U.S. patent application number 10/214272 was filed with the patent office on 2002-12-26 for vortex based cvd reactor.
Invention is credited to Brubaker, Matthew D., Grant, Robert W., Mumbauer, Paul D., Petrone, Benjamin J..
Application Number | 20020195055 10/214272 |
Document ID | / |
Family ID | 24764876 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020195055 |
Kind Code |
A1 |
Grant, Robert W. ; et
al. |
December 26, 2002 |
Vortex based CVD reactor
Abstract
Chemical vapor deposition reactor incorporating gas flow vortex
formation for uniform chemical vapor deposition upon a stationary
wafer substrate. Gas flow including chemical vapors is introduced
in tangential fashion to the interior of the heated reactor to
provide for suitable uniform boundary layer control within the
reactor upon the stationary wafer substrate.
Inventors: |
Grant, Robert W.; (Camden,
ME) ; Petrone, Benjamin J.; (Mt. Bethel, PA) ;
Brubaker, Matthew D.; (Colorado Springs, CO) ;
Mumbauer, Paul D.; (Coopersburg, PA) |
Correspondence
Address: |
PATTON BOGGS
PO BOX 270930
LOUISVILLE
CO
80027
US
|
Family ID: |
24764876 |
Appl. No.: |
10/214272 |
Filed: |
August 6, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10214272 |
Aug 6, 2002 |
|
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09688555 |
Oct 16, 2000 |
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6428847 |
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Current U.S.
Class: |
118/715 |
Current CPC
Class: |
C23C 16/45563 20130101;
C23C 16/455 20130101; C23C 16/45502 20130101; C30B 25/14
20130101 |
Class at
Publication: |
118/715 |
International
Class: |
C23C 016/00 |
Claims
It is claimed:
1. A vortex based CVD reactor comprising: a. a reactor base; b. a
reactor sidewall located above and secured to the reactor base; c.
a top located above, and secured and fitted to the reactor
sidewall; d. injector tubes tangentially oriented and secured to a
reactor top; e. a reactor interior comprised of inner surfaces of
the reactor base, reactor side walls and a reactor top; f. a heated
densified carbon susceptor located in contact with a resistance
heated chuck; g. at least one lift yoke and ceramic wafer substrate
support pin; h. a robotic access port located in the reactor base,
a positionable shutter aligned with the robotic access port; and,
i. an exhaust port located at the upper region of the reactor
top:
2. The reactor of claim 1, including tangentially oriented injector
tubes for introducing chemical vapors into the reactor in
tangential fashion, thereby creating spinning gas fields which
cause a uniform boundary layer to form over the substrate whereby
the chemical vapors deposit uniformly.
3. A vortex based CVD reactor with a spinning gas field within the
reactor interior, comprising the steps of: a. introducing chemical
vapors into a reactor interior simultaneously under sufficient
pressure and at suitable temperature through injector tubes; b.
chemical vapors emanating from injector tubes and producing
spinning gas fields; c. orienting injector tubes to direct the
spinning gas fields . containing chemical vapors tangentially with
respect to the interior walls of the reactor sidewall; d. rotating
gas field moves downward due to the reduced diameter of the
reactor; e downward spiraling gas hits the lower surface and
substrate and is subject to drag, loss of velocity from drag causes
the gas to flow inward and upward to where the pressure is lower;
and, f. the gas spirals upward and out of a reactor exhaust.
Description
CROSS REFERENCES TO CO-PENDING APPLICATIONS
[0001] None.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is for a chemical vapor deposition
reactor, and, more specifically, is for a chemical vapor deposition
reactor incorporating gas flow vortex mixing action for uniform
chemical vapor deposition upon a stationary wafer substrate. Gas
flow including chemical vapors is introduced in tangential fashion
to the interior of the heated reactor to provide for suitable
uniform rotation of the gas field within the reactor and create a
uniform boundary layer over the stationary wafer substrate.
[0004] 2. Description of the Prior Art
[0005] Prior art reactors used for chemical vapor deposition on a
water substrate often incorporated rotating heated chucks which
held the wafer substrate which was rotated into the path of
oncoming chemical vapor emanating from a multiple orifice injector
device often referred to as functioning similarly to a shower head.
Proximity of the heated rotating chuck to the multiple orifice
injector device caused undesired heating of the multiple orifice
injector device to cause the chemical vapor to decompose at high
temperatures As a, result, chemical vapor was turned into
particulate matter which clung to and which was deposited in the
multiple orifices, thereby causing clogging of the orifices to
cause flow restriction and improper chemical vapor deposition on
the wafer substrate. Such clogging required shutting down of the
process so that the orifices could be cleaned- Also, because of
poor temperature regulation, the chemical vapor would decompose and
would be deposited on the sidewalls of the reactor, thereby causing
inefficient operation which also required shutdown for cleaning
purposes. Rotating heated chucks also required elaborate vacuum
pumping schemes, and a way to transfer heat to the rotating heated
chuck. The use of pyrometry and associated circuitry was also
required to sense and control chuck temperature. Clearly what is
needed is a CVD reactor which overcomes the problems found in prior
art devices.
SUMMARY OF THE INVENTION
[0006] The general purpose of the present invention is to provide a
reactor for deposition of chemical vapor onto a substrate wherein
chemical vapors introduced into the reactor will disperse uniformly
onto the substrate without the need for rotating or otherwise
moving the substrate.
[0007] According to the present invention, the above stated general
purpose is achieved by a vortex based CVD reactor including a
reactor base, a reactor sidewall located above and secured to the
reactor base, a top located above and secured and fitted to the
reactor sidewall, injector tubes tangentially oriented and secured
to the reactor top, a reactor interior comprised of the inner
surfaces of the reactor base, reactor side walls and reactor top, a
heated densified carbon susceptor located in intimate contact with
a resistance heated chuck, a lift yoke and ceramic wafer substrate
support pins, a robotic access port located in the reactor base, a
positionable shutter aligned with the robotic access port, and an
exhaust port located at the upper region of the reactor top. The
tangentially oriented injector tubes serve to introduce chemical
vapors into the reactor in tangential fashion, thereby creating
spinning gas fields which cause a uniform boundary layer to form
over the substrate whereby the chemical vapors deposit
uniformly.
[0008] The reactive gas is introduced at or above its boiling
point, and is caused to react at the substrate that is held at its
higher, decomposition temperature.
[0009] One significant aspect and feature of the present invention
is a CVD reactor which incorporates a vortex gas flow for the
uniform deposition of chemical vapors upon a water substrate.
[0010] Another significant aspect and feature of the present
invention is the use of tangentially located injector tubes at the
reactor top for the introduction of chemical vapors to the reactor
interior in tangential fashion.
[0011] Still another significant aspect and feature of the present
invention is the chemical vapor deposition upon a wafer substrate
which is stationary.
[0012] Yet another significant aspect and feature of the present
invention is a CVD reactor having a minimum of moving parts.
[0013] A further significant aspect and feature of the present
invention is a CVD reactor which eliminates or minimizes the
deposit of particulates on the reactor components.
[0014] A further significant aspect and feature of the present
invention is a CVD reactor having a positionable shutter to provide
a non-interrupted reactor interior.
[0015] Having thus described an embodiment of the present invention
and set forth significant aspects and features thereof, it is the
principal object of the present invention to provide a vortex based
CVD reactor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] other objects of the present invention and many of the
attendant advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings, in which like reference numerals
designate like parts throughout the figures thereof and
wherein:
[0017] FIG. 1 illustrates an isometric view of a vortex based CVD
reactor, the present invention;
[0018] FIG. 2 illustrates a cross section view of the vortex based
CVD reactor along line 2-2 of FIG. 1;
[0019] FIG. 3 illustrates a top view of the reactor base;
[0020] FIG. 4 illustrates an isometric view of the reactor
base;
[0021] FIG. 5 illustrates a cross section view of the vortex based
CVD reactor showing a spinning gas field within the reactor
interior;
[0022] FIG. 6 illustrates a top view of the vortex based CVD
reactor showing the spinning gas field in the reactor interior;
[0023] FIG. 7 illustrates the flow of gas as simulated by using the
exact dimensions, gas type, and temperature; and,
[0024] FIG. 8 illustrates a top view of the rotating gas field at
the plane of the substrate, showing good homogeneity of the
spiraling gas.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] FIG. 1 illustrates an isometric view of a vortex based CVD
(chemical vapor deposition) reactor, also referred to as the CVD
reactor 10. Components illustrated in FIG. 1 include a circular
reactor base 12, a circular sidewall 14 located above and fitted to
and secured to the reactor base 12 by a plurality of clamps
16a-16n, a circular reactor top 18 located above and fitted to and
secured to the reactor sidewall 14 by a plurality of hardware
assemblies 20a-20n, a plurality of injector tubes 22a-22n
tangentially secured to and extending through the reactor top 18
and communicating with the reactor interior 24 (FIG. 2), an exhaust
port 26 centrally located at the reactor top 18 in communication
with the reactor interior 24, a rectangular reactor base extension
28 extending outwardly from the reactor base 12 having a flange 30,
and, a robotic arm access port 32 located central to the
rectangular reactor base extension 28 in communication with the
reactor interior 24.
[0026] FIG. 2 illustrates a cross section view of the vortex based
CVD reactor 10 along line 2-2 of FIG. 1, where all numerals
mentioned previously correspond to those elements previously
described. Illustrated in particular are the components located in
or adjacent to a cavity 34 located in the reactor base 12. The
cavity 34 houses a variety of components, most of which are also
shown in FIGS. 3 and 4, as now described. An attachment ring 36
seals against the lower planar region 38 of the reactor base 12 by
the use of an 0-ring 40 and a plurality of machine screws 42a-42n.
A connecting support collar 44 extends vertically through the lower
planar region 38 of the reactor base 12 and through the attachment
ring 36 to support a resistance heated chuck 46. A removable
densified carbon susceptor 48 aligns in intimate contact with the
resistance heated chuck 46 and uniformly transfers heat to a wafer
substrate 50 which intimately contacts the densified carbon
susceptor 48. A lift yoke 52 which is actuated vertically by an air
cylinder lift arm 54 aligns with sufficient clearance about the
connecting support collar 44. A plurality of upwardly directed
ceramic lift pins 5Sa-56n secure to the lift yoke 52 and extend
freely through a plurality of mutually aligned body holes 58a-58n
and 60a-60n in the heated chuck 46 and the densified carbon
susceptor 48, respectively. The tops of the ceramic lift pins
56a-56n can extend beyond the upper surface of the densified carbon
susceptor 48 when the lift yoke 52 is actuated to its uppermost
travel.
[0027] The ceramic lift pins 56a-56n support or position a wafer
substrate 50 vertically either to be processed or to be positioned
by robotic handling. The lift yoke 52 is shown in its lowermost
position whereby the wafer substrate 50 is allowed to intimately
contact the densified carbon susceptor 48 for processing. Also
attached to the lift yoke 52 is a positionable shutter 62, also
shown in FIGS. 3 and 4. The shutter 62 is shaped to conform with
the contour of the lower region of the reactor base 12 to assist in
providing a uniformly smooth shaped reactor interior 24. Multiply
angled brackets 64 and 66 suitably secure to the lift yoke 52 and
are located in channels 68 and 70 (FIG. 3) in the lower region of
the reactor base 12 to attach to and to provide for support for the
positionable shutter 62. Plates 72 and 74 secure over and about the
channels 68 and 70 to limit the upward movement of the multiply
angled brackets 64 and 66 and correspondingly to limit the upward
movement of the shutter 62 in the open mode. For robotic handling
the lift yoke 52 is positioned upwardly to position the ceramic
lift pins 56a-56n above the upper surface of the densified carbon
receptor 48, thereby moving the processed wafer substrate 50 to a
position shown in dashed lines and designated with reference
alphanumeric symbol 50a. Simultaneously, the shutter 62 is
positioned upwardly as shown by dashed lines and referenced by
alphanumeric symbol 62a to allow access to the reactor interior 24
by robotic means entering through the robotic arm access port 32.
For insertion of a wafer substrate, the lift yoke 52 including the
shutter 62 and ceramic lift pins 56a-56n is positioned to its full
upward position whereby robotic handling equipment deposits a wafer
substrate upon the extended ceramic lift pins 56a-56n. The lift
yoke 52 is then lowered to deposit the wafer substrate on the
densified carbon susceptor 48 and to close the shutter 62.
[0028] A thermocouple 76 is located in the heated chuck 46 to
sample and control temperature of the heated chuck 46 and the
densified carbon susceptor 48 during the deposition process. A
resistance heater 78 surrounds the reactor sidewall 14. Also shown
is flange 80 at the upper edge of the reactor base 12, which, with
an O-ring 82, seals against a lower flange 84 of the reactor
sidewall 14. An upper flange 86 along with an O-ring 88 seals
against a flange 9o located on the reactor top 18.
[0029] FIG. 3 illustrates a top view of the reactor base 12, where
all numerals correspond to those elements previously described.
Illustrated in particular is the relationship of the lift yoke 52
and the attached shutter 62 to the reactor base 12, as previously
described.
[0030] FIG. 4 illustrates an isometric view of the reactor base 12,
where all numerals correspond to those elements previously
described. The lift yoke 52 is shown positioned upwardly by the air
cylinder lift arm 54 to accept placement of a wafer substrate 50
such as by robotic handling equipment. Positioning of the lift yoke
52 upwardly also positions the attached shutter 62 by the multiply
angled brackets 64 and 66 (not shown) so that robotic equipment may
access the interior of the CVD reactor 10 through the robotic arm
access port 32 to place or retrieve a wafer substrate 50.
Mode of Operation
[0031] FIG. 5 illustrates a cross section view of the vortex based
CVD reactor 10 showing a spinning gas field 92 within the reactor
interior 24, where all numerals mentioned previously correspond to
those elements previously described, Chemical vapors are introduced
into the reactor interior 24 simultaneously under sufficient
pressure and at suitable temperature through the injector tubes
22a-22n. Chemical vapors 94 emanate from injector tubes 22a-22n and
produce spinning gas fields. For purposes of brevity and clarity,
only the spinning gas field 92 produced by and emanating from the
injector tube 22a is shown, it being understood that multiple
complementary spinning gas fields are produced by and emanate from
the remaining injector tubes 22b-22n in a similar fashion. The
injector tubes 22a-22n are oriented to direct the spinning gas
field(s) 92 containing chemical vapors 94 tangentially with respect
to the interior walls of the reactor sidewall 14. The rotating gas
field moves downward due to the reduced diameter of the reactor
(i.e., lower pressure area). The downward spiraling gas hits the
lower surface and substrate and is subject to drag. Loss of
velocity from drag causes the gas to flow inward and upward to
where the pressure is lower. Therefore, the gas spirals upward and
out of the reactor exhaust. Conservation of angular momentum
maintains continuity of spiral direction and low turbulence. See
FIG. 7 (side view) and FIG. 8 (top view at substrate plane).
[0032] FIG. 6 illustrates a top view of the vortex based CVD
reactor 10 where the reactor top 18 is not shown for purposes of
brevity and clarity, but the injector tubes 22a-22n are shown
poised above the reactor interior 24 of the CVD reactor 10. As in
FIG. 5, and for purposes of brevity and clarity, only the spinning
gas field 92 produced by and emanating from the one injector tube
22a is shown, it being understood that multiple complementary
spinning gas fields are produced by and emanate from the remaining
injector tubes 22b-22n in a similar fashion. All numerals
correspond to those elements previously described.
[0033] FIG. 7 illustrates an exact fluidic simulation of the
proposed vortex CVD reactor.
[0034] FIG. 8 illustrates a simulation showing gas motion at the
plane of the substrate where the gas is spiraling with little
turbulence.
[0035] A mathematical discussion from Schlicting-Boundary Layer
Theory by Schlicting for a rotating gas field upon a flat surface.
This is very similar to the proposed invention and shows the
development of a uniform boundary layer. This illustrates how the
boundary layer of gas is proportional to 1 v w v = viscosity w =
rotational velocity
[0036] The boundary layer in this instance is not dependent on
radius, etc. This is critical to uniform CVD growth reactions.
[0037] Various; modifications can be made to the present invention
without departing from the apparent scope hereof
* * * * *