U.S. patent application number 11/293346 was filed with the patent office on 2007-06-07 for high-throughput deposition system for oxide thin film growth by reactive coevaportation.
Invention is credited to Brian Moeckly, Ward Ruby, Kurt Von Dessonneck.
Application Number | 20070125303 11/293346 |
Document ID | / |
Family ID | 38117466 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070125303 |
Kind Code |
A1 |
Ruby; Ward ; et al. |
June 7, 2007 |
High-throughput deposition system for oxide thin film growth by
reactive coevaportation
Abstract
A heater for growing a thin film on substrates contained on a
substrate support member includes a plurality of heater elements.
The substrate support member containing the substrates is at least
partially surrounded by the plurality of heater elements. At least
two of the plurality of heater elements are moveable with respect
to one another so as to provide external access to the substrate
support member. An oxygen pocket is formed in one of the heater
elements or a separate oxygen pocket member and is used for
oxidation of the film on the substrates.
Inventors: |
Ruby; Ward; (Palm City,
FL) ; Von Dessonneck; Kurt; (Auburn, CA) ;
Moeckly; Brian; (Santa Barbara, CA) |
Correspondence
Address: |
Vista IP Law Group LLP
2040 MAIN STREET, 9TH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
38117466 |
Appl. No.: |
11/293346 |
Filed: |
December 2, 2005 |
Current U.S.
Class: |
118/724 ;
118/725; 118/726; 118/728 |
Current CPC
Class: |
C23C 14/546 20130101;
C23C 14/505 20130101; C23C 14/24 20130101; C23C 14/0021 20130101;
C23C 14/566 20130101; C23C 14/541 20130101 |
Class at
Publication: |
118/724 ;
118/726; 118/725; 118/728 |
International
Class: |
C23C 16/00 20060101
C23C016/00 |
Claims
1. A heater for growing a thin film on substrates contained on a
substrate support member comprising: a plurality of heater
elements, wherein the substrate support member containing the
substrates is at least partially surrounded by the plurality of
heater elements, and wherein at least two of the plurality of
heater elements are moveable with respect to one another so as to
provide external access to the substrate support member.
2. The heater of claim 1, wherein the heater comprises a top heater
element, a side heater element, and a bottom heater element.
3. The heater of claim 1, wherein one of the plurality of heater
elements is moveable with respect to a stationary heater
element.
4. The heater of claim 3, wherein the bottom heater includes a
window opening in a portion thereof.
5. The heater of claim 3, wherein the bottom heater element is
stationary and the top heater element and the side heater element
are movable with respect to the bottom heater element.
6. The heater of claim 3, wherein the top heater element and the
side heater element are stationary and the bottom heater element is
moveable with respect to the top and side heater elements.
7. The heater of claim 1, wherein at least two of the plurality of
heater elements are connected via a hinge.
8. The heater of claim 1, wherein the substrate support member is
supportable on a vertically oriented spindle.
9. The heater of claim 8, wherein the substrate support member is
gravitationally held on the spindle.
10. The heater of claim 1, wherein the spindle is rotatable.
11. The heater of claim 9, wherein the substrate support member is
moveable in a vertical direction.
12. A heater for growing a thin film on substrates comprising: a
heater cap comprising a top plate having a side wall about its
periphery, the top plate and side wall each having a heating
element disposed therein; a lower heater plate having an upper and
lower surface, a portion of the lower heater plate having a window
disposed therein passing from the upper surface to the lower
surface of the lower heater plate and a recessed pocket formed in a
portion of the upper surface of the lower heater plate; and wherein
the heater cap and lower heater plate are moveable with respect to
one another in a direction perpendicular to the upper face of the
lower heater plate.
13. The heater of claim 12, wherein the lower heater plate is
stationary and the heater cap is moveable with respect to the lower
heater plate.
14. The heater of claim 12, wherein the heater cap is stationary
and the lower heater plate is moveable with respect to the heater
cap.
15. The heater of claim 12, further comprising an actuator for
moving the heater cap with respect to the lower heater plate.
16. A heater for growing a thin film on substrates comprising: an
upper heater zone comprising a top member having a side wall about
its periphery, the top member and side wall each having a heating
element disposed therein; a lower heater zone having a heating
element disposed therein; an oxygen pocket member having an upper
and lower surface, a portion of the oxygen pocket member having a
window disposed therein passing from the upper surface to the lower
surface and a recessed pocket formed in a portion of the upper
surface of the oxygen pocket member, the oxygen pocket member at
least partially surrounded by at least one of the upper heater zone
and lower heater zone; and wherein the upper heater zone is
moveable in a direction perpendicular to the upper face of the
oxygen pocket member.
17. A method of unloading and loading a substrate support member in
a heater comprising the steps of: providing a heater having a
plurality of heater elements, wherein the substrate support member
is at least partially surrounded by the plurality of heater
elements, and wherein at least two of the plurality of heater
elements are moveable with respect to one another so as to provide
external access to the substrate support member; moving the
plurality of heater elements into an unload position; removing the
substrate support member from the heater; inserting a second
substrate support member into the heater; and moving the plurality
of heater elements into a loaded position.
18. The method of claim 17, wherein heater is disposed in a vacuum
chamber.
19. The method of claim 17, further comprising the step of
depositing a thin film on substrates disposed on the substrate
support member.
20. The method of claim 18, wherein the removal and insertion of
the substrate support members occurs under vacuum conditions.
21. The method of claim 17, wherein the at least two of the
plurality of heater elements are moveable with respect to one
another in a vertical direction.
22-43. (canceled)
Description
FIELD OF THE INVENTION
[0001] The field of the invention generally relates to devices and
methods used to produce thin films on a substrate. More
specifically, the field of the invention relates to devices and
methods used to form high-temperature superconducting (HTS) films
in-situ.
BACKGROUND OF THE INVENTION
[0002] Since the discovery in the mid 1980s of the perovskite
family of HTS materials, extensive strides have been made in the
ability to deposit high quality HTS films. Thin films formed from
HTS materials are highly desirable for a variety of superconductive
electronics applications including, for example, detectors, digital
circuits, and passive microwave devices (e.g., HTS-based
filters).
[0003] Over the years, several techniques have been developed for
the deposition of thin films of HTS oxide materials. These
techniques include sputtering, pulsed laser deposition (PLD), and
metal-organic chemical vapor deposition (MOCVD). Illustrative HTS
oxide materials include Yttrium Barium Copper Oxide (YBCO), Bismuth
Strontium Calcium Copper Oxide (BSCCO), Thallium Barium Calcium
Copper Oxide (TBCCO), and Mercury Barium Calcium Copper Oxide
(HBCCO). Of these materials, YBCO is currently the favored compound
for many applications due to YBCO's relatively smaller conduction
anisotropy, high superconductive critical current in a magnetic
field, and good chemical stability. In addition, as compared to the
other HTS compounds, the relative ease with which high quality,
single phase thin films of YBCO may be grown is perhaps its
greatest attribute.
[0004] Nonetheless, thin film growth of these materials has still
been difficult. In order to obtain high quality films, oriented,
epitaxial growth (in-plane and out-of-plane) is necessary, meaning
that the films can be grown only at high temperatures, typically
above 700.degree. C. Therefore, growth is only possible on a
handful of single crystal substrates that satisfy strict
requirements of chemical compatibility, lattice constant match, and
thermal expansion match. In addition, the properties of the
substrate must be suitable for the required application. For
example, MgO is a substrate that meets the growth needs and also
has sufficiently low loss for microwave applications.
[0005] Growth of HTS materials is further complicated by the fact
that these compounds typically comprise at least three metallic
species which are in oxide form. The growth methods employed must
therefore be strictly controlled in order to achieve the proper
film stoichiometry and uniformity. Furthermore, in-situ growth of
these materials requires them to be oxygenated as they are grown,
which is generally not compatible with many conventional techniques
such as physical vapor deposition. Moreover, in certain
applications, growth of HTS thin films on two sides of a single
substrate is required.
[0006] Conventional in-situ growth techniques such as sputtering,
pulsed laser deposition, and metal-organic chemical vapor
deposition have all been successfully used for the growth of HTS
thin films. There are, however, serious limitations to these
methods including slow growth rate (sputtering), difficulty in
controlling composition, poor reproducibility, poor film uniformity
(sputtering, MOCVD), difficulty of achieving large-area deposition
(PLD), and difficulty of scalability (all aforementioned
techniques).
[0007] More recently, the technique of reactive coevaporation using
a rotating oxygen-pocket heater has been used which addresses many
of the limitations discussed above. In this technique, the
substrates are held by gravity on a rotating substrate support
member or turntable. The substrate support member containing the
substrates is surrounded on the top, bottom, and sides by a
cylindrically-shaped heater (i.e., a heater body) that radiatively
heats the substrates to a uniform high temperature necessary for
reaction. The substrate support member is rotatable inside the
heater body and, during a portion of the rotation, is exposed to a
vacuum chamber via a window disposed in the underside portion of
the heater body. The vacuum chamber surrounds the heater body and
contains the deposition sources for the reaction.
[0008] In one embodiment, the heater body also includes an oxygen
pocket region located in the bottom portion of the heater body.
Oxygen is fed into the oxygen pocket region and thereby exposes the
substrates to oxygen during a portion of the rotation. A large
pressure differential is created between the oxygen pocket region
and the surrounding vacuum chamber. The pressure differential is
maintained by a narrow gap formed between the rotating substrate
support member and the oxygen pocket region, thereby resulting in a
low rate of oxygen leakage from the oxygen pocket.
[0009] During the part of the rotation where the substrates are
exposed to the vacuum chamber, the thin film constituents
(typically metallic species) may be deposited onto the underside of
the substrates using typical PVD techniques such as evaporation.
Oxidation reactions take place when the substrates are rotated on
the substrate support member into the oxygen pocket.
[0010] Reactive coevaporation using a rotating oxygen pocket heater
has several advantages including, for example, the ability to
evaporate the metallic species in vacuum without complications that
would arise under the high oxygen pressure conditions needed for
growth of HTS films. In addition, the rotating oxygen pocket heater
technique permits deposition on substrates having a relatively
large surface area. Moreover, this technique has the ability to
deposit HTS materials on multiple substrates at once. Because the
heater approximates a blackbody radiator, different substrate
materials can also be incorporated simultaneously even if they have
different absortivities. Finally, reactive coevaporation using the
rotating oxygen pocket heater allows one to deposit HTS materials
on both sides of the substrate sequentially because neither side of
the substrate is in direct contact with the heater body.
[0011] While reactive coevaporation methods are well suited for the
formation of HTS thin films, there remains a need to increase the
capacity and stability of such methods so that reactive
coevaporation can be implemented into a commercially viable
manufacturing process. There thus is a need to increase the
throughput and reliability of reactive coevaporation deposition
systems and methods.
SUMMARY OF THE INVENTION
[0012] In a first aspect of the invention, a device for performing
reactive coevaporation includes a heater chamber containing a
pocket heater, a source chamber containing a source holder, the
source chamber being coupled to the heater chamber through a valve,
and a transfer chamber containing an extendable transfer arm, the
transfer chamber being coupled to the heater chamber via a valve,
the extendable transfer arm being moveable into and out of the
heater chamber via the valve, wherein the heater chamber, source
chamber, and transfer chamber are coupled to a vacuum source. The
device may be used to form oxide thin films, including for example,
rare earth (RE) oxides such as (RE)BCO.
[0013] In another aspect of the invention, a device for performing
reactive coevaporation on at least one substrate having a front and
back surface includes a heater chamber containing a pocket heater,
a source chamber containing source holder, the source chamber being
coupled to the heater chamber via a valve, a substrate support
member for securing the at least one substrate, the substrate
support member securing the at least one substrate by contacting
one or both of the front and back surface of the at least one
substrate, and an extendable transfer arm for holding the substrate
support member, the extendable transfer arm being rotatable so as
to expose either or both of the front or back surface of the at
least one substrate toward the source chamber.
[0014] In still another aspect of the invention, a pocket heater
includes a heater cap or upper heater zone comprising a circular
top plate having a cylindrical side wall about its periphery, the
circular top plate and side wall having a heater element (e.g.,
heater wire) disposed therein, a lower heater plate having an upper
and lower surface, a portion of the lower heater plate having a
window disposed therein passing from the upper surface to the lower
surface of the lower heater plate and a recessed pocket formed in a
portion of the upper surface of the lower heater plate, and wherein
the heater cap is moveable in a direction that is perpendicular
with respect to a surface of the lower heater plate.
[0015] In another aspect of the invention, a device for performing
reactive coevaporation includes a pocket heater disposed in a
heater chamber, a loading transfer chamber containing an extendable
transfer arm, the loading transfer chamber being coupled to the
heater chamber containing the pocket heater by a valve, and an
unloading transfer chamber containing an extendable transfer arm,
the unloading transfer chamber being coupled to the heater chamber
containing the pocket heater by a valve.
[0016] In still another aspect of the invention, a method of
performing reactive coevaporation includes the steps of providing a
pocket heater disposed in a heater chamber, the pocket heater
including vertically moveable spindle passing through a portion of
the pocket heater, providing a loading transfer chamber containing
an extendable transfer arm, the loading transfer chamber being
coupled to the heater chamber containing the pocket heater by a
valve, and providing a source chamber containing source
material.
[0017] The substrate support member containing at least one
substrate is loaded onto the extendable transfer arm inside the
loading transfer chamber. Vacuum conditions are established inside
the loading transfer chamber using a vacuum pump coupled to the
loading transfer chamber. The valve between the heater chamber
containing the pocket heater and the loading transfer chamber is
then opened and the substrate support member containing at least
one substrate is extended into the pocket heater using the
extendable transfer arm. The spindle is raised so as to lift the
substrate support member containing at least one substrate off the
extendable transfer arm. The extendable transfer arm is retracted
into the loading transfer chamber, and the source material is
evaporated after the correct substrate temperature, pocket
pressure, and substrate support member rotation speed have been
established.
[0018] In still another aspect of the invention, a device includes
a heater cap or upper heater zone comprising a circular top having
a cylindrical side wall about its periphery, the circular top and
side wall having a heater element disposed therein, a lower heater
plate having an upper and lower surface, a portion of the lower
heater plate having a window disposed therein passing from the
upper surface to the lower surface of the lower heater plate and a
recessed pocket formed in a portion of the upper surface of the
lower heater plate, a z-adjust assembly.
[0019] In one aspect of the invention, the z-adjust assembly
includes a rotatable spindle projecting through a center hole in
the lower heater plate, a motor mechanically coupled to the
spindle, and a roller. The inclined cam engages with the roller,
wherein movement of the inclined cam in the horizontal direction
imparts movement of the rotatable spindle, motor, and roller in the
z-direction.
[0020] In still another aspect of the invention, a device for
performing reactive coevaporation includes a heater chamber
containing a pocket heater, a source chamber containing source
holder, the source chamber being coupled to the heater chamber via
a valve, a monitor chamber containing at least one deposition
monitor, the monitor chamber being coupled to the heater chamber
containing the pocket heater via a valve.
[0021] In yet another aspect of the invention, a device for
performing reactive coevaporation includes a heater chamber
containing a pocket heater, a source chamber containing
coevaporation source material, the source chamber being coupled to
the heater chamber via a valve.
[0022] In another embodiment of the invention, a method of loading
and unloading a substrate support member in a pocket heater
includes the steps of: (1) providing a pocket heater having a
heater cap (e.g., an upper heating zone) including a circular top
and a cylindrical side wall about its periphery; (2) providing a
lower heater plate (e.g., lower heating zone) having an upper and
lower surface, a portion of the lower heater plate having a window
disposed therein passing from the upper surface to the lower
surface of the lower heater plate and a recessed pocket formed in a
portion of the upper surface of the lower heater plate; (3)
providing a first rotatable substrate support member for holding a
plurality of substrates, the first rotatable substrate support
member being interposed between the lower heater plate and the
heater cap; (3) moving the heater cap into an unload position
disposed away from the first rotatable substrate support member in
a direction perpendicular to the upper surface of the lower heater
plate; (4) removing the first rotatable substrate support member
from the pocket heater; (5) inserting a second rotatable substrate
support member into the pocket heater, the second rotatable
substrate support member interposed between the heater cap and the
lower heater plate; and (6) moving the heater cap into a loaded
position disposed adjacent to the second rotatable substrate
support member.
[0023] It is an object of the invention to provide a device and
method that increases the throughput of multi-component HTS films
deposited/grown on substrates using reactive coevaporation. It is a
further object of the invention to separate various aspects of the
deposition process (e.g., source material evaporation, loading,
unloading, monitoring, deposition) into interlinked but separate
chambers. In this regard, it is an object of the invention to
couple these chambers to vacuum sources which can be pumped
independently of the remaining chambers, thereby limiting the
overall pump down time of the device when vacuum conditions are
broken in one of the separate chambers.
[0024] These and further objects of the invention are described in
more detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 illustrates a perspective view of a device used in
the high-throughput deposition of oxide thin films by reactive
coevaporation according to one preferred aspect of the
invention.
[0026] FIG. 2A illustrates a substrate support member
gravitationally held on a spindle.
[0027] FIG. 2B illustrates the underside of the substrate support
member shown in FIG. 2A.
[0028] FIG. 3A illustrates a substrate support member
gravitationally held on a spindle.
[0029] FIG. 3B illustrates the underside of the substrate support
member shown in FIG. 3A.
[0030] FIG. 4A illustrates a substrate support member that is held
circumferentially via a substrate support member holder.
[0031] FIG. 4B illustrates a substrate support member holder and
spindle.
[0032] FIG. 5A illustrates a deposition chamber wherein the motor
driving the spindle is located externally (top) with respect to the
deposition chamber.
[0033] FIG. 5B illustrates a deposition chamber wherein the motor
driving the spindle is located externally (bottom) with respect to
the deposition chamber.
[0034] FIG. 6A illustrates a motor coupled to a spindle via a
coupler.
[0035] FIG. 6B illustrates a motor coupled to a spindle via
gears.
[0036] FIG. 6C illustrates a motor coupled to a spindle via a
belt.
[0037] FIG. 7A illustrates a top down view of a heater element
having a slot therein for receiving a substrate support member. The
width of the slot is represented by angle .alpha..
[0038] FIG. 7B illustrates a top down view of a heater element
having a slot therein for receiving a substrate support member. The
width of the slot is represented by angle .beta..
[0039] FIG. 8A illustrates a heater element through which a spindle
passes.
[0040] FIG. 8B illustrates a heater element through which a spindle
partially passes.
[0041] FIG. 9 illustrates a substrate support member interposed
between a lower heater plate (e.g., zone) and an upper heater plate
(e.g., zone).
[0042] FIG. 10A illustrates one embodiment of a separable heater
element.
[0043] FIG. 10B illustrates another embodiment of a separable
heater element.
[0044] FIG. 10C illustrates another embodiment of a separable
heater element.
[0045] FIG. 10D illustrates another embodiment of a separable
heater element.
[0046] FIG. 10E illustrates another embodiment of a separable
heater element.
[0047] FIG. 11 illustrates an embodiment of a heater element that
is moveable with respect to a lower heater plate.
[0048] FIG. 12 illustrates an embodiment of a lower heater plate
that is moveable with respect to a stationary heater element.
[0049] FIG. 13 illustrates a substrate support member and a lower
heater plate that are moveable with respect to one another.
[0050] FIG. 14 illustrates a partially exploded view of the pocket
heater used inside the heater chamber of the device shown in FIG.
1.
[0051] FIG. 15 illustrates the top side of the lower plate heater
portion of the pocket heater. The oxygen pocket and window passing
through to the source chamber are illustrated.
[0052] FIG. 16A illustrates a side view of an alternative
embodiment of the pocket heater used inside the heater chamber of
the device shown in FIG. 1.
[0053] FIG. 16B illustrates a bottom, perspective view of the
pocket heater illustrated in FIG. 16A.
[0054] FIG. 17A illustrates a vertically oriented spindle holding a
substrate support member wherein the spindle passes through the top
of a deposition chamber.
[0055] FIG. 17B illustrates a vertically oriented spindle holding a
substrate support member wherein the spindle passes through the
bottom of a deposition chamber.
[0056] FIG. 18 illustrates an embodiment of a z-adjust assembly
wherein the motor and spindle are movable as a single unit.
[0057] FIG. 19A illustrates a front view of a z-adjust device
wherein a shaft of a motor is coupled via coupler to the
spindle.
[0058] FIG. 19B illustrates a side view of the z-adjust device of
FIG. 19A.
[0059] FIG. 19C illustrates a front view of a z-adjust device
wherein a shaft of a motor is coupled to the spindle via a
belt.
[0060] FIG. 20A illustrates a front view of a z-adjust device that
uses a horizontal feedthrough and an elliptically-shaped cam.
[0061] FIG. 20B illustrates a side view of the z-adjust device of
FIG. 20A.
[0062] FIG. 21A illustrates a front view of a z-adjust device that
uses a horizontally-oriented rotary feedthrough that drives a
scissor jack device to raise and lower a vertically oriented
support plate.
[0063] FIG. 21B illustrates a side view of the z-adjust device of
FIG. 21A.
[0064] FIG. 22 illustrates a z-adjust device that uses a
vertically-oriented rotary feedthrough driving a jack screw.
[0065] FIG. 23 illustrates a z-adjust device that uses a horizontal
feedthrough and cam to raise and lower the vertically-oriented
support plate.
[0066] FIG. 24 illustrates the spindle shaft and motor assembly
located on a vertical support plate.
[0067] FIG. 25 illustrates a substrate support member containing
substrates loaded on top of the lower plate heater.
[0068] FIG. 26 illustrates the spindle shaft and motor assembly
located on a vertical support plate.
[0069] FIG. 27 illustrates a cam device used to raise and lower the
spindle shaft and motor assembly shown in FIG. 26.
[0070] FIG. 28A illustrates one aspect of a load-lock chamber used
to store one or more QCMs.
[0071] FIG. 28B illustrates another aspect of a load-lock chamber
used to store one or more QCMs.
[0072] FIG. 29 illustrates a load-lock chamber having three QCMs
disposed therein.
[0073] FIG. 30 illustrates another embodiment of a load-lock
chamber in which the underside of the chamber includes a hole
therein for providing access to the deposition chamber.
[0074] FIG. 31A illustrates another embodiment of a load-lock
chamber. The valve to the load-lock chamber is located inside the
deposition chamber.
[0075] FIG. 31B illustrates another embodiment of a load-lock
chamber. The valve is disposed on the underside of the load-lock
chamber and provides access to the deposition chamber when
opened.
[0076] FIG. 31C illustrates a top down view of the load-lock
chamber shown in FIG. 31B.
[0077] FIG. 32 is a perspective view of the monitor chamber in an
open configuration showing the deposition monitors used to monitor
the evaporation of source material contained in the source
chamber.
[0078] FIG. 33A illustrates a substrate support member and
substrate according to one preferred aspect of the invention.
[0079] FIG. 33B illustrates a transfer chamber used to load a
substrate support member into the heater chamber of the device
shown in FIG. 1.
[0080] FIG. 34 illustrates a computer used in for controlling as
well as acquiring data from the device shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0081] FIG. 1 illustrates one embodiment of a device 2 used in the
high-throughput deposition of oxide thin films by reactive
coevaporation. The device 2 may also be used to deposit non-oxide
materials such as, for example, Magnesium diboride (MgB.sub.2).
U.S. patent application Ser. No. 10/726,232, entitled "Growth of
In-Situ Thin Films By Reactive Evaporation", incorporated by
reference as if fully disclosed herein, discloses a method of
forming MgB.sub.2 using a pocket heater device. It should be
understood that a variety of materials may be deposited using the
device 2. These include by way of illustration and not limitation,
complex oxides, ruthenates, manganates, titanates, -magnetic
materials, piezoelectrics, dielectrics, ferroelectrics,
semiconductors, nitrides, etc. The device 2 preferably includes
several subsystems located on a frame 4 or other support structure
which are integrated to form the overall device 2. The device 2 may
include a plurality of separate chambers, namely, a heater chamber
10, a source chamber 30, two transfer chambers 40, 50, and a
monitor chamber 60.
[0082] Heater chamber 10 is coupled to a source of vacuum 12 such
as, for example, a vacuum pump. The source of vacuum 12 is
separated from the heater chamber 10 by a valve 14 such as, for
instance, a gate valve. Prior to the deposition of HTS film, the
heater chamber 10 is evacuated using the source of vacuum 12.
[0083] The device 2 also includes a source chamber 30 which
contains the source of flux material (80a, 80b, 80c) used in the
deposition process. The source chamber 30 is similarly connected to
a source of vacuum 32 such as, for example, a vacuum pump. The
source chamber 30 is separated from the source of vacuum 32 by a
valve 34 such as, for instance, a gate valve.
[0084] A valve 36 is also disposed between the heater chamber 10
and the source chamber 30. Preferably, the valve 36 is a gate
valve. The gated arrangement advantageously allows the two chambers
(i.e., heater chamber 10 and source chamber 30) to be pumped to
vacuum separately. This is important because, for example, the flux
sources located in the source chamber 30 can be changed without
disturbing the heater chamber 10 or exposing it to atmospheric
conditions. Similarly, maintenance or the like can be performed on
components contained in the heater chamber 10 without disturbing
the vacuum conditions inside the source chamber 30. This
arrangement reduces the total amount of "pump down" time needed
because the volume of space that must be pumped is reduced by
isolating the various subsystems of the device 2. This aids in
increasing the overall throughput of the device 2.
[0085] Still referring to FIG. 1, the device 2 includes two
transfer chambers 40, 50 mounted on the external walls of the
heater chamber 10. Preferably, one transfer chamber 40 is a loading
chamber and the remaining transfer chamber 50 is an unloading
chamber. Both transfer chambers 40, 50 are coupled to a source of
vacuum 42, 52 such as, for example, a vacuum pump. The transfer
chambers 40, 50 may be coupled to separate sources of vacuum 42, 52
or, alternatively, the same source of vacuum. The two transfer
chambers 40, 50 are isolated from the heater chamber 10 by valves
41. Unloading chamber 50 may also be used as an oxygen soak.
[0086] In one aspect of the invention, the device 2 thus consists
of five separate vacuum chambers (i.e., heater chamber 10, a source
chamber 30, two transfer chambers 40, 50, and a monitor chamber 60)
that are linked to another via controllable valves. Of course, in
alternative embodiments, the device 2 may have fewer than five
chambers 50 or, alternatively, more than five chambers 50. Each of
these chambers may be pumped to vacuum pressures independent of the
other chambers if desired. In this regard, any one or multiple
chambers may be vented to atmosphere while the remaining chambers
remain under vacuum. This eliminates the need to pump down the
entire device 2 each time it is opened, for example, to clean parts
of the device 2, for reloading flux sources into the source chamber
30, for replacing and/or adjusting deposition monitors 64 in the
monitor chamber 60 or in the heater chamber 10, for
loading/unloading of the substrate support member 110 (e.g.,
carrier) into the heater chamber 10, or for maintenance or the like
on the components in one or more the chambers.
[0087] Referring to FIGS. 2A, 2B, 3A, 3B, 4A, 4B, 5A, and 5B in one
aspect of the invention, a substrate support member 110 is held on
a vertically oriented spindle 112 through a center hole 113. The
vertically oriented spindle 112 may hold the substrate support
member 110 either from above or below. FIGS. 2A and 2B illustrate
an embodiment wherein the substrate support member 110 is held from
below by the spindle 112 passing through the center hole 113. In
this embodiment, the substrate support member 110 is
gravitationally held by the spindle 112. In another embodiment, as
shown in FIGS. 3A and 3B, the vertically oriented spindle 112 holds
the substrate support member 110 from above. For example, the
spindle 112 may pass through a center hole 113 and terminate in an
attachment member 115 that secures the substrate support member
110. In yet another embodiment, as shown in FIGS. 4A and 4B,
substrate support member 110 is held circumferentially via a
substrate support member holder 117.
[0088] The substrate support member 110 may be rotated by
rotational movement of the spindle 112. A frictional fit between
the substrate support member 110 and spindle 112 imparts rotational
movement of the spindle 112 to the substrate support member 110.
The spindle 112 (and thus substrate support member 110) may be
driven via a motor (such as motor 122 described below). The motor
122 may be located either within a deposition chamber (e.g.,
chamber 10) containing the substrate support member 110 or external
to the deposition chamber 10, as shown in FIGS. 5A and 5B. In the
case where the motor is located outside the deposition chamber 10
holding the substrate support member 110, the spindle 112 may be
connected to a rotary vacuum feedthrough located either above or
below the substrate support member 110 and vacuum chamber. The
motor may be mechanically coupled directly to the spindle 112 as is
shown in FIGS. 5A and 6A. Alternatively, the motor may be
mechanically coupled to the spindle 112 via gears 111, belt 126,
chain, or the like, for example, as shown in FIGS. 5B, 6B and
6C.
[0089] As stated above, the substrate support member 110 is at
least partially contained in a heater chamber 10 that is used
during thin-film formation. In one aspect of the invention, the
heater chamber 10 contains a pocket heater 100 that is a
near-blackbody radiator. The pocket heater 100 may include one or
more heating elements 101 (e.g., zones) and a slot 10b (as shown in
FIGS. 7A and 7B) contained therein through which a substrate
support member 110 may be inserted and retracted via a transfer
mechanism (e.g., a transfer arm). The spindle 112 may then be
extended from either above or below the heater 100 in order to
support and rotate the substrate support member 110. FIGS. 8A and
8B illustrate two exemplary embodiments wherein the spindle 112
passes through a heating element in the heater chamber 10.
[0090] The above arrangement permits the substrate support member
110 to be introduced into and removed from the heater in one
direction, for example, as shown in FIG. 7A. Alternatively, as
shown in the embodiment in FIG. 7B, the substrate support member
110 may be introduced into and removed from the heater in multiple
directions (e.g., from the sides) by use of a longer slot
10(b).
[0091] During the thin film formation process, there may be a
minimum temperature above which the substrate support member 110
cannot be removed from the heater chamber 10. This may be because
the substrate support member 110 is too hot or because the films
being deposited (e.g., (RE)BCO) are too far above their structural
phase transition temperature to be removed from the heater chamber
10. Consequently, if the substrate support member 110 remains in
close proximity to the heater element 101, the cooldown time of the
substrates 116 (e.g., wafers) will be limited to that of the heater
element 101. Because the substrate support member 110 should be
heated uniformly, the heater element 101 is generally large and
requires a long cooldown time. The overall cooldown time may be
reduced by using cooling coils or the like to extract heat
contained in the heater element 101 and substrate support member
110. Even using cooling devices such as coils and the like, the
cooldown time of the substrate support member 10 and associated
substrates 116 is limited by the heater components. Ideally, the
substrate support member 110 and substrates 116 may be rapidly
cooled by physically separating the substrate support member 110
(and substrates 116) from the heater element 101.
[0092] When a pocket heater 100 is used in the heater chamber 10,
the substrate support member 110 should be located close to the
oxygen pocket region because a small gap is required to be
maintained near the oxygen pocket. In one embodiment, the oxygen
pocket region may be formed integral with a lower heater zone or
element. In such case, the top and/or side heater zones may be
located farther from the substrate support member 10 as is shown,
for example, in FIG. 9 (showing top zone disposed some distance
from substrate support member 110). Such arrangement allows passage
of the substrate support member 110 into and out of the heater and
heater chamber 10. However, the heater zones would have to be
hotter than the desired substrate 116 temperature since the heater
100 is no longer acting as a blackbody radiator. If the oxygen
pocket is not heated directly, the heating element(s) 101 would
have to be far hotter than the desired temperature of the
substrates 116 which may make the design complicated and
impractical.
[0093] In one aspect of the invention, a solution is proposed to
physically separate the heater element(s) 101 from the substrate
support member 110 following deposition of a thin film. This may be
accomplished by moving the heating element(s) 101 away from the
substrate support member 10 or alternatively, moving the substrate
support member 10 away from the heating element(s) 101.
Advantageously, the substrate support member 110 may be removed
from the heating element(s) 101 so that it can be freely or
actively cooled in oxygen. Moreover, by moving the substrate
support member 110 relative to the heating element(s) 101 (or vice
versa) this aids in the transfer of the substrate support member
110 (and associated substrates 116) into and out of the deposition
chamber (e.g., heater chamber 10).
[0094] Assuming that the pocket heater 100 is or approximates a
blackbody-type oven, FIGS. 10A-E, 11, and 12 illustrate several
exemplary ways of moving the heating element(s) 101 relative to the
substrate support member 110. Generally, the embodiments shown in
FIGS. 10A-E, 111 and 12 permit the substrate support member 110 to
move in the vertical direction (i.e., raised) from a heater element
101 from either above or below and also to be moved horizontally
out of the heater chamber 10. FIG. 10A, for example, illustrates an
embodiment in which the heating elements 101 (e.g., top and side
heating zones, or top, side, and lower heating zones) are separated
into two halves by movement of each respective half in the
direction of arrows A and B. FIG. 10B illustrates an embodiment in
which a vertical hinge 107 is provided that permits the two halves
to open. FIG. 10C illustrates an embodiment in which a horizontally
positioned hinge 107 permits the opening of the top and side heater
elements 101. FIG. 10D illustrates an embodiment wherein a
horizontally positioned hinge 107 permits the top heater element
101 or zone to flip open with respect to the remaining heater
element 101 (e.g. side heater element). In yet another embodiment,
as shown in FIG. 10E, a vertical hinge 107 permits the top heater
element 101 to pivot or swing with respect to the remaining heater
element(s) 101.
[0095] FIGS. 11 and 12 illustrate additional embodiments in which
the heater element 101 includes a bottom heater element or zone
101a (e.g., lower heater plate) and two upper heater elements or
zones 101b, 101c (e.g., heater cap). In one aspect, as shown in
FIG. 11, the two upper heater zones 101b, 101c are moved vertically
with respect to the lower heater zone 101a, thereby enabling
separation of the heater element 101 from the substrate support
member 110 contained therein (not shown in FIGS. 11 and 12). In
still another embodiment, as shown in FIG. 12, the upper heater
zones 101b, 101c remain fixed and the lower heater zone 101a is
moveable in a vertical direction. FIG. 13 illustrates a heater
element 101a that is moveable with respect to a moveable substrate
support member 110. This heater element 101a may or may not
incorporate an oxygen pocket.
[0096] In one aspect of the invention, the heater chamber 10
contains a rotationally driven pocket heater 100 which is used to
deposit and/or grow multi-component HTS oxide thin films. FIG. 14
illustrates the various components used for the pocket heater 100.
The pocket heater 100 includes heated cap portion 102 (e.g., upper
heating zone 101b as shown in FIGS. 11 and 12) which includes a
circular upper plate surface 102(a) and a downwardly projecting
cylindrical side wall 102(b) (heating zone 101c as shown in FIGS.
11 and 12) which forms an interior portion 102(c) into which
various components of the pocket heater 100 are inserted (described
below). The heated cap portion 102 may be fabricated from insulated
heater wire (heating element) that is wrapped to form the upper
surface 102(a) and the cylindrical side 102(b) wall. Preferably,
the upper surface 102(a) and the cylindrical side wall 102(b) each
are formed from a single segment of insulated wire such that the
upper surface 102(a) and cylindrical side wall 102(b) may be heated
independently of one another for temperature uniformity. Current is
run through the insulated wires to generate heat.
[0097] The heated cap portion 102 of the pocket heater 100 is
advantageously moveable in the z-direction to open the pocket
heater 100 so that the substrate support member 110 (described
below) can be loaded into the pocket heater 100 prior to thin-film
deposition and removed after deposition. The heated cap portion 102
is, for instance, secured to an actuator 103 which extends through
a top wall of the heater chamber as is seen in FIG. 1. The actuator
103 provides the vertical movement (i.e., motion in the
z-direction) to the heated cap portion 102 of the pocket heater
100.
[0098] Referring to FIG. 14 and FIG. 15, in one aspect of the
device, the pocket heater 100 includes a lower heater plate 104
(e.g., lower heater zone 101a as shown in FIGS. 11 and 12) which is
a third, independent heating zone. The lower plate heater 104 is
stationary and may be anchored to the top, bottom, or side walls of
the heater chamber 10. The lower heater plate 104 is preferably
formed from a single piece of metal, preferably INCONEL, that is
machined into the desired shape. Of course, the heater plate 104
may be formed from other materials. The lower plate heater 104 is
machined to include a window opening 104(a) (best seen in FIG. 15)
which passes completely through the plate and is exposed to the
source chamber 30 and source flux contained therein.
[0099] The lower plate heater 104 further includes a pocket 104(b)
(as best seen in FIG. 15) which is machined into the upper surface
of the lower plate heater 104. During operation of the device 2,
for example, oxygen (O.sub.2) gas is introduced into the pocket
104(b) for the reaction portion of thin-film growth/deposition. The
oxygen gas is introduced into the pocket 104(b) by one or more
ports 105. The underside of the lower plate heater 104(c) includes
a pocket (not shown) into which is brazed insulated thermal wiring.
Current is run through this wiring to heat the lower plate heater
104. U.S. Pat. No. 5,126,533, which is incorporated by reference as
if set forth fully herein, discloses a method of brazing insulated
wire to form a heater of this type.
[0100] Alternatively, a wholly separate oxygen pocket member 108
may exist independent of the lower heater zone. The oxygen pocket
member 108 includes an oxygen pocket 108a that may not be part of
the lower heater zone, as shown, for example, in FIGS. 16A and 16B.
Thus, the oxygen pocket member 108 may or may not contain heating
elements. Generally, the purpose of the oxygen pocket 108a is to
provide a localized region of oxygen adjacent to the substrates for
film oxidation. In this arrangement, the oxygen pocket member 108
and substrate support member 110 both are contained within the
quasi-blackbody heater, the heating elements of which may surround
both the oxygen pocket member 108 and support plate on multiple or
all sides. The oxygen pocket member 108 is preferably formed from a
single piece of metal, such as, for example, INCONEL, that is
machined into the desired shape. Of course, the oxygen pocket
member 108 may be formed from other materials. The oxygen pocket
member 108 is machined to include a window opening 108b which
passes completely through the member 108 and is exposed to the
source chamber 30 and source flux contained therein. In this
embodiment, the lower heater zone 101a may be fabricated from
insulated heater wire (heating element) that is wrapped. The lower
heater zone 101a may be formed from a single segment of insulated
wire such that the lower heater zone 101a, and heater zones 101b,
101c may be heated independently of one another for temperature
uniformity.
[0101] Referring back to FIG. 14 and FIG. 16A, the pocket heater
100 preferably includes a heat shield 106 disposed beneath the
lower plate heater 101a. As seen in FIG. 14, the heat shield 106
includes a window 106(a) therein which provides access to the
window opening 104(a) of the lower plate heater 104 and to the
source chamber 30 containing the source of flux.
[0102] With reference now to FIGS. 17A, 17B, 18, 19A, 19B, 19C,
20A, 20B, 21A, 21B, 22, and 23, a z-adjust assembly 121 is provided
to adjust the gap between the rotating substrate support member 110
and the oxygen pocket 104(b) which may exist in the lower plate
heater 104 (as shown, for example, in FIGS. 14 and 15) or as part
of a separate oxygen pocket member 108. The width of the gap is
important in order to maintain a high differential pressure between
the oxygen pocket 104b, 108a and the deposition chamber. A small
and uniform gap is desirable because it maximizes the oxygen
pressure in the pocket 104b, 108a while minimizing any leakage of
oxygen out of the pocket 104b, 108a. In addition, a small and
uniform gap minimizes the background pressure in the deposition
chamber. The size of the gap depends on the temperature of the
lower plate heater 104 or of the oxygen pocket member 108 and the
substrate support member 110 as well as their respective thermal
histories. These components expand and contract as a function of
temperature and they also distort to different degrees depending on
the temperature profile and heater ramp cycle.
[0103] There thus is a need to adjust the gap in situ at any time
during the heating cycle and deposition run in order to maintain
the optimal gap width. To accomplish this, either the substrate
support member 110 (containing the substrates 116) or the lower
plate heater 104 or oxygen pocket member 108 need to be able to be
adjusted vertically as shown generally in FIG. 13.
[0104] In one aspect of the invention, the lower plate heater 104
or oxygen pocket member 108 is vertically adjusted through the use
of cams, scissors, jack screws, lead screws, servos, and other
mechanisms known to those skilled in the art. In another
embodiment, the substrate support member 110 is vertically adjusted
by vertical movement of the spindle 112 as is shown, for example,
in FIGS. 17A, 17B, 18, 19A, 19B, 19C, 20A, 20B, 21A, 21B, 22, and
23. FIG. 17A illustrates a z-adjustable spindle 112 that holds the
substrate support member 110 from the top and extends through the
top of the heater chamber 10. The spindle 112 may be connected or
coupled to a motor (not shown) to rotationally drive the spindle
112 and substrate support member 110. The spindle 112 may be
adjusted in the vertical direction (arrow A) by using a linear
vacuum feedthrough or linear slide (or other compatible z-adjust
mechanisms). FIG. 17B illustrates an embodiment in which the
spindle 112 holds the substrate support member 110 from below and
extends through the bottom of the heater chamber 10. The spindle
112 may be rotationally driven and raised/lowered in the direction
of arrow A.
[0105] In one aspect of the invention, as shown in FIG. 18, the
entire spindle 112 is located inside the deposition chamber (i.e.,
heater chamber 10) and is driven via an in-vacuum motor assembly
such as in-vacuum motor 122 described in more detail below.
[0106] The spindle 112 may be moved separately from the in-vacuum
motor 122 if suitable coupling mechanisms are employed. Preferably,
as disclosed below, the motor 122 and spindle 112 are moved
together as a unit. FIGS. 19A and 19B illustrate an embodiment
wherein a shaft of the motor 122 is coupled via coupler 123 to the
spindle 112. The motor 122 is secured or otherwise attached to a
vertically oriented support plate 118. FIG. 19C illustrates an
alternative embodiment in which the in-vacuum motor 122 is secured
to the spindle 112 via a belt 126 or the like.
[0107] FIGS. 20A and 20B illustrate an embodiment in which a rotary
shaft 125 drives a rotatable cam 127 that moves a vertically
oriented support plate 118. FIGS. 21A and 21B illustrate a
horizontally-oriented rotary shaft 125 that drives a scissor jack
device 129. FIG. 22 illustrates a vertically-oriented rotary shaft
125 driving a jack screw 131. In another embodiment, as shown for
example in FIG. 23, a linear feed-through 133 drives a cam 132 that
engages the vertically oriented support plate 118. In still another
aspect of the invention, a second in-vacuum motor (not shown) may
be used to drive the shaft/feedthrough (125, 133) and cam (127,
133), thereby minimizing the number of feedthroughs into the vacuum
chamber.
[0108] Referring to FIG. 24 and FIG. 25, in one preferred aspect of
the invention, a vertically oriented support plate 118 contains the
spindle shaft and motor assembly 120 (z-adjust assembly). The
support plate 118 is moveable in the z-direction as shown, for
example, by arrow A in FIG. 24. The spindle shaft and motor
assembly 120 includes a motor 122 (preferably an in-vacuum motor
122) affixed to the support plate 118. The in-vacuum motor 122
includes a drive shaft 124 that is mechanically coupled to the
spindle shaft 112(a) via a belt 126 or other linkage assembly. The
in-vacuum motor 122 provides variable speed rotation to the
substrate support member 110. The support plate 118 further
includes a roller 128 that is used to move the spindle shaft and
motor assembly 120 in the z-direction (explained in more detail
below). In an alternative configuration, the motor assembly 120 may
be provided ex-situ rather than in-situ.
[0109] Referring to FIG. 24 and FIG. 25, in one aspect of the
invention, the substrate support member 110 is held between the
upper heater zones 101b, 101c of the pocket heater 100 and the
lower heater zone 101a. The spindle 112 passes through center holes
located in the heat shield 106 and lower plate heater 104. The
spindle 112 is rotatably coupled to a motor (described in more
detail below) and is also movable in the z direction as shown by
arrow A in FIG. 24.
[0110] FIG. 25 illustrates a substrate support member 110 held on
the rotatable spindle 112. The substrate support member 110 is
preferably held gravitationally on an upper end of the spindle 112.
The substrate support member 110 includes a plurality of holes 114
cut into the substrate support member 110 that accept and hold
substrates 116 onto which the HTS material is deposited. The
substrates 116 may include substrates formed from, for example,
magnesium oxide (MgO). Other materials may, of course, be used in
accordance with the invention described herein. The substrates 116
are preferably gravitationally held in place by small fingers or a
ridge located along the lower edge of the substrate support member
110 where the holes 114 are located. Thus, the substrate support
member 110 allows for essentially contact-less suspension of the
substrates 116 during the heating and deposition process.
[0111] In addition, this configuration permits the growth and/or
deposition of HTS thin films on a single side of the substrate 116,
namely, the lower side of the substrates 116(a) as seen in FIG. 25.
The upper side (or backside) of the substrates 116(b) is
undisturbed and may be deposited in a subsequent deposition process
by turning the substrate 116 over.
[0112] The substrate support member 110 may be designed to
accommodate a smaller number of larger diameter substrates 116 or a
larger number of smaller diameter substrates 116. In addition, the
holes 114 in the substrate support member may also be designed to
accommodate substrates 116 having different shapes.
[0113] The device 2 advantageously permits the substrate support
member 110 to be introduced into the heater chamber 10 in situ when
the pocket heater 100 is opened, i.e., when the heated cap portion
102 is raised from the lower heater plate 104. The heated cap
portion 102 is then lowered over and around the substrate support
member 110 during the run and can then be raised at the end of the
run or at such time when the pocket heater 100 has cooled
sufficiently. This ability to open the pocket heater 100 and
load/unload the substrate support member 100 improves the cycle
time of the deposition process because the substrate support member
110 does not have to be attached to the pocket heater 100 when the
pocket heater 100 is cold. Rather, the substrate support member 110
can be loaded/unloaded after the pocket heater 100 is only partway
through its heat-up and cool-down cycle.
[0114] In an alternative embodiment, the substrate support member
110 allows for gripping the substrates 116 from both the lower
116(a) and upper surfaces 116(b) of the substrates simultaneously
such that the entire substrate support member 110 may be flipped
over between deposition runs. Preferably, the substrate support
member 110 can be flipped over in-situ within the heater chamber 10
or within the transfer chambers 40, 50 such that HTS material can
be deposited onto the second side of the substrate 116 (e.g., the
upper side 116(b)) without having to break vacuum in the device 2,
thereby significantly increasing the throughput of the device 2 and
process. In this embodiment, the transfer arm 45 may be rotatable
about its long axis to flip the substrate support member 110 from
one side to another.
[0115] FIG. 26 illustrates the in-vacuum motor 122 used in
accordance with a preferred aspect of the invention. The in-vacuum
motor 122 includes a motor 122(a) housed inside an enclosed
pressure vessel 122(b). The pressure vessel 122(b) effectively
isolates the motor 122(a) from the vacuum conditions inside the
heater chamber 10. The drive shaft 124 extends from the interior of
the pressure vessel 122(b) to the outside of the pressure vessel
122(b) via a vacuum feedthrough (not shown). A pressure line 122(c)
is secured to the pressure vessel 122(b) and delivers pressurized
dry air inside the space of the pressure vessel 122(b) surrounding
the motor 122(a). The pressurized dry air removes heat from the
motor 122(a). Another conduit 122(d) is coupled to the pressure
vessel 122(b) for delivering power and other control wires needed
to operate the motor 122(a).
[0116] In an alternative embodiment, the motor 122 may include an
air or gas-driven motor which is powered by a source of compressed
or otherwise pressured source of air or gas. Mechanical,
electrical, or even optical feedback may be employed for speed
control of the motor 122.
[0117] FIG. 27 illustrates an exemplary cam device 130 used to
impart z-direction movement (arrow A in FIG. 27) in the spindle
shaft and motor assembly 120. The cam device 130 includes a cam 132
having multiple inclined surfaces 132(a) and 132(b) for engaging
with the roller 128 secured to the support plate 118. Preferably,
the cam 132 is machined from a solid piece of stainless steel
plate. First inclined surface 132(a) is inclined at an angle
.alpha. while the second inclined surface 132(b) is inclined at an
angle .beta.. Preferably, angle .beta. is greater than angle
.alpha.. The different angles permit rough and fine course
adjustments of the z-direction of the spindle shaft and motor
assembly 120. In an alternative configuration, the cam 132 may have
a surface in the form of a continuous or semi-continuous arc (not
shown).
[0118] The cam 132 is moveable in the horizontal direction (arrow B
in FIG. 27) by an actuator 134 which is connected to the cam 132
via a feed-through 133. Preferably, the actuator 134 is located
external to the heater chamber 10 and includes a feed-through 133
passing through a side wall of the heater chamber 10. The movement
of the actuator 134 is preferably controlled by a computer 200 (See
FIG. 34) or microprocessor which allows dynamic movement of the
spindle 112 (and thus substrate support member 110) in real time
during the deposition process. In this regard, the gap between the
substrate support member 110 holding the substrates 116 and the
lower heater plate 104 can be optimized.
[0119] During operation of the device 2, the second inclined
surface 132(b), that is the surface with the steeper inclination,
is used when the substrate support member 110 needs to be raised
and lowered from the lower heater plate 104 for purposes of loading
and unloading and for separating the support member 110 from the
heater assembly. In contrast, the first inclined surface 132(a),
namely, the surface with the shallower inclination, is used to
allow fine z-axis adjustment of the substrate support member 110
for placing the substrate support member 110 as close as possible
to the lower heater plate 104, thereby adjusting the gap between
the substrate support member 110 and the lower heater plate
104.
[0120] The evaporation rate of metal species used to form HTS thin
films should be carefully monitored and controlled in order to
produce the desired film composition. While it has been known to
use QCMs and associated electronics to monitor this deposition
process, these crystals must generally be replaced after every
deposition run, particularly because the signals generated by the
crystals tend to become noisy from large amounts of deposited
materials and oxides. Opening the heater chamber 10 for the purpose
of replacing these crystals is undesirable, however, because the
large volume of the heater chamber 10 must then be cleaned and
pumped again to vacuum. This adversely affects the throughput of
the device. The present device 2, however, with the separate
monitor chamber 60 allows for the replacement of the deposition
monitors 64 (e.g., QCMs) without disturbing the heater chamber 10
(or other chambers).
[0121] FIGS. 28A, 28B, 29, 30, 31A, 31B, and 31C illustrate aspects
of the monitor chamber 60 in which the QCMs (or other rate, flux,
or thickness monitors) are retractable within a load-locked chamber
70 or housing that is differentially pumped. The load-locked
chamber is coupled to a source of vacuum 68 to provide the
differential pumping aspect. The advantage of this embodiment is
that it permits the replacement of QCMs (or other sensors) without
breaking vacuum and opening the deposition chamber either during a
run or between runs. In addition, the vacuum pumped load-locked
chamber 70 minimizes the QCM from oxygen exposure which degrades
their rate monitoring abilities.
[0122] FIG. 28A illustrates a load-locked chamber 70 connected to a
main deposition chamber (e.g., heater chamber 10). The load-locked
chamber 70 includes a valve 72 such as a gate valve to separate the
interior of the deposition chamber from the interior of the
load-locked chamber 70. As seen in FIG. 28A, a vacuum bellows drive
mechanism 73 is used to move the QCMs (sensor(s) 64) laterally into
and out of the deposition chamber. FIG. 28B illustrates an
alternative aspect of the invention in which the QCMs 64 are moved
into and out of the deposition chamber using a magnetically-coupled
transfer arm mechanism 74 that includes a moveable external magnet
74a that is used to drive a magnetic transfer 74b arm. FIG. 29
illustrates three QCMs which are retractable within a single
load-locked chamber 70 through a valve 72. Alternatively, a
separate load-locked chamber 70 may be used for each QCM.
[0123] FIGS. 30, and 31A-C illustrate an embodiment wherein the
load-locked chambers 70 extend into the deposition chamber 10 and
are continually pumped using a source of vacuum 68 to reduce the
amount of residual oxygen near the QCM heads. FIG. 30, for example,
illustrates a load-locked chamber 70 having a slit or hole 75
located on the underside of the chamber 70 such that evaporated
species can enter the chamber 70 and be deposited on the QCMs 64. A
valve 72 separates the interior of the deposition chamber 10 from
the interior of the load-locked chamber 70. Multiple QCMs may be
incorporated into a single load-locked chamber 70 (e.g., three
QCMs).
[0124] In an alternative embodiment, as shown in FIG. 31A, the
valve 72 may be located on the load-locked chamber 70 such that the
valve 72 is within or inside the deposition chamber 10.
Alternatively, the valve 72 may form the slit itself (e.g., slit
valve) as is shown in FIGS. 31B and 31C. By opening the slit valve
72, the evaporated species are then exposed to the QCMs.
[0125] The elements of FIGS. 31B and 31C are incorporated into one
preferred embodiment of the monitor chamber 60 used in connection
with the device 2. This preferred embodiment is illustrated in FIG.
32. The monitor chamber 60 includes a front face plate 62 that is
slidable within the monitor chamber 60. The slidable front face
plate 62 permits easy access to one or more deposition monitors 64
positioned on the rails 65. The deposition monitors 64 are aimed
downward toward the source chamber 30 and preferably include
dividers or the like (not shown) that direct each monitor 64 to a
particular flux source in the source chamber 30. In a preferred
aspect of the invention, the deposition monitor 64 is a crystal
quartz monitor (QCM).
[0126] The deposition monitors 64 are located on the rails 65 such
that when the front face plate 62 is closed against the monitor
chamber 60, the deposition monitors 64 are disposed above a slit
valve 66 located on the underside of the monitor chamber 60. The
slit valve 66 opens/closes access to the source chamber 30
containing the flux sources. In this manner, the monitor chamber 30
is load-locked from the source chamber 30 via the slit valve
66.
[0127] When the slit valve 66 is open, the deposition monitors 64
are exposed to the evaporated flux that rises from the source
chamber 30 into the heater chamber 10, and thus the deposition rate
of the flux species may be monitored. When the slit valve 66 is
closed, the monitor chamber 60 may be vented to atmosphere
separately from the other chambers, and the deposition monitors 64
removed from the monitor chamber 60 using the slidable front face
plate 62. In this manner, the deposition monitors 64 may be
inspected and replaced without disturbing the rest of the vacuum
system.
[0128] Still referring to FIG. 32, a vacuum source 68 such as, for
example, a vacuum pump, is coupled to the monitor chamber 30 and is
used to pump down the monitor chamber 30 during operation of the
device 2. The vacuum source 68 is preferably a high vacuum pump
such as, for instance, a turbomolecular pump.
[0129] In addition, as explained above, QCMs can become unreliable,
particularly in the presence of oxygen and oxides. Should a QCM
fail during a run, the device 2 allows the replacement of the QCM
during the deposition run without stopping the deposition process.
Therefore, run efficiency and throughput are greatly enhanced in
the event of QCM failure. In addition, the slit valve 66 can be
closed following deposition prior to the time when the heater
chamber 10 is flooded with oxygen, thereby further minimizing the
amount of contact between the QCMs and oxygen/oxides.
[0130] A device that uses multiple, rotatable quartz crystals
inside the heater chamber 10 may also be used, thereby limiting the
number of times in which the crystals need to be changed (the
device rotates to the next crystal thereby avoiding pump down
between runs). Atomic absorption techniques may also be employed to
monitor the deposition process. For example, radiation beams used
in atomic absorption measurements may be passed through the
deposition plume inside the heater through entry and exit ports or
windows located in the heater chamber 10 (not shown).
[0131] With reference now to FIGS. 33A and 33B, in one aspect of
the device 2, two transfer chambers 40, 50 are provided for the
loading and unloading of the substrate support member 110
containing substrate(s) 116. FIG. 33B depicts one of the loading
transfer chamber 40. Both transfer chambers 40, 50, however, are
essentially identical and operate in the same manner. As seen in
FIG. 1, the two transfer chambers 40, 50 are located directly
across from one another on each side of the heater chamber 10. Of
course, the transfer chambers 40, 50 may be located on different
sides or the same side of the heater chamber 10. A slit in the wall
of the heater chamber 10 allows passage of the substrate support
member 110 into and out the heater chamber 10. The heater chamber
10 is isolated from the two transfer chambers 40, 50 by valves 41
(see FIG. 1).
[0132] Referring back to FIG. 33B, during operation, the substrate
support member 110 is taken from a room temperature and pressure
environment and placed into the loading transfer chamber 40 using a
door 44 located on top of the transfer chamber 40. When the door 44
is closed, the transfer chamber 40 is pumped to vacuum using a
source of vacuum 42 (52 in the case of unloading transfer chamber
50). The substrate support member 110 is placed on an extendable
transfer arm 45 including multiple tines 47 for holding the
substrate support member 110. The extendable transfer arm 45 is
moveable in the direction of arrow A shown in FIG. 33B.
[0133] A rotary drive disposed on the underside of the transfer
chamber 40 (not shown) provides horizontal displacement of the
transfer arm 45 using magnetic coupling. In this regard, the
motorized components are contained outside the transfer chambers
40, 50. By magnetically coupling the transfer arm 45 to the
external rotary drive, there is no need to expose the drive
mechanism to a vacuum environment.
[0134] When the transfer chamber 40 has been pumped to vacuum, the
valve 41 (as seen in FIG. 1) connecting the transfer chamber 40 the
heater chamber 10 is opened, and the substrate support member 110
is extended into the heater chamber 10 by activating the rotary
drive.
[0135] For unloading operations, the reverse sequence of events
occurs in the unloading transfer chamber 50. In particular, the
transfer arm 45 retrieves the substrate support member 110 from the
heater chamber 10 and retracts into the transfer chamber 50. The
transfer chamber 50 can then be vented to atmosphere or a soak
routine can be employed. The door 44 can then be opened and the
substrate support member 110 retrieved.
[0136] An optional heater (not shown) may be included in the
transfer chamber 40 to pre-heat the substrate-laden substrate
support member 110 prior to introduction into the heater chamber
10. Preferably, the substrate support member 110 is heated
radiatively. This pre-heating may be accomplished by heater lamps,
coils, or other heating elements disposed on the transfer chamber
40.
[0137] Referring back to FIG. 1, the source chamber 30 of the
device 2 includes one or more evaporation sources e.g., sources
80a, 80b, and 80c. The sources 80a, 80b, and 80c may include
crucibles 81a, 81 b, 81c, boats, or the like filled with source
material. As one example, Yttrium (Y) might be placed in crucible
81a while Copper (Cu) might be placed in crucible 81b. Source
material is placed inside the crucible 81a, 81b, 81c or similar
structure and heated to evaporation temperatures. For example, an
e-gun assembly or the like may be used to heat the source material.
As one additional example, the source material may include Barium
(Ba) in the case of YBCO thin films. It should be understood that
the sources 80 (e.g., 80a, 80b, 80c) may be evaporated using any
technique including, but not limited to, electron beams, Knudsen
cells, resistive boats, sputtering, laser ablation, etc.
[0138] The following is a description of a process used to deposit
YBCO or other oxide films using reactive coevaporation.
[0139] First, the quartz crystals used to monitor the overall flux
in the heating chamber 10 are replaced by first venting the heater
chamber 10, opening the heater chamber door 10(a), replacing the
quartz crystals, closing the heater chamber door 10(a), and pumping
down the heater chamber 10 to vacuum conditions.
[0140] Next, the deposition monitors 64 (e.g., QCMs) are changed in
the monitor chamber 60. This is accomplished by venting the monitor
chamber 60, opening the front face 62, replacing the deposition
monitors 64, close the front face 62, and pumping down the
deposition monitor 64 to vacuum conditions.
[0141] If necessary, source materials are loaded into crucibles
81a, 81b, 81c (or other source holders). In this procedure, the
source chamber 30 is vented to atmosphere and opened. Additional
and/or replacement source material is loaded into one or more of
the crucibles 81a, 81b, 81c. The source chamber 30 is then closed
and pumped to vacuum.
[0142] Substrates 116 are loaded in the device 2 by initially
loading one or more substrates 116 onto the substrate support
member 110. Transfer chamber 40 is vented to atmosphere and the
door 44 is opened. The loaded substrate support member 110 is then
placed on the tines 47 of the transfer arm 45. The door 44 is then
closed and the transfer chamber 40 is pumped to vacuum. The valve
41 between the transfer chamber 40 and the heater chamber 10 is
opened to provide access to the heater chamber 10. In addition, the
heated cap portion 102 of the pocket heater 100 is raised by the
actuator 103. The transfer arm 45 containing the substrate support
member 110 is then extended into the heater chamber 10.
[0143] When the substrate support member 110 is centrally located
beneath the heated cap portion 102 of the pocket heater 100, the
spindle 112 is raised in the z-direction to engage the substrate
support member 110. The substrate support member 110 is lifted off
the tines 47 of the transfer arm 45 by the raised spindle 112. The
transfer arm 45 is then withdrawn back into the transfer chamber
40. The valve 41 is closed and the spindle 112 is lowered to the
desired height to form the gap between the substrate support member
110 and the lower heater plate 104.
[0144] Next, the upper heater zones 101b, 101c of the pocket heater
100 are lowered into position using the actuator 103. Rotation of
the substrate support member 110 is then initiated. The substrate
support member 110 is lowered toward the lower heater plate 104
until the desired gap is established. Oxygen flow is initiated to
the reaction pocket, and the flow rate and gap (i.e., distance
between the substrate support member 110 and lower heater plate
104) are adjusted to provide the desired oxygen pressure inside the
pocket. The heater coils are energized to ramp the pocket heater
100 to the desired temperature. The source materials are then
evaporated. At this point, the gate valve 36 is opened between the
heater chamber 10 and the source chamber 30. A shutter is
interposed between the substrate support member 110 and source
chamber 30 to prevent deposition onto the substrates 116. A second
shutter located in the source chamber that is interposed between
the source materials and the gate valve 36 is also opened. The slit
valve 66 in the monitor chamber 60 is opened and evaporation rates
of the source materials are adjusted based on measurements made
with the deposition monitors 64.
[0145] Once the pocket heater 100 is at the desired temperature and
the desired rates of evaporation of the source materials are
reached, the shutter interposed between the substrate support
member 110 and source chamber 30 is opened to allow deposition onto
the rotating substrates 116.
[0146] Once the desired thickness of film has been reached, the
first and second shutters described above are closed. After the two
shutters are closed, the gate valve 36 between the heater chamber
10 and the source chamber 30 is closed. The heater chamber 10 is
then backfilled with oxygen gas. The temperature of the pocket
heater 100 is then ramped down. The crucibles 81a, 81b, 81c are
then cooled down. Once the heater chamber 10 (or pocket heater 100)
temperature is low enough, the heated cap portion 102 of the pocket
heater 100 is raised in the vertical direction via the actuator
103. The substrate support member 110 is raised from the lower
heater plate 104 using the moveable spindle 112.
[0147] With the substrate support member 110 raised form the lower
heater plate 104, the pressure in the transfer chamber (unloading)
50 is equalized with the pressure of the heater chamber 10 using an
equalization circuit. The valve 41 is opened and the transfer arm
45 is extended into the heater chamber 10. The substrate support
member 110 is then lowered onto the tines 47 of the transfer arm 45
using the cam device 130. The transfer arm 35 (and substrate
support member 110) is then withdrawn back into the transfer
chamber 50 and the valve 41 is closed. When the substrate support
member 110 is cool, the transfer chamber 50 is vented to
atmosphere. The door 44 can be opened and the substrate support
member 110 containing the HTS thin film-laden substrates 116 is
removed.
[0148] In a preferred aspect of the invention, the device 2 and
process described above is run by a computer 200 such as that shown
in FIG. 34 (i.e., microprocessor) having software loaded thereon
that is able to control and monitor the deposition process. The
computer 200 advantageously controls the pumps, heaters, valves,
transfer arms, actuators, motors, cam device, flux sources and the
like. In addition, the computer 200 is able to acquire data from
the device 2 such as, for example, temperatures and pressures in
the various chambers of the device. The computer 200 also receives
data from the deposition monitors 64 in order that the deposition
process can be monitored during a particular run. Preferably, the
software is implemented using a graphical user interface (GUI)
making the software user friendly.
[0149] While the invention is susceptible to various modifications,
and alternative forms, specific examples thereof have been shown in
the drawings and are herein described in detail. It should be
understood, however, that the invention is not to be limited to the
particular forms or methods disclosed, but to the contrary, the
invention is to cover all modifications, equivalents and
alternatives falling within the spirit and scope of the appended
claims.
* * * * *