U.S. patent application number 11/054003 was filed with the patent office on 2005-08-04 for combinatorial synthesis of material chips.
This patent application is currently assigned to Intematix Corporation. Invention is credited to Li, Yi-Qun.
Application Number | 20050166850 11/054003 |
Document ID | / |
Family ID | 24264721 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050166850 |
Kind Code |
A1 |
Li, Yi-Qun |
August 4, 2005 |
Combinatorial synthesis of material chips
Abstract
Systems and methods for providing in situ, controllably variable
concentrations of one, two or more chemical components on a
substrate to produce an integrated materials chip. The component
concentrations can vary linearly, quadratically or according to any
other reasonable power law with one or two location coordinates. In
one embodiment, a source and a mask with fixed or varying aperture
widths and fixed or varying aperture spacings are used to produce
the desired concentration envelope. In another embodiment, a mask
with one or more movable apertures or openings provides a chemical
component flux that varies with location on the substrate, in one
or two dimensions. In another embodiment, flow of the chemical
components through nuzzle slits provides the desired
concentrations. An ion beam source, a sputtering source, a laser
ablation source, a molecular beam source, a chemical vapor
deposition source and/or an evaporative source can provide the
chemical component(s) to be deposited on the substrate. Carbides,
nitrides, oxides, halides and other elements and compounds can be
added to and reacted with the deposits on the substrate.
Inventors: |
Li, Yi-Qun; (Orinda,
CA) |
Correspondence
Address: |
QUINE INTELLECTUAL PROPERTY LAW GROUP, P.C.
P O BOX 458
ALAMEDA
CA
94501
US
|
Assignee: |
Intematix Corporation
|
Family ID: |
24264721 |
Appl. No.: |
11/054003 |
Filed: |
February 8, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11054003 |
Feb 8, 2005 |
|
|
|
09566866 |
May 8, 2000 |
|
|
|
Current U.S.
Class: |
118/730 ;
118/696; 204/192.1 |
Current CPC
Class: |
B01J 2219/0043 20130101;
B01J 2219/00445 20130101; B01J 2219/00527 20130101; B01J 2219/00752
20130101; B01J 19/0046 20130101; C23C 16/45563 20130101; B01J
2219/00605 20130101; C23C 16/04 20130101; B01J 2219/00754 20130101;
C40B 60/14 20130101; C40B 40/18 20130101; B01J 2219/00659 20130101;
C23C 14/044 20130101; B05D 1/32 20130101; B01J 2219/00585 20130101;
C23C 14/042 20130101; C23C 16/042 20130101; B01J 2219/0059
20130101; B01J 2219/00756 20130101; B01J 2219/0075 20130101; B01J
2219/00441 20130101; B01J 2219/00592 20130101; B01J 2219/00745
20130101; B05D 1/60 20130101; B01J 2219/00443 20130101; B05D 1/34
20130101 |
Class at
Publication: |
118/730 ;
118/696; 204/192.1 |
International
Class: |
C23C 014/00; C23C
014/32; H01L 021/44; C23C 016/00; B05C 011/00 |
Claims
What is claimed is:
1. A system for depositing on a substrate a mixture of selected
first and second chemical components having concentrations of the
first and second components that vary controllably with a location
coordinate measured along a surface of the substrate, the system
comprising: first and second sources of respective first and second
chemical components, spaced apart from the substrate, with the
first source and the second source providing first and second
fluxes, respectively, of the first and second components; a mask,
having a first end and a second end and being positioned between
the substrate and the first and second sources, that is movable in
a direction transverse to at least one of a first line of sight
extending from the first source to the substrate and a second line
of sight extending from the second source to the substrate; and a
motor that moves the mask, from a first location, in which at least
a portion of the substrate is visible from the first source, to a
second location in which the substrate is not visible from the
first source and that moves the mask, from a third location, in
which the substrate is not visible from the second source, to a
fourth location in which at least a portion of the substrate is
visible from the second source.
2. The system of claim 1, wherein said first and second sources are
positioned relative to said substrate so that, when said mask is
located at a selected fifth location, no portion of said substrate
is visible from said first source and no portion of said substrate
is visible from said second source.
3. The system of claim 1, wherein at least one of said first
source, said second source, said mask and said motor is configured
to provide a mixture of said chemical components on said substrate
surface in which said concentration of at least one of said first
chemical component and said second chemical component varies
linearly with a location coordinate measured along said substrate
surface.
4. The system of claim 1 wherein at least one of said first source,
said second source, said mask and said motor is configured to
provide a mixture of said chemical components on said substrate
surface in which said concentration of at least one of said first
chemical component and said second chemical component varies
nonlinearly with a location coordinate measured along said
substrate surface.
5. The system of claim 1, wherein at least one of said first source
and said second source is configured to provide a corresponding
chemical component flux that varies with time according to a
selected function of time.
6. The system of claim 1, wherein said motor moves said mask at a
uniform rate with respect to time in said direction transverse to
at least one of said first line of sight and said second line of
sight.
7. The system of claim 1, wherein said motor moves said mask at a
non-uniform rate with respect to time in said direction transverse
to at least one of said first line of sight and said second line of
sight.
8. The system of claim 1, wherein at least one of said first source
and said second source is drawn from a group of chemical component
sources consisting of an ion beam sputtering source, a sputtering
source, a laser ablating source, a molecular beam source, a
chemical vapor deposition source and an evaporative source.
9. The system of claim 1, wherein at least one of said first and
second chemical components includes at least one chemical element
drawn from a group of chemical elements consisting of lithium,
sodium, potassium, rubidium, cesium, berkelium, magnesium, calcium,
strontium, barium, boron, aluminum, gallium, carbon, silicon,
germanium, nitrogen, phosphorous, arsenic, oxygen, sulfur,
selenium, tellurium, fluorine, chlorine, bromine and iodine.
10. A system for depositing on a substrate a mixture of selected
first and second chemical components having concentrations of the
first and second components that vary controllably with a location
coordinate measured along a surface of the substrate, the system
comprising: first and second sources of respective first and second
chemical components, spaced apart from the substrate, with the
first source and the second source providing first and second
fluxes, respectively, of the first and second components; a mask,
having at least one aperture with an aperture width and being
positioned between the substrate and the first and second sources,
that is movable in a direction transverse to at least one of a
first line of sight extending from the first source to the
substrate and a second line of sight extending from the second
source to the substrate; and a motor that moves the aperture
location, from a first location in which at least a portion of the
substrate is visible through the aperture from the first source, to
a second location in which at least a portion of the substrate is
visible through the aperture from the second source.
11. The system of claim 10, wherein said aperture width for said at
least one aperture is fixed at a selected value.
12. The system of claim 10, wherein said aperture width for said at
least one aperture varies with time in a selected manner.
13. The system of claim 10, wherein at least one of said first
source, said second source, said mask and said motor is configured
to provide a mixture of said chemical components on said substrate
surface in which said concentration of at least one of said first
chemical component and said second chemical component varies
linearly with a location coordinate measured along said substrate
surface.
14. The system of claim 10, wherein at least one of said first
source, said second source, said mask and said motor is configured
to provide a mixture of said chemical components on said substrate
surface in which said concentration of at least one of said first
chemical component and said second chemical component varies
nonlinearly with a location coordinate measured along said
substrate surface.
15. The system of claim 10, wherein at least one of said first
source and said second source is configured to provide a
corresponding chemical component flux that varies with time
according to a selected function of time.
16. The system of claim 10, wherein said motor moves said mask at a
uniform rate with respect to time in said direction transverse to
at least one of said first line of sight and said second line of
sight.
17. The system of claim 10, wherein at least one of said first
source and said second source is drawn from a group of chemical
component sources consisting of an ion beam sputtering source, a
sputtering source, a laser ablating source, a molecular beam
source, a chemical vapor deposition source and an evaporative
source.
18. The system of claim 10, wherein at least one of said first and
second chemical components includes at least one chemical element
drawn from a group of chemical elements consisting of lithium,
sodium, potassium, rubidium, cesium, berkelium, magnesium, calcium,
strontium, barium, boron, aluminum, gallium, carbon, silicon,
germanium, nitrogen, phosphorous, arsenic, oxygen, sulfur,
selenium, tellurium, fluorine, chlorine, bromine and iodine.
19. A system for depositing on a substrate a mixture of selected
first and second chemical components having concentrations of the
first and second components that vary controllably with a location
coordinate measured along a surface of the substrate, the system
comprising: first and second sources of the respective first and
second chemical components, spaced apart from the substrate, with
the first source and the second source providing first and second
fluxes, respectively, of the first and second components; first and
second nuzzle slits, associated with the first and second sources,
respectively, that direct the first and second fluxes of the first
and second components toward the substrate in selected first and
second flux patterns, respectively, in a selected coordinate
direction.
20. The system of claim 19, wherein said first nuzzle slit directs
said first flux in said first pattern in said first coordinate
direction and in a selected third pattern in a selected second
coordinate direction.
21. The system of claim 19, wherein said first and second nuzzle
slits direct said first flux and second fluxes in said first and
second flux patterns, respectively, and in selected third and
fourth patterns, respectively, in a selected second coordinate
direction.
22. The system of claim 19, wherein at least one of said first
source and said second source is drawn from a group of sources
consisting of an ion beam sputtering source and a chemical vapor
deposition source.
23. The system of claim 19, wherein at least one of said first and
second chemical components includes at least one chemical element
drawn from a group of chemical elements consisting of lithium,
sodium, potassium, rubidium, cesium, berkelium, magnesium, calcium,
strontium, barium, boron, aluminum, gallium, carbon, silicon,
germanium, nitrogen, phosphorous, arsenic, oxygen, sulfur,
selenium, tellurium, fluorine, chlorine, bromine and iodine.
24. A system for depositing on a substrate a selected chemical
component having a concentration that varies controllably with a
location coordinate measured along a surface of the substrate, the
system comprising: a source of a selected chemical component,
spaced apart from the substrate by a selected distance, s1+s2,
where the source provides a chemical component flux in a flux
direction extending from the source toward the substrate; a mask,
positioned between the source and the substrate at a selected
distance s1 from the source, having two or more apertures with
selected aperture widths and selected aperture spacings in a
coordinate direction x that is transverse to the flux direction,
where the aperture widths and the aperture spacings are selected so
that a concentration envelope C(x), representing the concentration
of the chemical component deposited on the substrate as a function
of the coordinate x, is substantially equal to a selected function
f(x).
25. The system of claim 24, wherein said function f(x) is drawn
from the group of functions consisting of:
f(x)=a+b.multidot.x,f(x)=a+b.vertline.x- .vertline. and
f(x)=a'+b'.multidot.(x)q, where a, b, a', b' and q are selected
real numbers.
26. The system of claim 24, wherein said source is drawn from a
group of chemical component sources consisting of an ion beam
sputtering source, a sputtering source, a laser ablating source, a
molecular beam source, a chemical vapor deposition source and an
evaporative source.
27. The system of claim 24, wherein at least one of said first and
second chemical components includes at least one chemical element
drawn from a group of chemical elements consisting of lithium,
sodium, potassium, rubidium, cesium, berkelium, magnesium, calcium,
strontium, barium, boron, aluminum, gallium, carbon, silicon,
germanium, nitrogen, phosphorous, arsenic, oxygen, sulfur,
selenium, tellurium, fluorine, chlorine, bromine and iodine.
28. A system for depositing on a substrate a selected chemical
component having a concentration that varies controllably with a
location coordinate measured along a surface of the substrate, the
system comprising: a target surface that includes selected
precursor particles; an ion beam source, directed at the target
surface, to provide a flux of precursor particles in response to
collision of the ion beam with the target surface; direction
control means for directing at least a portion of the precursor
particles flux toward a surface of a substrate; a mask, positioned
between the target surface and the substrate surface and having at
least one aperture of selected aperture shape and diameter that
permits at least a portion of the precursor particle flux to reach
at least a portion of the substrate surface, where the aperture
shape and diameter are selected to provide a selected non-uniform
distribution of precursor particles that are received by the
substrate surface.
29. The system of claim 28, wherein said source is configured to
provide a corresponding chemical component flux that varies with
time according to a selected function of time.
30. The system of claim 28, further comprising: a motor that moves
the mask, from a first location, in which at least a portion of the
substrate is visible from said source, to a second location in
which no portion of the substrate is visible from said source.
31. The system of claim 30, wherein at least one of said source,
said mask and said motor is configured to provide a mixture of said
chemical components on said substrate surface in which said
concentration of at least one of said first chemical component and
said second chemical component varies linearly with a location
coordinate measured along said substrate surface.
32. The system of claim 30, wherein at least one of said source,
said mask and said motor is configured to provide a mixture of said
chemical components on said substrate surface in which said
concentration of at least one of said first chemical component and
said second chemical component varies nonlinearly with a location
coordinate measured along said substrate surface.
33. The system of claim 30, wherein said motor moves said mask at a
uniform rate with respect to time in said direction transverse to
at least one of said first line of sight and said second line of
sight.
34. The system of claim 30, wherein said motor moves said mask at a
non-uniform rate with respect to time in said direction transverse
to at least one of said first line of sight and said second line of
sight.
35. The system of claim 28, further comprising: a source of a
selected compound, containing an element drawn from a group of
elements consisting of lithium, sodium, potassium, rubidium,
cesium, berkelium, magnesium, calcium, strontium, barium, boron,
aluminum, gallium, carbon, silicon, germanium, nitrogen,
phosphorous, arsenic, oxygen, sulfur, selenium, tellurium,
fluorine, chlorine, bromine and iodine, located adjacent to said
substrate, and particle means for producing particles of the
selected compound; and second direction control means for directing
at least a portion of the selected compound particles toward said
substrate surface.
36. A method for depositing on a substrate surface a mixture of
selected first and second chemical components having a relative
concentration of the first and second components that varies
controllably with a location coordinate, the method comprising:
directing first and second fluxes of first and second chemical
components, respectively, toward at least one surface of a
substrate; and providing a mask that allows a first selected
portion of the first chemical component flux to be deposited on the
substrate, that prevents a second selected portion of the first
chemical component flux from being deposited on the substrate, that
allows a first selected portion of the second chemical component
flux to be deposited on the substrate, and that prevents a second
selected portion of the second chemical component flux from being
deposited on the substrate, where the mask has at least one opening
that is chosen to allow deposit of at least one of the first and
second chemical components on the substrate according to a selected
variable concentration.
37. The method of claim 36, further comprising the step of moving
said mask at a selected movement rate in a direction that is
transverse to a selected line of sight that is approximately
parallel to at least one of said first chemical component flux and
said second chemical component flux.
38. The method of claim 37, further comprising configuring at least
one of said first source, said second source, said mask and said
mask movement rate to provide a mixture of said chemical components
on said substrate surface in which said concentration of at least
one of said first chemical component and said second chemical
component varies linearly with a location coordinate measured along
said substrate surface.
39. The method of claim 37, further comprising configuring at least
one of said first source, said second source, said mask and said
mask movement rate to provide a mixture of said chemical components
on said substrate surface in which said concentration of at least
one of said first chemical component and said second chemical
component varies nonlinearly with a location coordinate measured
along said substrate surface.
40. The method of claim 36, further comprising configuring at least
one of said first source and said second source to provide a
corresponding chemical component flux that varies with time
according to a selected function of time.
41. The method of claim 36, further comprising providing at least
one of said first chemical component and said second chemical
component from a group of chemical component sources consisting of
an ion beam sputtering source, a sputtering source, a laser
ablating source, a molecular beam source, a chemical vapor
deposition source and an evaporative source.
42. The method if claim 36, further comprising choosing at least
one of said first and second chemical components to include at
least one chemical element drawn from a group of chemical elements
consisting of lithium, sodium, potassium, rubidium, cesium,
berkelium, magnesium, calcium, strontium, barium, boron, aluminum,
gallium, carbon, silicon, germanium, nitrogen, phosphorous,
arsenic, oxygen, sulfur, selenium, tellurium, fluorine, chlorine,
bromine and iodine.
Description
FIELD OF THE INVENTION
[0001] This invention relates to methods and systems for deposition
of chemicals in controllably variable amounts on a substrate.
BACKGROUND OF THE INVENTION
[0002] In the past decade, several workers have applied a
combinatorial synthesis approach to development of new materials,
or to construction of known materials in new ways. Material chip
samples, with varying chemical compositions involving two or three
components and with discrete or continuous composition change, can,
in principle, be synthesized, using multilayers and masks. However,
a true multi-composition compound probably cannot be formed unless
each multilayer is formed and uniformly diffused at relatively low
temperatures. This appears to require an in situ approach, which is
not well understood and is not developed in the background art.
[0003] What is needed is an in situ approach and/or a multilayer
approach for formation of chemical compounds having two, three or
more components and having controllably variable composition on a
substrate. Preferably, the approach should be flexible and should
easily allow change of one or more geometric, physical and chemical
parameters describing the formation process and the variation of
composition with location on the substrate. Preferably, the
approach should allow a choice of the geometric variation (linear,
nonlinear, etc.) of one or more composition parameters according to
the intended use and environment of the material chip.
SUMMARY OF THE INVENTION
[0004] These needs are met by the invention, which provides several
systems and associated methods for controllably variable in situ or
multilayer deposition of two or more chemical components on a
substrate. In one embodiment, an ultra-high vacuum (UHV) ion beam
sputtering system or evaporation system includes a multi-target
carousel, a precision mask that is movable in one or two coordinate
directions, x and y, and a stepper motor to move the mask by
controllable amounts in the x- and/or y-directions in a timed
sequence. Pure metal sputtering or evaporation targets are used to
deposit precursors in selected layers. Use of a UHV environment
ensures that the precursor layers are not oxidized during or after
deposition. A heating element, built into or associated with a
sample holder, provides thermally-driven precursor diffusion after
the deposition, without exposing the sample to air during sample
transfer. Ion beam sputtering has several advantages: target
exchange is relatively simple; most metal targets are available;
and precursor interdiffusion occurs at much lower temperatures and
over shorter time intervals than are required for distribution of
metal-inorganic compounds. As a further benefit, where a second ion
gun is added to the assembly, oxides, nitrides, carbides, halogens
and similar substances can be formed in situ from the metal
precursor films.
[0005] A second embodiment involves a chemical vapor deposition
(CVD) approach and provides large area uniformity for the
deposition, the possibility of co-deposition of multi-component
thin films with individually controllable growth rates, and control
of growth of the profile.
[0006] Another embodiment uses a deposition system equipped with
two or more profile-controllable, precursor sources for in situ
generation of continuous phase diagrams. This embodiment uses
co-deposition with a nuzzle design to generate a linear or other
geometric deposition profile for each component deposited on the
substrate.
[0007] In another embodiment, a mask with variable center-to-center
aperture spacings and variable aperture sizes is used to deposit
each of two or more chemical components onto a substrate, with the
concentration of each chemical being variable independently with a
location coordinate x. The concentration may vary linearly with x
(preferable), as a power or combination of powers of x, or in some
other nonlinear manner with the coordinate x, and two or more
component concentrations may have qualitatively or quantitatively
different geometric variations with x. The concentration may also
vary independently in each of two location coordinate directions,
for example, with the Cartesian coordinates x and y or the polar
coordinates r and .theta..
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic view illustrating ion beam sputtering
deposition for combinatorial synthesis of a material.
[0009] FIG. 2 is a schematic view illustrating use of controlled
movement of a mask to generate a linear thickness profile for two
chemical components.
[0010] FIGS. 3A, 3B and 3C illustrate use of deposition and
interdiffusion to promote formation of metal-inorganic
compounds.
[0011] FIG. 4 is a schematic view illustrating use of CVD for
combinatorial synthesis of a material.
[0012] FIGS. 5A and 5B are graphical views of possible deposition
patterns generated using the apparatus of FIG. 4 or FIG. 6A.
[0013] FIGS. 6A and 6B are schematic views illustrating use of a
movable slot window or slit to control growth rate in a linear ramp
for in situ formation of a compound A.sub.uB.sub.1-u.
[0014] FIGS. 7A, 7B, 8 and 9 are schematic views illustrating use
of two or three nuzzles to generate a linear deposition profile for
in situ formation of a compound A.sub.uB.sub.1-u. or
A.sub.uB.sub.vC.sub.1-u-v.
[0015] FIGS. 10A/10B and 11A/11B are pairs including a schematic
view and a graphical view illustrating two embodiment of the
invention, using one and two sources, respectively.
[0016] FIGS. 12, 13 and 14 are schematic views of other
embodiments.
[0017] FIG. 15 is a flow chart illustrating practice of the
invention.
DESCRIPTION OF MODES OF THE INVENTION
[0018] FIG. 1 schematically illustrates an embodiment of the
invention that uses ion beam sputtering as part of a combinatorial
synthesis of a desired material. A substrate 11 is positioned
inside an ultra-high vacuum chamber 13, preferably having a
pressure level of 10.sup.-9 Torr or lower, using a cryogenic pump,
ion pump or other pump means (not shown) suitable for metal alloy
deposition. Preferably, a load-and-lock chamber 15 is provided to
facilitate sample exchange without breaking the vacuum of the main
chamber 13. A sputtering target 17 receives an ion beam 19,
provided by an ion source 21, and produces deposition or precursor
particles DP having a desired chemical composition. A portion of
the precursor particles DP is received at, and deposited on, an
exposed surface of the substrate 11. Growth rate of the deposited
layer on the substrate 11 can be controlled, within a high
precision range, by the power applied to the ion beam sputtering
source 21 and by the angular orientation of the target 17 to the
ion source and to the substrate 11. Real time control can be
implemented using real time monitoring of, and a negative feedback
loop to control, ion beam current.
[0019] Some advantages of an ion beam sputter approach are: (1)
inter-diffusion between metals occurs at lower temperatures and at
higher diffusion rates, in comparison with inter-diffusion of
metal-inorganic compounds, where temperatures above 1000.degree. C.
are often-required; (2) most metal targets are already available as
precursor sources; and (3) more than one ion beam, each with a
different precursor source material, can be provided in order to
form compounds including lithium, sodium, potassium, rubidium,
cesium, berkelium, magnesium, calcium, strontium, barium, boron,
aluminum, carbon, silicon, nitrogen, phosphorous, arsenic, oxygen,
sulfur, selenium, tellurium, fluorine, chlorine, bromine, iodines
and similar compounds following inter-diffusion of the deposited
constituents.
[0020] A carousel 25 holds and presents any one of a number N of
metal or similar targets 17 for an ion beam, to produce a stream 19
of precursor particles DP that are received by the substrate 11,
where N can be 1-50, or any other reasonable number. A second
reactive chemical source 27 is optionally located near the
substrate 11 and is oriented to provide a beam 29 of chemical
particles to act as a reactive agent for in situ formation of a
compound containing at least one different chemical element. After
precursor deposition and interdiffusion processes are carried out,
the precursors are reacted with each other and/or with any other
compounds containing elements from the lithium, berkelium, boron,
carbon, nitrogen, oxygen and/or fluoride columns of the Periodic
Table, or other similar compounds, to form the desired final
products.
[0021] The reactive chemical source 27 can be replaced or
supplemented by a source 28 of a low reactivity beam, such as Ne or
Ar particles, to etch the substrate or to enhance the energy
locally on the substrate, useful in creating high quality thin
films. Metal films have been prepared using a first ion gun for
target sputtering and a second ion gun for assisting controlled
growth of a thin film on a substrate. A movable mask 31 or sequence
of movable masks, controlled by a mask movement device 33, covers
different portions of the substrate surface at different times to
perform layer-by-layer precursor deposition. A heating element 35
(optional) loacted adjacent to the substrate 11, helps to perform
and control precursor interdiffusion after the initial
deposition.
[0022] As an alternative, to use of an ion beam to deposit
precursor particles DP on a substrate, the ion beam 21 may be
replaced by an irradiation unit 23 or by a high temperature
(T=600-1500.degree. C.) heating unit 24 that acts upon the target
17 to cause evaporation of precursor particles from the target
surface. A selected fraction of the evaporated particles DP are
then caused to travel toward and to deposit on the substrate 11 by
a particle direction control mechanism (not shown explicitly in
FIG. 1).
[0023] FIG. 2 schematically illustrates a deposition procedure for
combinatorially synthesizing an alloy, A.sub.uB.sub.1-u, on a
substrate 41 with the index u varying continuously or in small
increments between 0 and 1. A mask 43, which is movable from left
to right and/or from right to left by a mask stepper motor or other
suitable movement device 44, is located between the substrate 41
and one or more chemical component sources 45. The source 45
provides a flux of the chemical constituent A, or a flux of the
chemical constituent B. Each source 45 of a chemical constituent, A
or B, can be located at the same location, or two or more sources,
45 and 46, may be located at different locations relative to the
substrate 41. In a preferred approach, each source 45 is
sequentially moved into a beam focus position, and the ion beam or
other beam is activated to provide a stream of source particles
that preferably move in the general direction of the substrate
41.
[0024] In one approach, the mask 43 is moved from left to right and
only the first beam-activated source provides a (first) stream of
deposition particles in a first time interval. In a second time
interval, the second beam-activated source provides a (second)
stream of precursor particles. Because the first and second
particle streams are provided within different time intervals, this
approach produces a multilayer deposition on the substrate.
[0025] As the mask 43 moves from the left toward the right, the
portion LES of the substrate to the left of the left end LEM of the
mask 43 is exposed, for varying amounts of time, with portions of
the substrate 41 near the left end LES being exposed for longer
times than portions of the substrate near the right end RES of the
substrate. This produces a heavier deposit of precursor particles
at the left end LES of the substrate 41. The number of precursor
particles from the source 45 deposited per unit area decreases
monotonically as one moves from the left end LES toward the right
end RES of the substrate; and the number of precursor particles
deposited per unit area increases monotonically as one moves from
the left end LES to the right end RES of the substrate. If,
instead, the mask 43 moves from the right toward the left, the
number of precursor particles deposited on the substrate 41
decreases monotonically as one moves from the right end RES toward
the left end LES.
[0026] As a first alternative, the mask 43 can be held fixed and
the substrate 41 can be moved from left to right and/or from right
to left by a substrate stepper motor or similar movement device 44
to provide a multilayer deposition. As a second alternative, the
substrate 41 and the mask 43 can each be moved, independently and
at different rates, from left to right and/or from right to left to
provide a multilayer deposition.
[0027] Preferably, the mask length ML is at least equal to the
substrate length SL and the right end REM of the mask 43 begins at
a point above the left end LES of the substrate and moves rightward
monotonically until the left end LEM of the mask is above the right
end RES of the substrate. The amounts of time, .DELTA.t(x;A) and
.DELTA.t(x;B), that a particular location (x) on the substrate is
exposed to particle flux from a source 45 must be coordinated in
order to deposit appropriate relative amounts of the A and B
particles. If the mask length ML and the substrate length SL are
equal, the total amount of time
.DELTA.t(tot)=.DELTA.t(x;A)+.DELTA.t(x;B) (1)
[0028] any location (x) on the substrate is exposed will be the
same, no matter how the mask is moved from left (where REM and LES
correspond) to right (where LEM and RES correspond).
[0029] The mask may be moved at a linear rate, thus producing a
linearly varying alloy composition A.sub.u(x)B.sub.1-u(x), with
u(x)=a.multidot.x+b where x is a location coordinate, measured from
the left end LES of the substrate 41, and a and b are real numbers
related to the speed of movement of the mask from left to right.
Alternatively, the mask 43 may be moved at a non-constant rate from
left to right, and the chemical composition, u(x) versus 1-u(x), of
the alloy A.sub.u(x)B.sub.1-u(x) will vary nonlinearly as a
function of the location coordinate x. The composition u(x) versus
1-u(x) for the relative amounts of A and B components is determined
by a prescription such as
w(x)=.intg..chi.[x-s(t)]dt/.DELTA.t(tot), (2)
[0030] where s(t) (0.ltoreq.s(t).ltoreq.SL;
0.ltoreq.t.ltoreq..DELTA.t(tot- ) ) is the x coordinate of the
right end REM of the mask 43 at any time t, measured from the left
end of the substrate LES, .chi.(u) is a characteristic function
satisfying 1 ( u ) = 0 ( u < 0 ) = 1 ( u > 0 ) , ( 3 )
[0031] and the integral extends over the time interval
0.ltoreq.t.ltoreq..DELTA.t(tot).
[0032] FIGS. 3A, 3B and 3C illustrate deposition, interdiffusion
and chemical conversion processes. In FIG. 3A, the precursors DP
are incident on and received at the substrate 11, forming one or
more layers, optionally with a concentration gradient. In FIG. 3B,
the substrate 11 is subjected to interdiffusion and/or annealing of
the precursors DP deposited in FIG. 3A. This produces a further
redistribution of the precursors DP. In FIG. 3C, the interdiffused
precursors of FIG. 3B are combined with ion beam sputter-assisted
carbon, oxygen, nitrogen, carbon, halogen or other selected
compounds to provide carbidized, nitridized, oxidized, halogenated
or other desired compounds on the substrate 11, using the reactive
chemical source 27 of FIG. 1 or another source.
[0033] FIG. 4 schematically illustrates combinatorial synthesis of
a compound on a thermally controlled substrate 51 using chemical
vapor deposition (CVD) to provide in situ or multilayer deposition
for combinatorial synthesis. A carrier gas source 52 provides a
carrier gas (preferably inert) that is passed through a selected
number of one or more precursor evaporators or "bubblers", 53A, 53B
and 53C, that provide the active vapor substance(s), 54A, 54B and
54C, for CVD, either simultaneously or sequentially. Optionally,
the active vapors, 54A, 54B and 54C, pass through corresponding
flow controllers, 55A, 55B and 55C, that determine the active vapor
flow rates of the respective vapors at any given time. The active
vapors enter a pre-deposition chamber 56 and are moved axially
along the chamber by a push gas provided by a push gas source 57.
Flux f.sub.54S of the active vapor mix (S=A, B and/or C) is stopped
by, or is allowed to pass beyond, a movable mask or shutter or
aperture 58 whose transverse location, given by s=s(t), is
controlled by a mask stepper motor or other mask movement device 59
that moves the mask transversely (not necessarily perpendicularly),
relative to a line of sight extending from the source
(predeposition chamber 56) toward the substrate 51, across an
exposed surface of the substrate 51. As a first alternative, the
mask 58 is fixed in location and a substrate stepper motor or other
substrate movement device 59 moves the substrate 51 transversely.
As a second alternative, the mask movement device 59 and substrate
movement device 60 independently move the substrate 51 and the mask
58 transversely at the same time.
[0034] By separately controlling the precursor evaporators, 53A,
53B and 53C, and the corresponding flow controllers, 55A, 55B and
55C, the mix of active vapors 54S that issues from the
pre-deposition chamber 56 can be closely controlled as a function
of time. By controlling the mask location, x=s(t), the relative
amounts of the vapors 54S deposited on different regions of the
substrate 51 can be varied independently from point to point. For
example, the relative fraction f(x;54S) (0.ltoreq.x.ltoreq.L) of
the active vapor 54S (S=A, B, C) deposited on the substrate 51 can
be caused to vary linearly with lateral distance coordinate x from
the left end of the substrate as
f(x;54A)=a1+b1.multidot.x, (4A)
f(x;54B)=a2+b2.multidot.x, (4B)
f(x;54C)=a3+b3.multidot.x, (4C)
[0035] where the magnitudes and signums of the coefficients a1, a2,
a3, b1, b2 and b3 are independently chosen, subject to the
constraint
0.ltoreq.f(x;54A)+f(x;54B)+f(x;54C).ltoreq.1(0.ltoreq.x.ltoreq.L).
(5)
[0036] For example, the coefficients b1 and b2 may be positive and
negative, respectively, so that the relative or absolute
concentrations of the vapors 54A and 54B are increasing and
decreasing, respectively, as the coordinate x increases, as
illustrated in FIG. 5A. The linear changes in concentration with
the coordinate x in Eqs. (4A)-(4C) may be replaced by nonlinear
changes in one or more of the quantities f(x;54S) by appropriate
control of the flow controllers 55A-55C and of the location of the
movable mask 58. One possible result of such nonlinear deposition
is shown in FIG. 5B. If a uniform concentration of an active vapor
54S is desired, the substrate 51 can be rotated during the time(s)
this vapor is deposited. One or both of the concentrations of the
deposited vapors 54A and 54B may be linear or may be nonlinear.
Combinatorial deposition of two or more vapors 54S occurs by CVD,
either one layer at a time or simultaneously, producing a
multilayer or an in situ deposition, in the apparatus shown in FIG.
4.
[0037] The source of each active vapor 54S (S=A, B, C) can be (1) a
solid or liquid substance packed into the corresponding evaporator
53S, (2) a solid powder or liquid dissolved into an organic solvent
or (3) any other source that will provide a vapor substance of the
desired precursor when heated to a temperature in a selected
temperature range. Where source (1) is present, vaporizer
temperature and flow rate of the carrier gas can be used to control
the rate of delivery of a precursor. Where source (2) is present,
the rate of delivery of a precursor is controlled by vaporizer
temperature, carrier gas flow rate and pumping rate of the
precursor solution into the corresponding vaporizer unit, such as
53A.
[0038] Combinatorial deposition on a substrate 61 can also be
performed by in situ co-deposition, using the apparatus shown in
FIGS. 6A and 6B. A precursor vapor flux f.sub.64S (S=A, B, C),
which may include a mixture of vapors at any given time, is
incident upon two or more spaced apart movable masks, 68-1 and
68-2, in FIG. 6A that together form one or more movable slots or
apertures 67, as shown in FIG. 6B. The relative mix of vapors 64S
may vary from one time to another time, and the slot(s) 67 need not
move at a uniform rate across the exposed surface of the substrate
61. Further, the width w.sub.slot(t) of a slot or aperture may vary
according to a selected function with time t so that the slot
aperture is wider at some times than at other times and may close
altogether at one or more times. If the slot width w.sub.slot(t) is
fixed and the rate v(t) at which the slot moves across the exposed
surface of the substrate 61 is uniform, in situ co-deposition of
two vapors with constant concentration gradients can be obtained,
as illustrated in FIG. 5A, by varying the relative concentrations
of the vapors 64A and 64B with time. This approach will produce a
chemical mixture of (64A).sub.u(x)(64B).sub.(1-u(x)) as x varies
from 0 to L across the exposed surface of the substrate 61, with
the index u(x) increasing or decreasing, linearly or nonlinearly,
with increasing x. The concentration fractions of the two or more
components, 64A and 64B, may also be arranged to vary nonlinearly,
as illustrated in FIG. 5B.
[0039] As a first alternative, the masks 68-1 and 68-2 are fixed in
location and a substrate stepper motor or other substrate movement
device 70 moves the substrate 51 transversely. As a second
alternative, the mask movement devices 69-1 and 69-2 and the
substrate movement device 70 independently move the substrate 51
and the masks, 58-1 and 58-2, transversely relative to the
direction of the flux f.sub.64S.
[0040] One advantage of the in situ co-deposition process
illustrated in FIGS. 6A and 6B, over the multilayer process,
illustrated in FIG. 3, is that the post-anneal procedure may be
eliminated or minimized in the co-deposition process. Another
advantage is that the temperature at which a post-anneal process,
if any, is performed can be reduced. The in situ co-deposition
process, illustrated in FIGS. 6A and 6B, can also be applied to
co-sputtering, to co-evaporation, to co-ablation (e.g., using a
laser ablating source), and to molecular beam epitaxy (MBE). Among
these approaches, ion beam sputtering and MBE are especially
attractive, because the deposition rates for these approaches can
be more closely controlled through monitoring with a negative
feedback loop.
[0041] FIG. 7A illustrates another co-deposition approach, using
two or more nuzzle slits, 75A and 75B, located at the exits of two
vapor source chambers, 73A and 73B, respectively. Vapors, 74A and
74B, that exit through the nuzzle slits, 75A and 75B, may be
arranged to vary independently in a linear or nonlinear manner with
respective angles, .theta.A and .theta.B, measured relative to a
reference line RR such as shown in FIG. 7A. FIG. 7B schematically
illustrates a nuzzle slit, in which a throat associated with the
slit is shaped to produce a desired relative flow rate
.psi.(.theta.) that varies in a controllable manner with an angle
.theta., measured relative to a reference line. An example of a
nuzzle slit is a garden hose nozzle, in which movement of a small
flow obstruction changes the spread of water that issues from the
hose.
[0042] With reference to FIG. 8, assume that the nuzzle slits, 75S
(S=A, B), are located at a distance D from the exposed planar
surface of the substrate and are designed to provide flow
rates,.psi.(.theta.A) and .psi.(.theta.B), given by 2 ( / x ) ( A )
sin ( A ) = - { sin 2 A / D } ( / A ) ( A ) sin ( A ) = b1 =
constant , ( 6 A ) ( / x ) ( B ) sin ( B ) = - { sin 2 B / D } ( /
B ) ( B ) sin ( B ) = b2 = constant , ( 6 B )
[0043] where b1 and b2 are selected constant coefficients. The
deposition rates, g(x;74A) and g(x;74B), of the respective vapors,
74A and 74B, on the substrate 71 will then vary linearly according
to
g(x;74A)=a1+b1.multidot.x (7A)
g(x;74B)=a2+b2.multidot.x (7B)
[0044] where a1 and a2 are appropriate constant coefficients. This
will provide a linearly varying co-deposition mix on the exposed
surface of the substrate 71 of (74A).sub.(x/L)(74B).sub.(1-x/L) as
the coordinate x varies from 0 to x/L. An ultrasonic nuzzle can be
used for the apparatus shown in FIGS. 7A and 7B.
[0045] A CVD approach is suitable where the precursor vapors can be
pressurized and deposited according to the linear patterns in Eqs.
(7A) and (7B). However, the nuzzle approach may be difficult to
apply using ion beam sputtering, co-sputtering, co-evaporation,
co-ablation and MBE, because the precursor particles used in these
processes are generated by point sources and the normal deposition
profile on a substrate is Gaussian, rather than varying linearly
with the coordinate x. A magnetron sputtering gun can be
constructed to provide a nuzzle configuration. Ion beam deposition,
for example, as developed by SKION Corporation in Hoboken, N.J.,
can also be used with this approach to deposit C, Si, Ni, Cu and
other metals and alloys, using an electrical field to control the
initial velocity of the ion that issues from the ion beam
sputtering source.
[0046] Two or more nuzzle slits and corresponding vapor sources can
also be arranged in a non-parallel array, as illustrated in FIG. 9,
to provide a two-dimensional relative concentration fraction f(x,y)
of the three vapors, 84A, 84B and 84C, given by
f(x,y;A;B;C)=(84A).sub.h(x,y;A)(84B).sub.h(x,y;B)(84C).sub.h(x,y;C),
(8)
[0047] where h(x,y;A), h(x,y;B) and h(x,y;C) are two-dimensional
distributions that are determined by the designs of the nuzzle
slits 85A, 85B and 85C, respectively. Three nuzzle slits may be
arranged at the vertices of, or along three sides of, a general
triangle, not necessarily isosceles or equilateral.
[0048] FIGS. 10A and 10B illustrate, schematically and graphically,
an embodiment of the invention. A chemical component source 91
provides a chemical component, denoted A, that is to be deposited
on a substrate 99. In a preferred embodiment, the source 91
provides a flux f.sub.A of the chemical component A that is
approximately uniform in a selected coordinate direction z. If the
flux f.sub.A is not approximately uniform in a plane .PI.
perpendicular to the z-direction, but is known as a function of the
Cartesian coordinates, x and y, measured in the plane .PI., the
details of this embodiment can be varied to achieve substantially
the same result. Alternatively, a portion of the flux f.sub.A from
the source can be masked to provide an approximately uniform flux
through the mask aperture(s).
[0049] In this embodiment, a mask 93 having a sequence of spaced
apart apertures 95-i (i=1, 2, 3, 4, . . . ) with aperture widths di
is positioned in an xy-plane, transverse to the z-direction of the
flux f.sub.A from the source 91 and spaced apart from the source by
a selected distance s1. The mask 93, in turn, is spaced apart from
the substrate 99 by a distance s2. The space 97 between the mask 93
and the substrate 99 is either evacuated to a high vacuum or is
filled with a selected gas at a selected low density .rho.97.
[0050] The aperture 95-i has an aperture width di in a selected
x-direction, and two adjacent apertures, such as 95-2 and 95-3,
have a selected aperture spacing distance D(2,3). In one version of
this embodiment, the aperture spacings D(i,i+1) are uniform. In
another version of this embodiment, the aperture spacings D(i,i+1)
are variable according to the substrate deposition pattern desired.
If a single aperture 95-i receives the flux f.sub.A from the source
91, the precursor particles A passed through the mask 93 at the
aperture 95-i will arrive at and deposit on the substrate 99 in an
approximately Gaussian or normally distributed concentration
pattern C(x;i), as a function of the transverse coordinate x, as
illustrated in FIG. 10B. However, if a collection of three or more
apertures 95-i is provided with suitable aperture widths di and
suitably chosen aperture spacings D(i,i+1), the sum of these
apertures will produce a concentration envelope C(x) (or C(x,y)) of
selected shape at the substrate shown in FIG. 10B. The aperture
widths and aperture spacings shown in FIG. 10A are relatively large
for display purposes. In practice, these dimensions would be
relatively small, probably in the range 0.01-1 mm, or larger or
smaller where suitable.
[0051] The concentration envelope C(x) may be chosen to be
linear,
C(x)=a+b.multidot.x, (9A)
[0052] or to be linear-symmetric,
C(x)=a+b.vertline.x.vertline., (9B)
[0053] or to obey a more general power law
C(x)=a'+b'.multidot..vertline.x.vertline.q(q.noteq.0), (9C)
[0054] where a, b, a', b' and q are selected real numbers. The
particular concentration envelope C(x) (or C(x,y)) produced will
depend upon the parameters di (aperture widths), D(i,i+1) (aperture
spacings), s1 (source-to-mask spacing), s2 (mask to substrate
spacing), the gas, if any, and its density .rho.97 in the space
101, the range of flux f.sub.A of the chemical component A produced
in the z-direction by the source 91, and other parameters
describing the source.
[0055] The concentration envelope C(x) may be modeled as a faltung
integral that takes into account the aperture widths and aperture
spacings chosen for the mask 93, namely
C(x)=.intg.F(x')Ap(x')H(x-x')dx', (10)
[0056] where F(x') represents the A particle flux f.sub.A and
Ap(x') is a mask characteristic function (=1 where a mask aperture
is present;=0 where no mask aperture is present). The presence of
the faltung function H(x-x') in the integrand in Eq. (10) accounts
for the fact that an A component particle that passes through the
mask at a transverse location coordinate x' may become deposited on
the substrate at another transverse location coordinate x, due to
scattering, initial velocity vector of the particle and other
interference phenomena. A suitable approximation for a faltung
function for a single aperture is
H(w)=(2.pi..sigma..sup.2).sup.-1/2exp{-w.sup.2/2.sigma..sup.2},
(11)
[0057] where the parameter .sigma. (having the units of length)
characterizes the transverse spread of flux through a single
aperture. Invoking the superposition principle, this faltung
function, with possibly a different .sigma. parameter, may be used
for each aperture in the mask.
[0058] The concentration envelope C(x) shown in FIG. 10B may be
reproduced in one direction only, if each aperture 95-i in the mask
is uniform in a second transverse coordinate direction y to produce
a concentration envelope C(x,y) that depends non-trivially on each
of the coordinates x and y.
[0059] Each chemical component A, B, . . . to be deposited on the
substrate may have a different mask with a different aperture
pattern and may have different separation distances, s1 and s2. For
example, two chemical components, A and B, may (but need not) use
the same mask and/or the same separation distances, s1 and s2. FIG.
11A illustrates use of two sources, 101A and 101B, each with its
own component mask, 103A and 103B, which are optionally part of an
overall mask 103, positioned between the two sources and a
substrate 109. The net effect of deposit of components A and B on
the substrate 109, either simultaneously or sequentially, is the
concentration envelope C(x;A;B), which is a sum of the
concentration envelopes C(x;A) and C(x;B) shown in FIG. 11B.
[0060] As a first alternative for multi-component deposition, two
or more chemical components, A, B, . . . , each with its own source
111A, 111B, etc. can be simultaneously deposited on a single
substrate 119, as illustrated in FIG. 12. A single mask 113, having
suitable aperture widths and aperture spacings (not shown
explicitly in FIG. 12), is positioned transverse to a direct path
or line of sight from at least one source 111A, 111B, etc. to the
common substrate 1 19. The first source 111A and mask 113 produce a
first concentration envelope C(x;A) on the substrate 119; and the
second source 111B and mask 113 produce a second concentration
envelope C(x;B) on the substrate 119. The sum of these
concentration envelopes,
f(x;A;B)=[A].multidot.C(x;A)+[B].multidot.C(x;B), (12)
[0061] defines the total concentration of the chemical components,
A and B, deposited on the substrate. Subsequent processing of the
coated substrate, for example, by thermally driven diffusion, may
produce a concentration pattern that differs from the initial total
concentration envelope f(x;A;B).
[0062] As a second alternative, illustrated in FIG. 13, each of two
or more sources, 121A, 121B and 121C, arranged adjacent to and
above two or more sides of a polygon (a triangle in FIG. 13) may
have its own mask, 123A, 123B and 123C, respectively, and each
source mask combination will produce a different two-dimensional
concentration envelope, C1(x,y;A) and C(x,y;B) and C(x,y;C), on a
common substrate 129 that is positioned adjacent to the sources,
with the masks being located between the sources and the substrate.
In this embodiment, each of the masks can be separately designed,
and thus optimized, for the particular concentration envelope
desired for that chemical component.
[0063] FIG. 14 illustrates an alternative arrangement of the system
in FIG. 13, in which sources, 131A, 131B and 131C, are located
adjacent to and above two or more vertices of a polygon, and masks,
133A, 133B and 133C, are located between a common substrate 139 and
the respective sources.
[0064] FIG. 15 is a flow chart generally illustrating the processes
used to practice the invention. In a process 141, first and second
fluxes of respective first and second chemical components are
directed toward a substrate. In a process 143, a mask, having at
least one opening (e.g., an aperture or an edge) is provided across
the flux field that allows first and second selected portions of
the respective first and second chemical components to be deposited
on selected first and second portions of the substrate surface. In
a process 145. (optional), the mask is moved transversely to at
least one of the first and second flux directions at a selected
movement rate, to provide a desired concentration of the first and
second components on the substrate surface.
* * * * *