U.S. patent application number 10/931413 was filed with the patent office on 2005-02-10 for method and apparatus for creating radial profiles on a substrate.
This patent application is currently assigned to Symyx Technologies, Inc.. Invention is credited to Ramberg, C. Eric, Wang, Youqi.
Application Number | 20050029089 10/931413 |
Document ID | / |
Family ID | 34119651 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050029089 |
Kind Code |
A1 |
Wang, Youqi ; et
al. |
February 10, 2005 |
Method and apparatus for creating radial profiles on a
substrate
Abstract
The gradient deposition method and apparatus permits a radial
thickness or composition gradient on a substrate to be formed. The
system comprises one or more deposition sources that can be fired
sequentially or simultaneously. The system also comprises one or
more dynamic shutters (e.g., shutters that can be moved
independently of each other and during the deposition of a
material) in combination with equipment that permits the substrate
to be rotated during the deposition of the material onto the
substrate. The system may also include one or more contact masks
that may be placed on the substrate during the deposition in order
to mask off particular portions of the substrate during the
deposition process.
Inventors: |
Wang, Youqi; (Atherton,
CA) ; Ramberg, C. Eric; (San Jose, CA) |
Correspondence
Address: |
SYMYX TECHNOLOGIES INC
LEGAL DEPARTMENT
3100 CENTRAL EXPRESS
SANTA CLARA
CA
95051
|
Assignee: |
Symyx Technologies, Inc.
|
Family ID: |
34119651 |
Appl. No.: |
10/931413 |
Filed: |
August 31, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10931413 |
Aug 31, 2004 |
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10114589 |
Apr 1, 2002 |
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6830663 |
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10931413 |
Aug 31, 2004 |
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09237502 |
Jan 26, 1999 |
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6364956 |
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60334889 |
Nov 15, 2001 |
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Current U.S.
Class: |
204/192.12 ;
204/298.11 |
Current CPC
Class: |
B01J 2219/00605
20130101; B01J 2219/00596 20130101; B01J 2219/00659 20130101; B01J
2219/0043 20130101; B01J 2219/0059 20130101; C23C 14/027 20130101;
C40B 40/18 20130101; B01J 19/121 20130101; B01J 2219/00745
20130101; C40B 60/14 20130101; B01J 19/122 20130101; C23C 14/06
20130101; B01J 2219/00527 20130101; B01J 2219/00756 20130101; C23C
14/3464 20130101; B01J 2219/00443 20130101; B01J 2219/00603
20130101; B01J 2219/00621 20130101; B01J 19/127 20130101; B01J
19/0046 20130101 |
Class at
Publication: |
204/192.12 ;
204/298.11 |
International
Class: |
C23C 014/32 |
Claims
1. An apparatus for creating a radial profile of a target material
on a substrate, the apparatus comprising: a deposition source for
directing a target material for deposition on a substrate; a
shutter for blocking an amount of the target material from
depositing on the substrate; and a platform that holds the
substrate, wherein the substrate and shutter are adapted for
rotation relative to each other during the deposition of the target
material, such that the shutter blocks a predetermined amount of
the target material to generate a radial profile on the
substrate.
2. The apparatus of claim 1 further comprising a contact mask for
blocking all of the target material from striking a portion of the
substrate.
3. The apparatus of claim 1, wherein the platform holding the
substrate is rotatable and the shutter is not rotatable.
4. The apparatus of claim 3, wherein the rotatable platform is
rotatable at a constant speed.
5. The apparatus of claim 3, wherein the rotatable platform is
rotatable at a variable speed.
6. The apparatus of claim 3, further comprising a motor that is
controllable to move the shutter and change the location on the
substrate of the region that is blocked from deposition of the
target material.
7. The apparatus of claim 6, wherein the shutter is movable, such
that a gradient profile is generated during the deposition of the
target material on the substrate.
8. The apparatus of claim 6, wherein the shutter is movable at a
constant speed.
9. The apparatus of claim 6, wherein the shutter is movable at a
variable speed.
10. The apparatus of claim 6, wherein the shutter is adapted to be
initially positioned to block the target material at the center of
the substrate and is further adapted to move toward the edge of the
substrate while the substrate is rotated during deposition to
generate a conical profile on the substrate.
11. The apparatus of claim 6, wherein the shutter is adapted to be
initially positioned to block the target material at the edge of
the substrate and is further adapted to move toward the rotation
center of the substrate during deposition while the substrate is
rotated.
12. The apparatus of claim 3 wherein the shutter is a first
shutter, the apparatus further comprising a second shutter that is
independently movable relative to the first shutter.
13. The apparatus of claim 12, wherein the first and second
shutters are adapted to be initially positioned at opposite edges
of the substrate and are further adapted to move toward each other
and toward the center of the substrate during deposition.
14. The apparatus of claim 12, wherein the first and second
shutters are adapted to be initially positioned at the center of
the substrate and are adapted to move away from each other and
toward the opposite edges of the substrate during deposition.
15. The apparatus of claim 12, wherein the first and second
shutters are adapted to be placed at a fixed position during the
deposition to generate an annular ring of target material on the
substrate.
16. The apparatus of claim 12, wherein the first and second
shutters are adapted to be rotated during the deposition to
generate an annular ring of target material on the substrate.
17. The apparatus of claim 3 further comprising one or more
additional deposition sources for depositing one or more additional
target materials onto the substrate and one or more additional
shutters for blocking an amount of the one or more additional
target materials from depositing on the substrate.
18. The apparatus of claim 1, wherein the shutter is rotatable
around the substrate and the substrate is not rotatable.
19. The apparatus of claim 18, further comprising a motor that is
controllable to move the shutter and change the amount of target
material being blocked and the location of the target material on
the substrate being blocked.
20. The apparatus of claim 19, wherein the shutter is movable, such
that a gradient profile is generated during the deposition of the
target material on the substrate.
21. The apparatus of claim 19, wherein the shutter is moveable at a
constant speed.
22. The apparatus of claim 19, wherein the shutter is moveable at a
variable speed.
23. The apparatus of claim 19, wherein the shutter is adapted to be
initially positioned to block the target material at the center of
the substrate and is further adapted to move toward the edge of the
substrate while the shutter is rotated during deposition to
generate a conical profile.
24. The apparatus of claim 19, wherein the shutter is adapted to be
initially positioned to block the target material at the edge of
the substrate and is further adapted to move toward the rotation
center of the substrate during deposition while the shutter is
rotated.
25. The apparatus of claim 18 wherein the shutter is a first
shutter, and further comprising a second shutter that is
independently movable relative to the first shutter.
26. The apparatus of claim 25, wherein the first and second
shutters are adapted to be initially positioned at opposite edges
of the substrate and are further adapted to move toward each other
and toward the center of the substrate during deposition.
27. The apparatus of claim 25, wherein the first and second
shutters are adapted to be initially positioned at the center of
the substrate and are further adapted to move away from each other
and toward the opposite edges of the substrate during
deposition.
28. The apparatus of claim 25, wherein the first and second
shutters are adapted to be placed at a fixed position during the
deposition to generate an annular ring of target material on the
substrate.
29. The apparatus of claim 25, wherein the first and second
shutters are rotatable during the deposition to generate an annular
ring of target material on the substrate.
30-63. canceled.
64. A radial gradient deposition apparatus comprising: a rotatable
platform that is adapted to rotate a substrate during deposition; a
deposition source that is adapted to direct a target material for
deposition on the substrate; and a shutter that is adapted to
selectively blocks a varying amount of the target material during
deposition to generate a radial thickness gradient on the
substrate.
65. An apparatus for creating a radial profile of a target material
on a substrate the apparatus comprising: a deposition source for
directing a target material for deposition on a substrate; and a
shutter adapted to blocks an amount of the target material from
striking the substrate, the shutter being rotatable radially around
the substrate during the deposition of the target material to
generate a radial profile on the substrate.
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 119 and 120
from U.S. Provisional Patent Application Ser. No. 60/334.889, filed
on Nov. 15, 2001 and entitled "Method and Apparatus for Creating
Radial Symmetric Thickness and/or Composition Profiles on a
Substrate" and is also a continuation in part of U.S. patent
application Ser. No. 09/237,502, filed Jan. 29, 1999 and entitled
"Programmable Flux Gradient Apparatus For Co-Deposition Of
Materials Onto A Substrate".
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to a system and method for
depositing a target material on a substrate and in particular to a
system and method for depositing a target material having a radial
profile onto a substrate.
[0003] It is desirable to place radial thickness or composition
profiles and/or gradients of target materials onto a substrate. A
radial thickness profile or gradient is an amount of material being
deposited in a radial manner (to form, for example, an annular ring
around the substrate) onto the substrate. The thickness of that
target material can be varied along the radius of the substrate to
form the radial thickness gradients or other profiles of material.
In prior systems, a particular portion of material is deposited
onto a first portion of the substrate. Then, the substrate may be
rotated to a second position and another particular portion of
material is deposited onto the substrate with the substrate in the
second position. Then the substrate may be rotated to a third
position and the same process is repeated. In this manner,
thickness gradients may be generated, but the gradients or other
profiles are oriented with respect to specific directions on the
substrate, such as along the legs of a triangle for a ternary
system. Xiang, "Combinatorial Materials Synthesis and Screening: An
Integrated Materials Chip Approach to Discovery and Optimization of
Functional Materials", Ann. Rev. Mater. Sci. 1999, pgs. 149-171
(1999).
[0004] Thus, it is desirable to provide a method and apparatus for
creating radial thickness or composition gradients or other radial
symmetric profiles on a substrate that eliminates the above
limitations with the conventional system and it is to this end that
the present invention is directed.
SUMMARY OF THE INVENTION
[0005] The method and apparatus in accordance with the invention
permits a radial thickness and/or composition gradient or other
radial profile (including symmetric and asymmetric profiles) on a
substrate to be formed wherein the gradients or profiles are not
oriented in specific directions as is done with the prior systems.
To accomplish the above, the system comprises one or more dynamic
shutters (e.g., shutters that can be moved independently of each
other and during the deposition of a material) in combination with
equipment that permits rotation of the substrate relative to the
shutter(s), or rotation of the shutter(s) relative to the
substrate, during the deposition of the material onto the
substrate. The equipment may also stop/start, continuously rotate
at a constant speed or rotate the substrate at a variable speed
during the deposition of the material to generate various different
radial thickness or composition gradients or other arbitrary but
radial profiles on the substrate (including symmetric and
asymmetric profiles.) The system may also include one or more
contact masks that may be placed on the substrate during the
deposition in order to mask off particular portions of the
substrate during the deposition process. The system may also
include one or more deposition sources to perform deposition of
substances. With multiple deposition sources, each source and
shutter generates its own independent radial gradient or other
arbitrary radial profile, such as a symmetric or asymmetric
profiles. For convenience, the system is described in the context
of rotation of the substrate, relative to non-rotating shutters.
However, one skilled in the art will recognize that an equivalent
system could be implemented, in which the substrate is fixed, and
the dynamic shutter(s) are rotated around the substrate (as well as
moved according to their other capabilities as described
herein).
[0006] In accordance with the invention, the system causes a
rotation of the substrate relative to the shutter(s) (e.g., the
substrate is rotated and the shutter(s) are stationary or the
shutter(s) rotate and the substrate is stationary) during
deposition in order to induce a radial component into the thickness
composition profile or composition gradient. For example, the
substrate may be rotated sufficiently quickly, relative to the
deposition rate, to create thickness profiles that are conical
(e.g., low at the edges and higher in the middle of the substrate),
reverse conical (e.g., low at the middle of the substrate and high
at the edges of the substrate), concave, convex or any other radial
profiles. The radial deposited component may be symmetric or
asymmetric.
[0007] The parameters of the system in accordance with the
invention may be varied in order to change the profiles being
generated by the system. For example, the shutter shapes, the
shutter positions, the shutter motion profiles, the substrate
rotation speed and the substrate rotation centricity (whether or
not the substrate is rotated about its center) can all be
independently controlled and adjusted to generate various profiles,
such as continuous gradients of discrete compositional regions or
other desired film thickness profiles across the substrate.
[0008] In accordance with the invention, an apparatus for creating
a radial profile of a target material on a substrate is provided.
The apparatus comprises a deposition source for directing a target
material toward a substrate and a shutter that blocks an amount of
the target material from striking the substrate. The apparatus
further comprises a rotatable platform that induces rotation of the
substrate relative to the shutter system during the deposition of
the target material and the shutter blocks a predetermined amount
of the target material to generate a radial profile.
[0009] In accordance with another aspect of the invention, a method
for deposition of a radial profile of a target material onto a
substrate is provided. The method comprises directing target
material toward a substrate, blocking some predetermined portion of
the target material so that it does not strike the substrate, and
rotating the substrate while the target material is directed toward
the substrate so that a radial profile is formed on the substrate.
In accordance with yet another aspect of the invention, a substrate
comprises a target material formed on top of the substrate, the
target material having a radial profile wherein the radial profile
of the target material on the substrate is formed using at least
one shutter that blocks a predetermined amount of target material
while the substrate is being rotated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a diagram illustrating an example of a radial
profile deposition apparatus in accordance with the invention;
[0011] FIG. 2 is a diagram illustrating an example of the operation
of the radial profile deposition apparatus in accordance with the
invention;
[0012] FIG. 3 illustrates an example of the slope of a gradient
being generated by the operation of the apparatus shown in FIG.
1;
[0013] FIG. 4A illustrates another example of a gradient being
generated by the operation of the apparatus shown in FIG. 1;
[0014] FIGS. 4B-4E illustrate the positions of the shutter relative
to the substrate to generate the gradient shown in FIG. 4A;
[0015] FIG. 5 illustrates an example of a gradient profile from the
center of rotation to one edge of substrate (e.g., half of the
substrate) being generated by the apparatus shown in FIG. 1 when
the shutter starts at the edge, moves toward the center, and does
not reach the center of the substrate;
[0016] FIG. 6 illustrates an example of a gradient profile from the
center of rotation to one edge of substrate (e.g., half of the
substrate) being generated by the apparatus shown in FIG. 1 when
the shutter starts at the center, moves toward the edge, and does
not reach the edge of the substrate;
[0017] FIG. 7 illustrates an example of a gradient profile from the
center of rotation to one edge of substrate (e.g., half of the
substrate) being generated by the apparatus shown in FIG. 1 when
the shutter does not start from the center and does not reach the
edge of the substrate;
[0018] FIG. 8 illustrates an example of a gradient profile across
the entire substrate being generated by the apparatus shown in FIG.
1 when the shutter starts at the edge, moves toward the center, and
does not reach the center of the substrate;
[0019] FIG. 9 is a diagram illustrating another example of the
operation of the radial profile deposition apparatus in accordance
with the invention;
[0020] FIG. 10 illustrates a gradient profile with linear slope
from the center of rotation to one edge of substrate (e.g., half of
the substrate) generated by the example shown in FIG. 9 when the
shutter starts from full blocking position and reaches the rotation
center of the substrate;
[0021] FIG. 11 illustrates the cross-sectional view of the gradient
profile across the entire substrate generated by the example shown
in FIG. 9 in accordance with operation of FIG. 10;
[0022] FIG. 12 illustrates a gradient profile from the center of
rotation to one edge of substrate (e.g., half of the substrate)
generated by the example shown in FIG. 9 when the shutter starts at
the edge (full blocking of the substrate), but does not reach the
center of the substrate;
[0023] FIG. 13 illustrates a gradient profile from the center of
rotation to one edge of substrate (e.g., half of the substrate)
generated by the example shown in FIG. 9 when the shutter starts at
the center but does not reach the edge of the substrate;
[0024] FIG. 14 illustrates a gradient profile from the center of
rotation to one edge of substrate (e.g., half of the substrate)
generated by the example shown in FIG. 9 when the shutter moves
between the edge and center of the substrate;
[0025] FIG. 15 illustrates a gradient profile across the entire
substrate generated by the example shown in FIG. 9;
[0026] FIG. 16A illustrates a two shutter embodiment of the
apparatus that can also be used to generate the gradient shown in
FIG. 15;
[0027] FIG. 16B illustrates an example of a profile across the
entire substrate that may be generated using the apparatus shown in
FIG. 16A;
[0028] FIG. 17 is a diagram illustrating an annular ring that may
be generated using the deposition apparatus;
[0029] FIG. 18 illustrates a multiple target material source
embodiment in accordance with the invention; and
[0030] FIG. 19 illustrates another embodiment of the invention in
which the shutter rotates.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0031] The invention is particularly applicable to depositing a
material onto a semiconductor wafer and it is in this context that
the invention will be described. It will be appreciated, however,
that the apparatus and method in accordance with the invention has
greater utility since it can be used to deposit any type of
material onto any type of substrate in which radial thickness or
composition gradients or other arbitrary radial profiles are
desirable. Prior to describing the invention, a glossary of terms
being used in this application will be provided.
Glossary
[0032] The following terms are intended to have the following
general meanings as they are used herein.
[0033] 1. Substrate: A substrate is a material having a rigid or
semi-rigid surface, with respect to the nature of the deposited
material during deposition. In many embodiments, at least one
surface of the substrate will be substantially flat, although in
some embodiments it may be desirable to physically separate
synthesis regions for different materials with, for example,
dimples, wells, raised portions, etched trenches or the like. In
some embodiments, the substrate itself may contain wells, raised
regions, etched trenches, etc. which form all or part of the
synthesis regions. The substrate may typically have a surface area
of about 1 to 400 cm.sup.2 and usually between 6 to 100 cm.sup.2.
However, it should be understood that the substrate may be
substantially smaller or larger than the ranges depending on the
particular application. For example, the substrate may have a
surface area as small as about 0.1 to 1 cm.sup.2 or as large as
about 1 to 100 m.sup.2. The substrate can be made of a convenient
material depending on the components being deposited. For example,
the substrate material may be a solid-state compound, an extended
solid, an extended solution, a cluster of molecules or atoms, a
crystal, etc. as described more fully in U.S. Pat. No. 5,776,359
which is incorporated herein by reference.
[0034] 2. Target Material Source: A target material source is a
piece of equipment which expels a target material from a target in
order to direct the target material toward the substrate. The
target material source may expel the target material from the
target using a variety of different well known deposition
techniques, such as thermal evaporation techniques, sputtering
techniques, spraying techniques, laser deposition techniques, ion
beam deposition, ion implantation or doping technique as well as
other techniques used in the fabrication of integrated circuits and
epitaxially grown materials, and preferable with line-of-sight
techniques, such as thermal evaporation, electron beam deposition
and low pressure sputtering.
[0035] 3. Component: The term "component" may refer to each of the
individual chemical substances that are deposited onto a substrate.
The components may act upon one another to produce a particular
material. The components may also react with each other, or be
acted upon by a third material, chemical substance or energy
source. A component may be an element from the periodic table, a
chemical, a material, a mixture of elements or chemicals, etc. in
variable stoichiometries. The components may react directly with
each other or with an external source, or alternatively, they may
form layers, blends, mixtures or combinations thereof.
[0036] 4. Target Material: The term "target material" refers to
material which can be composed of elements, compounds, chemicals,
molecules, etc. that is vaporized, evaporated, boiled, sublimed,
ablated, sprayed, etc. from the exit of a container or holder so
that the target material may condense or otherwise deposit onto a
substrate during the synthesis process. Generally, a component, as
described above, is the set of individual chemical substances that
are expelled from the target material to be deposited onto the
substrate and the component may have the same composition as the
target material or it may comprise a portion of the target
material.
[0037] 5. Mixture or Blend: The term "mixture" or "blend" may refer
to a collection of molecules, ions, chemical substances, etc. The
amount of each component in the mixture may be independently
varied. A mixture may consist of two or more substances
intermingled with no constant percentage composition wherein each
component may or may not retain its essential original properties
and molecular phase mixing may or may not occur. In the mixture,
the components making up the mixture may or may not remain
distinguishable from each other by virtue of their chemical
structure.
[0038] 6. Shutter: The term "shutter" may refer to a mechanism for
blocking target material emitted by a target material source from
being deposited onto the substrate. Typically, the shutter may be
located in between the target material source and the substrate. In
preferred embodiments, the shutter may be a plate associated with
each target material source which may be moved relative to the
target material being deposited onto the substrate in order to
programmably block some predetermined portion of the target
material at predetermined times. The shutter may be used to form
composition profiles and/or gradients of target materials on the
substrate. The system of shutters and associated mechanisms for
moving the shutters for all of the target material sources may be
referred to as a "shutter system".
[0039] 7. Gradient: The term "gradient" refers to the fact that the
amount of target material deposited on the substrate by the target
material source may vary monotonically across some/all of the
substrate. The relationship between the particular amounts of
target material deposited may vary to provide a variety of
different gradients, such as, for example, a sloped gradient, a dam
shaped gradient or a stepped gradient.
[0040] FIG. 1 is a diagram illustrating an example of a radial
profile deposition apparatus 20 in accordance with the invention.
The apparatus is able to generate various different radial profiles
including radial fixed thickness profiles, mixtures of one or more
target materials, linear gradients, non-linear gradients, symmetric
profiles and asymmetric profiles. The apparatus 20 may include a
shutter system 22 including one or more dynamic and independently
movable and controllable shutters (one is shown in this example), a
target material source 24, such as a physical vapor deposition
(PVD) source or any other well known deposition source, that
generates the deposition target material, a rotating platform 26 on
which a substrate 28 is attached so that target material from the
deposition source may be deposited onto the substrate in various
radial profiles. The apparatus may further include a contact mask
30 that may be placed onto a portion of the substrate to block the
deposition target material during the entire deposition process.
The contact mask is shown in phantom since the contact mask may be
moved around as needed or removed from the substrate depending on
the desired profile. The contact mask 30 rotates with the
substrate.
[0041] In more detail, the rotating platform 26 may further include
a base portion 32 onto which the substrate is secured by any
conventional means, a typical motor 34 and a shaft 36 connected
between the motor and the base portion 32 in order to rotate the
rotating platform. The speed and velocity of the rotation of the
rotating platform may be precisely controlled (and optionally
varied during the deposition process) to achieve particular
profiles. The shutter system 22 may further include a shutter 38
that blocks the deposition material from contacting the substrate,
a motorized linear drive system 40 and a shaft 42 connecting the
drive system to the shutter so that each shutter may be
independently moved and positioned or its speed is controlled in
order to generate different profiles. In one embodiment, the drive
system may be controlled by a computer to provide programmable
shutter control. The same computer also may control the rotation of
the substrate.
[0042] In accordance with the invention, the profiles generated on
the substrate also are altered by changing the shape of each
shutter, the speed and/or velocity profile of the shutter and/or
the positions in which the shutter is placed during the deposition
process and/or the velocity profile of the substrate rotation
and/or the rate of deposition of the target material onto the
substrate. Using the above apparatus, radial thickness or
composition gradients or mixtures of target materials of a variety
of profiles and essentially any arbitrary radial profile may be
generated by controllably rotating the substrate and controlling
the shutter system during the deposition. The apparatus is capable
of generating a variety of different gradients and profiles since
the shutter shapes, the shutter positions, the shutter motion
profiles, the substrate rotation speed and the substrate rotation
centricity (whether or not the substrate is rotated about its
center) can all be independently controlled and adjusted to
generate either continuous or discrete profiles of discrete
compositional regions or other desired film thickness or
composition profiles across the substrate.
[0043] As an example of a profile that may be generated, in FIG. 2
the substrate is mounted on the rotating platform so that the
substrate rotates about its center and the single shutter may block
1/2 of the substrate initially. Then, the substrate is rotated
during the deposition and the shutter is moved toward the edge of
the substrate during the deposition. The movement of the shutter to
expose more of the substrate during the deposition creates a
conical gradient profile while moving the shutter to expose less of
the substrate during deposition results in a gradient profile that
is reverse conical (e.g., high at the edges of the substrate and
lower in the center of the substrate.) Now, examples of the
operation of the apparatus will be described.
[0044] FIG. 2 is a diagram illustrating an example of the operation
of the radial profile deposition apparatus in accordance with the
invention. In this example, the substrate is rotatable about its
center and is rotated during deposition, a single dynamic shutter
38 controlled by a computer is used and the target material
deposition source (not shown) is capable of depositing uniformly to
the entire substrate 28. In this example, the shutter moves at a
constant velocity in a linear motion and the deposition begins when
the shutter is at the edge of the substrate or beyond (and does not
block the substrate) and stops when the shutter reaches the
rotation center of the substrate. In this example, the film
thickness slope is linear (as illustrated in FIG. 3) and the
thickest point is at substrate rotation center. An example of the
profile generated using this example is shown in FIG. 4A. If
deposition starts when the edge of shutter is at the rotation
center and stops when the shutter reaches or goes beyond the right
edge of the substrate, the same pattern is created. Therefore, if
the shutter is oscillating between the center of the substrate
rotation and a point at or beyond the substrate edge, the same
pattern, i.e., a mountain shape with linear slope, is generated as
shown in FIG. 4A. FIGS. 4B-4E illustrate the motion of the shutter
relative to the substrate at different times (t.sub.1, t.sub.2,
t.sub.3 and t.sub.4) so that the mountain profile shown in FIG. 4A
is generated. Now, another example of the operation of the
apparatus will be described.
[0045] In this example of the operation of the apparatus, the
shutter moves at a constant velocity and in a linear motion and the
deposition begins when the shutter is within or at the substrate
edge and stops before or at the moment the shutter reaches the
substrate rotation center. The resultant film thickness slope is
generally non-linear (as shown in FIGS. 5-7), but the thickest
portion of the gradient profile is still at the center as shown in
FIG. 8. In other words, the pattern or profile is a monotonically
decaying curve. As in the example above, the reverse of the motions
(e.g., starting at the center and stopping at the edge of the
substrate) does not alter the character of the pattern. Therefore,
oscillatory motion will also not alter the profile. In FIG. 5, the
shutter starts at the edge of the substrate, but does not reach the
center. In FIG. 6, the shutter starts at the center of the
substrate, but does not reach the edge and in FIG. 7 the shutter
moves between the center and edge of the substrate in an
oscillatory motion. In accordance with the invention, to obtain a
linear slope, the velocity profile of the shutter should generally
be non-linear. This is also true for desired non-linear slope of
thickness or composition profile. Obviously, the shutter is
controlled by computer program hence almost any arbitrary profile
can be created, as long as it is monotonically descending from
rotation center to edge in this example. Now, another example of
the operation of the apparatus will be described.
[0046] FIG. 9 is a diagram illustrating an example of the operation
of the radial profile deposition apparatus in accordance with the
invention. In this example, the shutter moves at a constant
velocity (linear motion) and the deposition begins when the shutter
is at or beyond the left edge of substrate and stops when the
shutter reaches the center of the substrate rotation. The film
thickness slope is linear (as shown in FIG. 10) and the thickest
portion of the gradient profile is at substrate edge as shown in
FIG. 11. The reverse of motion does not alter the pattern, nor does
the oscillatory motion as above. Now, another example of the
operation of the apparatus will be provided.
[0047] FIG. 12 illustrates the slope of the gradient generated by
the example shown in FIG. 9 when the shutter starts at the edge,
but does not reach the center of the substrate. In this example,
the shutter moves at a constant velocity (linear motion) and the
deposition begins when the shutter is at the substrate left edge
and stops before the shutter reaches the substrate rotation center
(from left, as in the picture). In this example, the film thickness
slope is generally non-linear (as shown in FIG. 12) while the
thickest portion of the gradient profile is still at the edge of
the substrate as shown in FIG. 15. In other words, the pattern or
profile is a valley shape with monotonically ascending curve. As in
case 3, the reverse of the motion does not alter the character of
the pattern. Therefore, oscillatory motion will also not alter the
profile. FIG. 13 illustrates the slope of the gradient as
deposition begins when the shutter is at the substrate rotation
center but does not reach the substrate edge, and FIG. 14
illustrates the gradient slope when the shutter moves between the
rotation center and edge of the substrate. In accordance with the
invention, to obtain a linear slope, the velocity profile of the
shutter should generally be non-linear. This is also true for
desired non-linear slope of thickness or composition profile.
Obviously, the shutter is controlled by computer program hence
almost any arbitrary profile can be created, as long as it is
monotonically ascending from rotation center to edge in this
example.
[0048] The above examples demonstrate that even the simplest
embodiment can create essentially any arbitrary profile as desired
by means of stacking various basic profiles together. However, the
more efficient way to generate arbitrary radial profiles, such as
the profile shown in FIG. 16B, is to use a pair of dynamic shutters
as shown in FIG. 16A. FIG. 16B illustrates an example of the
profile generated using the two shutter system. FIG. 17 illustrates
another setup that may generate the profile shown in FIG. 16B. When
the two shutters are used during the deposition, each one is
independently controlled by computer program, and one shutter is
moved outwards and the other shutter is moved inwards to create
essentially any desired thickness or composition profile having
radial symmetry.
[0049] In accordance with the invention, other parameters of the
radial profile deposition apparatus in accordance with the
invention may be adjusted. For example, the substrate may be
rotated off-center which will result in a different profile. In
addition, more complex rotation patterns may be used, such as two
or more simultaneous rotations about different axes of the
substrate during the deposition. Furthermore, the substrate may be
rotated through a predetermined angle less than one complete
rotation, such as 180.degree., to determine which different
tangential and radial points of the substrate receive the target
material or target materials. Thus, the angular start point of the
substrate, the rotation distance, the shutter velocity and position
may be adjusted to generate various different profiles.
Furthermore, the deposition rate (the rate at which the source
supplies target material to the substrate) may be modified during
the course of deposition, in a way that may or may not relate to
shutter(s) position. For the clarity of description, all the above
examples are given for a single source deposition. However, the
method also works using the simultaneous co-deposition of multiple
sources wherein each source has its own shutter system and creates
its own and independent radial thickness or composition
profile.
[0050] FIG. 18 illustrates a radial profile deposition source
apparatus 40 wherein there are two or more target material sources
24, 25 that each direct target material toward the substrate 28
that is being rotated by the rotation platform 26. In this
embodiment, there may be multiple shutter systems 22, 23 (one for
each target material source) so that each target material's profile
is independently controllable as described above. In this example
shown, two target material sources are shown and two shutter
systems are shown. In accordance with the invention, each target
material source may have multiple shutters associated with it so
that, for example, an annular ring of each target material may be
formed on the substrate. The co-deposition of materials generally
is described in more detail in co-pending U.S. patent application
Ser. No. 09/237,502 entitled "PROGRAMMABLE FLUX GRADIENT APPARATUS
FOR CO-DEPOSITION OF MATERIALS ONTO A SUBSTRATE" that was filed on
Jan. 26,1999. The disclosure of that patent application is
incorporated herein by reference. In such multiple sources
applications, a shutter is placed in between the substrate and the
deposition source it is associated with instead of the shutter
being placed substantially near the substrate in the single source
embodiment, so that the shutter will only block or pass material
from the associated source interacting with the substrate but shall
not block or affect any other sources interacting with the same
substrate. This is generally shown in the above patent application
that is incorporated herein by reference. Thus, during operation,
while multiple sources are depositing various substances onto the
substrate simultaneously, each substance is controlled individually
and independently via its associated deposition source and shutter
mechanism, as if it is single source deposition as described
earlier.
[0051] FIG. 19 illustrates another embodiment of the invention. In
this embodiment, the substrate 28 does not rotate while the shutter
system rotates. Although a single shutter system 22 is shown, there
may be multiple sources and multiple shutter systems to provide
multiple source deposition of materials onto the substrate.
Returning to FIG. 19, the substrate does not rotate and the shutter
system 22 and the shutter 38 in particular, is rotated around the
substrate as shown to produce the same radial thickness or
composition gradients or other arbitrary radial profiles as may be
generated by the other embodiments described above. In other words,
this embodiment is also capable of generating the profiles shown
and described above since one element of the deposition system is
being rotated relative to the other elements of the deposition
system which achieves the desired radial profiles and/or
gradients.
[0052] While the foregoing has been with reference to a particular
embodiment of the invention, it will be appreciated by those
skilled in the art that changes in this embodiment may be made
without departing from the principles and spirit of the invention,
the scope of which is defined by the appended claims.
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