrate and
reactant gases, as well as the desired reaction. After establishing
these deposition conditions, execution continues at block 306.
[0029] In block 306, the system forms or closes an inner chamber
around substrate 200, or more precisely a portion of substrate 200
targeted for deposition. In the exemplary embodiment, this entails
using a lever or other actuation mechanism (not shown) to move
gas-distribution fixture 130 from position 138.1 to position 138.2
or to move wafer holder 120 from position 138.2 to 138.1. In either
case, this movement places gas-distribution surface 132.3
one-to-five millimeters from an upper most surface of substrate
200. In this exemplary position, a lower-most surface of
surface-projection member 134 contacts the upper surface of support
platform 124, with the inner chamber bounded by gas-distribution
surface 132.3, surface-projection member 134, and the upper surface
of support platform 124.
[0030] Other embodiments define in the inner chamber in other ways.
For example, some embodiments include a surface-projection member
on support platform 124 of wafer holder 120 to define a cavity
analogous in structure and/or function to cavity 134.1. In these
embodiments, the surface-projection member takes the form of a
vertical or slanted or curved wall, that extends from support
platform 124 and completely around substrate 200, and the
gas-distribution fixture omits a surface-projection member.
However, some embodiments include one or more surface-projection
members on the gas-distribution fixture and the on the support
platform, with the projection members on the fixture mating,
engaging, or otherwise cooperating with those on the support
platform to define a substantially or effectively closed chamber.
In other words, the inner chamber need not be completely closed,
but only sufficiently closed to facilitate a desired
deposition.
[0031] After forming the inner chamber, the exemplary method
continues at block 308. Block 308 entails introducing one or more
reactant or precursor gases into the separate chamber. To this end,
the exemplary embodiment operates one or more mass-flow
controllers, such as controllers 146 and 147, to transfer gases in
controlled quantities and temporal sequences from gas sources, such
as sources 144 and 147, through gas line 142 and fixture 130 into
the separate chamber.
[0032] Notably, the inner chamber is smaller in volume than chamber
100 and thus requires less gas and less fill time to achieve
desired chemical concentrations (assuming all other factors equal.)
More precisely, the exemplary embodiment provides an inner chamber
with an empty volume in the range of 70 to 350 cubic centimeters,
based on a 1-to-5 millimeter inner-chamber height and a fixture
with a 30-centimeter diameter. Additionally, the number and
arrangement of holes in the fixture as well as the placement of the
holes close to the substrate, for example within five millimeters
of the substrate, promote normal gas incidence and uniform
distribution of gases over the targeted portion of substrate
200.
[0033] Block 310 entails allowing the gases to react with each
other and/or the heated substrate to deposit a layer of material on
targeted portions of the substrate. It is expected that the
resulting layer will exhibit a highly uniform thickness across the
entire substrate because of the more uniform gas distribution.
[0034] Next, as block 312 shows, the exemplary method entails
evacuating gaseous waste or by-products produced during the
deposition. To this end, the exemplary embodiment, activates vacuum
pump 160 to pump gaseous waste from the inner chamber through
gas-distribution fixture 130. In some embodiments, pumps 150 and
160 are operated concurrently to establish initial pressure
conditions and to evacuate the inner and outer chambers after
deposition.
[0035] In block 314, the system opens the separate chamber. In the
exemplary embodiment, this entails automatically or manually moving
gas-distribution fixture 130 to position 138.1. Other embodiments,
however, move the wafer holder or both the fixture and the wafer
holder. Still other embodiments may use multipart collar or
gas-confinement members which are moved laterally relative the
wafer holder or gas-distribution fixture to open and close an inner
chamber.
[0036] In block 316, substrate 200 is unloaded from chamber 110.
Some embodiments remove the substrate manually, and others remove
it using an automated wafer transport system.
[0037] FIG. 4 shows a conceptual representation of another
exemplary chemical-vapor-deposition system 400 incorporating
teachings of the present invention. System 400 includes a
rectangular outer chamber 410 which encloses four deposition
stations 420, 422, 424, and 426, loaded with respective substrates
200, 202, 204, and 206. Although the figure omits numerous
components for clarity, each deposition station is structurally and
operationally analogous to system 100 in FIG. 1. In the exemplary
embodiment, two or more of the stations are operated in parallel.
Additionally, other embodiments of this multi-station system
arrange the stations in a cross formation, with each station
confronting a respective lateral face of the chamber. Still other
embodiments use different outer chamber geometries, for example
cylindrical or spherical.
Conclusion
[0038] In furtherance of the art, the inventor has presented new
systems, methods, and apparatuses for chemical-vapor deposition.
One exemplary system includes an outer chamber, a substrate holder,
and a unique gas-distribution fixture. The fixture includes a
gas-distribution surface having holes for dispensing a gas and a
gas-confinement member that engages, or otherwise cooperates with
the substrate holder to form an inner chamber within the outer
chamber.
[0039] Notably, the inner chamber not only consumes less gas during
deposition to reduce deposition waste and cost, but also
facilitates rapid filling and evacuation to reduce deposition cycle
times (with all other factors being equal.) The inner chamber also
places the gas-distribution fixture within several millimeters of a
substrate on the substrate holder, promoting normal gas incidence
across the chamber and thus uniform deposition thickness.
[0040] To address these and other problems, the present inventor
devised new systems, methods, and apparatuses for chemical-vapor
deposition. One exemplary chemical-vapor deposition system includes
an outer chamber, a substrate holder, and a unique gas-distribution
fixture. The fixture includes a gas-distribution surface having
holes for dispensing a gas and a gas-confinement member that forms
a wall around the holes. In operation, the gas-confinement member
engages, or otherwise cooperates with the substrate holder to form
an inner chamber within the outer chamber.
[0041] The inner chamber has a smaller volume than the outer
chamber and thus consumes less gas during the deposition process
than would the outer chamber used alone. Also, the smaller chamber
volume allows the exhaust system to pump the chamber more quickly,
thus increasing the rate of the CVD process. In addition, the
exemplary showerhead is made of a material, like silicon, which can
be easily passivated to reduce reaction with reactive gases, thus
reducing chemical-vapor buildup in the showerhead. Also, the
exemplary showerhead includes a configuration of holes that permits
uniform gas flow.
[0042] The embodiments described above are intended only to
illustrate and teach one or more ways of practicing or implementing
the present invention, not to restrict its breadth or scope. The
actual scope of the invention, which embraces all ways of
practicing or implementing the invention, is defined only by the
following claims and their equivalents.
* * * * *