U.S. patent application number 11/027825 was filed with the patent office on 2005-07-07 for apparatus for forming thin layers of materials on micro-device workpieces.
Invention is credited to Derderian, Garo J., Sandhu, Gurtej.
Application Number | 20050145337 11/027825 |
Document ID | / |
Family ID | 29249097 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050145337 |
Kind Code |
A1 |
Derderian, Garo J. ; et
al. |
July 7, 2005 |
Apparatus for forming thin layers of materials on micro-device
workpieces
Abstract
A method of forming a layer on a micro-device workpiece includes
dispensing a first pulse of a first precursor at a first region of
the workpiece to flow toward a second region of the workpiece. The
second region of the workpiece is located radially outward relative
to the first region of the workpiece. The embodiment of this method
further includes dispensing a first pulse of a purge gas at the
first region of the workpiece to flow toward the second region of
the workpiece after terminating the first pulse of the first
precursor. Additionally, this embodiment also includes dispensing a
second pulse of a first precursor at the second region of the
workpiece to flow radially outward concurrently with dispensing the
first pulse of a purge gas in the first region of the workpiece.
The first pulse of the purge gas is terminated at the first region
of the workpiece, and the second pulse of the first precursor is
terminated at the second region. At this stage, the method further
includes dispensing a first pulse of a second precursor at the
first region of the workpiece to flow radially outward toward the
second region, and dispensing a second pulse of the purge gas at
the second region of the workpiece to flow radially outward
concurrently with the first pulse of the second precursor in the
first region. A single cycle of the process can further include
dispensing a third pulse of the purge gas onto the first region of
the workpiece to flow radially outward after terminating the first
pulse of the second precursor, and concurrently dispensing a second
pulse of the second precursor in the second region to flow radially
outward.
Inventors: |
Derderian, Garo J.; (Boise,
ID) ; Sandhu, Gurtej; (Boise, ID) |
Correspondence
Address: |
PERKINS COIE LLP
PATENT-SEA
P.O. BOX 1247
SEATTLE
WA
98111-1247
US
|
Family ID: |
29249097 |
Appl. No.: |
11/027825 |
Filed: |
December 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11027825 |
Dec 29, 2004 |
|
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|
10133909 |
Apr 25, 2002 |
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6861094 |
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Current U.S.
Class: |
156/345.34 ;
427/248.1 |
Current CPC
Class: |
C23C 16/45565 20130101;
C23C 16/45574 20130101; C23C 16/45527 20130101 |
Class at
Publication: |
156/345.34 ;
427/248.1 |
International
Class: |
C23C 016/00; C23F
001/00 |
Claims
1-29. (canceled)
30. A reactor for forming a layer of material on a micro-device
workpiece, comprising: a reaction chamber having an inlet and an
outlet; a workpiece support in the reaction chamber between the
inlet and the outlet, the workpiece support having a first zone and
a second zone located radially outward relative to the first zone;
a gas distributor in the reaction chamber between the inlet and the
workpiece support, the gas distributor comprising a first
dispensing section and a second dispensing section located radially
outward relative to the first dispensing section, first dispensing
section being configured to dispense at least one of a first
precursor, a purge gas or a second precursor over the first zone,
and the second dispensing section being configured to dispense a
different one of the first precursor, the purge gas or the second
precursor over the second zone independently from the first
dispensing section.
31. The reactor of claim 30 wherein the gas distributor comprises:
a gas box to receive flows of the first precursor, the purge gas
and the second precursor; a distributor plate having a plurality of
first passageways juxtaposed to the first zone of the support and a
plurality of second passageways juxtaposed to the second zone of
the support, wherein the distributor plate is proximate to the gas
box; and an annular divider in the gas box aligned with a boundary
between the first zone and the second zone, the divider forming a
first compartment over the first passageways that defines the first
dispensing section and a second compartment over the second
passageways that defines the second dispensing section.
32. The reactor of claim 30 wherein the gas distributor comprises:
a distributor plate having a plurality of first passageways
juxtaposed to the first zone of the support and a plurality of
second passageways juxtaposed to the second zone of the support,
wherein the distributor plate is proximate to the gas box; a first
set of purge gas lines coupled to a purge gas set of the first
passageways; a second set of purge gas lines coupled to a purge gas
set of the second passageways; a first set of first precursor lines
coupled to a first precursor set of the first passageways; a second
set of first precursor lines coupled to a first precursor set of
the second passageway; a first set of second precursor lines
coupled to a second precursor set of the first passage ways; and a
second set of second precursor lines coupled to a second precursor
set of the second passageways.
33. The reactor of claim 30 wherein the gas distributor further
comprises a third dispensing section radially outward from the
second dispensing section, the third dispensing section being
configured to dispense one of the first precursor, the second
precursor or the purge gas over a third zone of the workpiece
support that is located radially outward from the second zone of
the workpiece support.
34. The reactor of claim 30 wherein the first dispensing section
has a circular shape over the first zone and the second dispensing
section has an annular shape over the second zone.
35. The reactor of claim 30 wherein: the first dispensing section
has a circular shape over the first zone; the second dispensing
section has an annular shape over the second zone; and the gas
dispenser has a third dispensing section having an annular shape
radially outward from the second dispensing section.
36. A reactor for forming a layer of material on a micro-device
workpiece, comprising: a reaction chamber having an inlet and an
outlet; a gas distributor in the reaction chamber between the inlet
and the outlet, the gas distributor having a plenum, a first
divider that partitions the plenum into a center compartment and a
first annular compartment radially outward from the center
compartment, and a distributor plate having a plurality of first
openings in the first compartment and a plurality of second
openings in the second compartment.
37. A reactor for forming a layer of material on a micro-device
workpiece, comprising: a reaction chamber having an inlet and an
outlet; a workpiece support in the reaction chamber between the
inlet and the outlet, the workpiece support having a first zone and
a second zone located radially outward relative to the first zone;
a gas distributor in the reaction chamber between the inlet and the
workpiece support, the gas distributor having a first plurality of
conduits in a first section juxtaposed to the first zone and a
second plurality of conduits in a second section juxtaposed to the
second zone, wherein the first plurality of conduits are coupled to
a gas supply to selective dispense at least one of a first
precursor, a purge gas or a second precursor over the first zone,
and wherein the second plurality of conduits are coupled to the gas
supply to concurrently dispense a different one of the first
precursor, the purge gas or the second precursor over the second
zone.
38. A system for forming a layer of material on a surface of a
micro-device workpiece, comprising: a gas supply assembly having a
first gas source for a first precursor, a second gas source for a
second precursor, and a third gas source for a purge gas; a
reaction chamber coupled to the gas supply; a workpiece support in
the reaction chamber, the support member having a first zone and a
second zone located radially outward relative to the first zone; a
gas distributor in the reaction chamber, the gas distributor being
coupled to the gas supply assembly, and the gas distributor having
a first dispensing section juxtaposed to the first zone of the
support and a second dispensing section juxtaposed to the second
zone of support; and a controller coupled to the gas supply
assembly, wherein the controller contains computer readable
instructions that cause the gas supply to dispense a first pulse of
a first precursor through the first dispensing section; dispense a
first pulse of a purge gas through the first dispensing section
after terminating the first pulse of the first precursor; and
dispense a second pulse of the first precursor through the second
dispensing section concurrently while dispensing the first pulse of
the purge gas.
39. A system for forming a layer of material on a surface of a
microelectronic workpiece, comprising: a gas supply assembly having
a first gas source for a first precursor, a second gas source for a
second precursor, and a third gas source for a purge gas; a
reaction chamber coupled to the gas supply; a workpiece support in
the reaction chamber; a gas distributor in the reaction chamber,
the gas distributor being coupled to the gas supply assembly, and
the gas distributor having a first dispensing section juxtaposed to
a central zone of the support and a second dispensing section
juxtaposed to an outer annular zone; and a controller coupled to
the gas supply assembly, wherein the controller contains computer
readable instructions that cause the gas supply to dispense a first
pulse of a first precursor from the first dispensing section to
flow radially outward over the central zone; dispense a first pulse
of a purge gas from the first dispensing section to flow radially
outward over the central zone after terminating the first pulse of
the first precursor; and dispense a second pulse of the first
precursor from the second section to flow radially outward over the
outer annular zone while concurrently dispensing the first pulse of
the purge gas.
Description
TECHNICAL FIELD
[0001] The present invention is related to the field of thin film
deposition in the manufacturing of microelectronic devices,
micromechanical devices and other types of micro-devices.
BACKGROUND
[0002] Thin film deposition techniques are widely used in the
manufacturing of microelectronic devices to form a coating on a
workpiece that closely conforms to the surface typography. The size
of the individual components in the devices is constantly
decreasing, and the number of layers in the devices is increasing.
As a result, the density of components and the aspect ratios of
depressions (e.g., the ratio of the depth to the size of the
opening) is constantly increasing. The size of the workpieces is
also increasing to provide more real estate for forming more dies
(i.e., chips) on a single workpiece. Many fabricators, for example,
are transitioning from 200 mm to 300 mm workpieces, and even larger
workpieces will likely be used in the future. Thin film deposition
techniques accordingly strive to produce highly uniform conformal
layers that cover the sidewalls, bottoms and corners in deep
depressions that have very small openings.
[0003] One widely used thin film deposition technique is Chemical
Vapor Deposition ("CVD"). In a CVD system, one or more precursors
that are capable of reacting to form a solid thin film are mixed in
a gas or vapor state, and then the precursor mixture is presented
to the surface of the workpiece. The surface of the workpiece
catalyzes the reaction between the precursors to form a thin solid
film that closely follows the contour of the surface typography on
the workpiece. The most common way to catalyze the reaction at the
surface of the workpiece is to heat the workpiece to a temperature
that causes the reaction.
[0004] Although CVD techniques are useful in many applications,
they also have several drawbacks. For example, if the precursors
are not highly reactive, then a high workpiece temperature is
needed to achieve a reasonable deposition rate. Such high
temperatures are typically not desirable because heating the
workpiece can be detrimental to the structures and other materials
that are already formed on the workpiece. Implanted or doped
materials, for example, migrate in the silicon substrate when a
workpiece is heated. On the other hand, if more reactive precursors
are used so that the reaction temperature of the workpiece can be
lower, then reactions may occur prematurely in the gas phase before
reaching the substrate. This is not desirable because the film
quality and uniformity may suffer, and also because it limits the
type of precursors that can be used. Thus, CVD techniques may not
be appropriate for many thin film applications.
[0005] Atomic Layer Deposition ("ALD") is another thin film
deposition technique that addresses several of the drawbacks
associated with CVD techniques. FIGS. 1A and 1B schematically
illustrate the basic operation of ALD processes. Referring to FIG.
1A, a layer of gas molecules A, coats the surface of a workpiece W.
The layer of the A.sub.x molecules is formed by exposing the
workpiece W to a first precursor gas containing A.sub.x molecules,
and then purging the chamber with a purge gas to remove excess
A.sub.x molecules. This process can form a monolayer of A.sub.x
molecules on the surface of the workpiece W because the A.sub.x
molecules at the surface are held in place during the purge cycle
by physical adsorption forces at moderate temperatures or
chemisorption forces at higher temperatures. The layer of A.sub.x
molecules is then exposed to a second precursor gas containing
B.sub.y molecules. The A.sub.x molecules react with the B.sub.y
molecules to form an extremely thin solid layer of material on the
workpiece W. The chamber is then purged again with a purge gas to
remove excess B.sub.y molecules.
[0006] FIG. 2 illustrates the stages of one cycle for forming a
thin solid layer using ALD techniques. A typical cycle includes (a)
exposing the workpiece to the first precursor A.sub.x (b) purging
excess A.sub.x molecules, (c) exposing the workpiece to the second
precursor B.sub.y, and then (d) purging excess B.sub.y molecules.
Several cycles are repeated to build a thin film on a workpiece
having the desired thickness. For example, each cycle may form a
layer having a thickness of approximately 0.5-1.0 .ANG., and thus
it takes approximately 60-120 cycles to form a solid layer having a
thickness of approximately 60 .ANG..
[0007] FIG. 3 schematically illustrates an ALD reactor 10 having a
chamber 20 coupled to a gas/vapor supply 30 and a vacuum 40. The
reactor 10 also includes a heater 50 that supports the workpiece W
and a gas dispenser 60 in the chamber 20. The gas dispenser 60
includes a plenum 62 operatively coupled to the gas supply 30. The
gas dispenser 60 also includes a distributor plate 70 having a
plurality of holes 72. In operation, the heater 50 heats the
workpiece W to a desired reaction temperature, and the gas supply
30 selectively injects the first precursor A.sub.x, the purge gas,
and the second precursor B.sub.y as shown above in FIG. 2. The
vacuum 40 maintains a negative pressure in the chamber to draw the
gasses from the gas distributor 60 across the workpiece W and then
through an outlet of the chamber 20.
[0008] One drawback of ALD processing is that the film thickness
may be different at the center of the workpiece than at the
periphery. To overcome this problem, the center of some distributor
plates do not have any holes 72. In practice, however, this may
cause the film at the center of the workpiece to be thinner than
the film at the periphery. Moreover, the center portion of such
plates may become coated with the solid material because it is
difficult to purge all of the precursors from this portion of the
gas distributor 60 during normal purge cycles.
[0009] Another drawback of ALD processing is that it has a low
throughput compared to CVD techniques. For example, ALD processing
typically takes about eight to eleven seconds to perform each
A.sub.x-purge-B.sub.y-purge cycle. This results in a total process
time of approximately eight to eleven minutes to form a thin layer
of only 60 .ANG.. In contrast to ALD processing, CVD techniques
only require about one minute to form a 60 .ANG. thick layer. The
low throughput of existing ALD techniques limits the utility of
this technology in its current state because ALD may be a
bottleneck in the fab. Thus, it would be useful to increase the
throughput of ALD techniques so that they can be used in a wider
range of applications.
SUMMARY
[0010] The present invention is directed toward reactors for
depositing materials onto a micro-device workpiece, systems that
include such reactors, and methods for depositing materials onto
micro-device workpieces. In one embodiment, a method of forming a
layer on a micro-device workpiece includes dispensing a first pulse
of a first precursor at a first region of the workpiece to flow
toward a second region of the workpiece. The second region of the
workpiece is located radially outward relative to the first region
of the workpiece. This embodiment further includes dispensing a
first pulse of a purge gas at the first region of the workpiece to
flow toward the second region of the workpiece after terminating
the first pulse of the first precursor, and concurrently dispensing
a second pulse of a first precursor at the second region of the
workpiece to flow radially outward while dispensing the first pulse
of the purge gas in the first region of the workpiece. The first
pulse of the purge gas and the second pulse of the first precursor
are then terminated. This embodiment further includes dispensing a
first pulse of a second precursor at the first region of the
workpiece to flow radially outward toward the second region, and
concurrently dispensing a second pulse of the purge gas at the
second region of the workpiece to flow radially outward while
dispensing the first pulse of the second precursor in the first
region. This embodiment continues by dispensing a third pulse of
the purge gas onto the first region of the workpiece to flow
radially outward after terminating the first pulse of the second
precursor, and concurrently dispensing a second pulse of the second
precursor in the second region to flow radially outward while
dispensing the third pulse of the purge gas.
[0011] This embodiment accordingly provides a continuous pulse
train in which discrete areas of the workpiece are exposed to one
of the first or second precursors while adjacent areas are exposed
to the purge gas. A continuous pulse train can accordingly be
presented to the surface of the wafer without having to completely
purge the first and second precursors from the entire surface area
of the workpiece during each purge cycle. This is expected to
greatly reduce the processing time for forming a layer of material
on the workpiece.
[0012] Another aspect of the invention is directed toward a reactor
for forming a layer of material on a micro-device workpiece. In one
embodiment, a reactor includes a reaction chamber having an inlet
and an outlet, and a workpiece support in the reaction chamber
between the inlet and the outlet. The workpiece support can have a
first zone and a second zone. The second zone is located radially
outward relative to the first zone. The reactor can further include
a gas distributor in the reaction chamber between the inlet and the
workpiece support. The gas distributor can comprise a first
dispensing section and a second dispensing section. The second
dispensing section is located radially outward relative to the
first dispensing section. The first dispensing section is
configured to dispense separate pulses of a first precursor, a
purge gas, or a second precursor over the first zone of the
workpiece support. The second dispensing section is configured to
dispense separate pulses of the first precursor, the purge gas, or
the second precursor over the second zone of the workpiece support
independently from the type of gas dispensed from the first
dispensing section. As such, the first dispensing section can
dispense one type of gas over the first zone while the second
dispensing section concurrently dispenses a different type of gas
over the second zone.
[0013] The reactor can be part of a system that further includes a
gas supply assembly and a controller coupled to the gas supply
assembly. The gas supply assembly can include a first gas source
for a first precursor, a second gas source for a second precursor,
and a third gas source for a purge gas. The controller can contain
computer readable instructions that cause the first precursor,
second precursor and purge gas to flow through the first and second
dispensing sections of the gas distributor in a manner that
effectuates embodiments of methods in accordance with the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1A and 1B are schematic cross-sectional views of
stages in atomic layer deposition processing in accordance with the
prior art.
[0015] FIG. 2 is a graph illustrating a cycle for forming a layer
using atomic layer deposition in accordance with the prior art.
[0016] FIG. 3 is a schematic representation of a system including a
reactor for depositing a material onto a microelectronic workpiece
in accordance with the prior art.
[0017] FIG. 4 is a schematic representation of a system having a
reactor for depositing a material onto a micro-device workpiece in
accordance with one embodiment of the invention.
[0018] FIGS. 5A-5E are schematic cross-sectional views illustrating
a method for depositing a material onto a micro-device workpiece
using the system of FIG. 4 in accordance with one embodiment of the
invention.
[0019] FIGS. 6A-6I are schematic cross-sectional views of another
method for depositing a material onto a micro-device workpiece in
accordance with another embodiment of the invention.
[0020] FIG. 7 is a schematic cross-sectional view of a gas
distributor for depositing a material onto a micro-device workpiece
in accordance with an embodiment of the invention.
[0021] FIG. 8 is a schematic cross-sectional view of another gas
distributor for depositing a material onto a micro-device workpiece
in accordance with yet another embodiment of the invention.
DETAILED DESCRIPTION
[0022] The following disclosure describes several embodiments of
reactors for depositing a material onto a micro-device workpiece,
systems including such reactors, and methods for depositing
materials onto micro-device workpieces. Many specific details of
the invention are described below with reference to depositing
materials onto micro-device workpieces. The term "micro-device
workpiece" is used throughout to include substrates upon which
and/or in which microelectronic devices, micromechanical devices,
data storage elements, read/write components, and other features
are fabricated. For example, micro-device workpieces can be
semiconductor wafers such as silicon or galium arsenide wafers,
glass substrates, insulative substrates, and many other types of
materials. The term "gas" is used throughout to include any form of
matter that has no fixed shape and will conform in volume to the
space available, which specifically includes vapors (i.e., a gas
having a temperature less than the critical temperature so that it
may be liquified or solidified by compression at a constant
temperature). Additionally, several aspects of the invention are
described with respect to Atomic Layer Deposition ("ALD"), but
certain aspects may be applicable to other types of deposition
processes. Several embodiments in accordance with the invention are
set forth in FIGS. 4-8 and the following text to provide a thorough
understanding of particular embodiments of the invention. A person
skilled in the art will understand, however, that the invention may
have additional embodiments, or that the invention may be practiced
without several of the details of the embodiments shown in FIGS.
4-8.
[0023] A. Deposition Systems
[0024] FIG. 4 is a schematic representation of a system 100 for
depositing a material onto a micro-device workpiece in accordance
with an embodiment of the invention. In this embodiment, the system
100 includes a reactor 110 having a reaction chamber 120 coupled to
a gas supply 130 and a vacuum 140. For example, the reaction
chamber 120 can have an inlet 122 coupled to the gas source
assembly 130 and an outlet 124 coupled to the vacuum 140.
[0025] The gas supply 130 includes a plurality of gas sources 132
(identified individually as 132a-c), a valve assembly 133 having a
plurality of valves, and a plurality of gas lines 136 and 137. The
gas sources 132 can include a first gas source 132a for providing a
first precursor A, a second gas source 132b for providing a second
precursor B, and a third gas source 132c for providing a purge gas
P. The first and second precursors A and B are the gas or vapor
phase constituents that react to form the thin, solid layer on the
workpiece W. The purge gas P can be a suitable type of gas that is
compatible with the reaction chamber 120 and the workpiece W. The
gas supply 130 can include more gas sources 132 for applications
that require additional precursors or purge gases in other
embodiments. As explained in more detail below, the valve assembly
is operated by a controller 142 that generates signals for pulsing
the individual gases through the reaction chamber 120.
[0026] The reaction chamber 110 in the embodiment illustrated in
FIG. 4 also includes a workpiece support 150 and a gas distributor
160 in the reaction chamber 120. The workpiece support 150 is
typically heated to bring the workpiece W to a desired temperature
for catalyzing the reaction between the first precursor A and the
second precursor B at the surface of the workpiece W. The workpiece
support 150 is a plate with a heating element in one embodiment of
the reaction chamber 120. The workpiece support 150, however, may
not be heated in other applications. The workpiece support 150 has
a first zone Z.sub.1 at a central portion C of the workpiece W and
a second zone Z.sub.2 at an outer portion of the workpiece W. The
second zone Z.sub.2 in the embodiment shown in FIG. 4 is an annular
region radially outward from the first zone Z.sub.1. The workpiece
support 150 can have more than two zones in other embodiments as
explained below with reference to FIGS. 6A-6I.
[0027] The gas distributor 160 is positioned at the inlet 122 of
the reaction chamber 120. The gas distributor 160 includes a first
dispensing section 161a and a second dispensing section 161b. The
first dispensing section 161a is generally juxtaposed to the first
zone Z.sub.1, and the first dispensing section 161a is coupled to
the valve assembly 133 to dispense at least one of the first
precursor A, the second precursor B, or the purge gas P over the
first zone Z.sub.1. The first dispensing section 161a can have a
circular shape to create a gas flow F.sub.1 that flows radially
outward from the center region C of the workpiece W. The second
dispensing section 161b can have an annular shape that
concentrically surrounds the first dispensing section 161a to be
juxtaposed to the second zone Z.sub.2. The second dispensing
section 161b is coupled to the valve assembly 133 to dispense a
different one of the first precursor A, the second precursor B, or
the purge gas P over the second zone Z.sub.2 independently from the
first dispensing section 161a. The second dispensing section 161b
accordingly produces a second gas flow F.sub.2 that flows radially
outward across the workpiece W. In operation, the first dispensing
section 161a can dispense a pulse of one type of gas over the first
zone Z.sub.1 while the second dispensing section 161b
simultaneously dispenses a pulse of a different type of gas over
the second zone Z.sub.2. The separate pulses of gases that form the
gas flows F.sub.1 and F.sub.2 are coordinated to provide the
desired combination of gases at separate regions on the surface of
the workpiece. For example, pulse trains of different gases are
dispensed through each of the first and second dispensing sections
161a-b concurrently to provide a continuous deposition process that
does not completely purge the first and/or the second precursor
from the entire surface of the workpiece until the end of the
deposition process.
[0028] B. Methods for Forming Layers on Micro-Device Workpieces
[0029] The system 100 shown in FIG. 4 can be used to perform
several different methods for forming layers on micro-device
workpieces. In one embodiment, the system 100 provides a continuous
pulse train that dispenses pulses of the first precursor, the
second precursor and the purge gas in a manner that causes the
pulses of gases to flow radially outward across the workpiece. The
pulse train of gases is controlled to concurrently dispense the
purge gas to various zones of the workpiece while separately
dispensing at least one of the first or second precursors to
another zone of the workpiece. It is anticipated that providing a
continuous pulse train that concurrently dispenses the purge gas
and the precursors to the workpiece will reduce the cycle time for
building a layer.
[0030] FIGS. 5A-5E illustrate one embodiment of a method that the
system 100 can perform to provide a continuous pulse train of
precursors and purge gas to the workpiece W. Referring to FIG. 5A,
this embodiment includes dispensing a first pulse of the first
precursor A from the first dispensing section 161a. The first pulse
of the first precursor A flows downward to the workpiece W and then
radially outward from a center region of a workpiece aligned with
the first zone Z.sub.1 of the support 150. FIG. 5B illustrates a
subsequent stage of the method that includes dispensing a first
pulse of the purge gas P from the first dispensing section 161a
after terminating the first pulse of the first precursor A, and
concurrently dispensing a second pulse of the first precursor A
from the second dispensing section 161b. The first pulse of the
purge gas P flows radially outward above the first zone Z.sub.1,
and the second pulse of the first precursor A flows radially
outward across a first outer region of the workpiece W over the
second zone Z.sub.2. The first pulse of the purge gas P accordingly
purges excess molecules of the first precursor A from the center
portion of the workpiece over the zone Z.sub.1, and the second
pulse of the first precursor A simultaneously covers the outer
region of the workpiece in the zone Z.sub.2.
[0031] FIG. 5C illustrates a stage of the method that occurs after
the stage shown in FIG. 5B. This stage of the method includes
dispensing a first pulse of the second precursor B from the first
dispensing section 161a and concurrently dispensing a second pulse
of the purge gas P from the second dispensing section 161b. The
first pulse of the second precursor typically begins after
terminating the first pulse of the purge gas and flows radially
outward from the center region. The first pulse of the second
precursor B accordingly reacts with the molecules of the first
precursor A that remain on the workpiece W over the zone Z.sub.1 to
form a solid layer in the center region of the workpiece W. The
second pulse of the purge gas flows radially outward to purge
excess molecules of the second pulse of the first precursor A
(shown in FIG. 5B) from the outer region of the workpiece over the
second zone Z.sub.2.
[0032] FIG. 5D illustrates still a later stage of this method that
includes dispensing a third pulse of the purge gas P from the first
dispensing section 161a and concurrently dispensing a second pulse
of the second precursor B from the second dispensing section 161b.
The third pulse of the purge gas P flows downwardly to the center
region of the workpiece W over the first zone Z.sub.1, and then it
flows radially outward. The second pulse of the second precursor B
flows radially outward through the first outer region of the
workpiece over the second zone Z.sub.2. The second pulse of the
second precursor B accordingly reacts with the molecules of the
first precursor A that remain on the workpiece W over the second
zone Z.sub.2 to continue forming the solid layer in the outer
region of the workpiece. The stages of the method shown in FIGS.
5A-5D accordingly form a very thin layer of material on the
workpiece.
[0033] FIG. 5E illustrates a later stage of this method in which
the pulse train is repeated by dispensing another pulse of the
first precursor A from the first dispensing section 161a, and
concurrently dispensing another pulse of the purge gas P from the
second dispensing section 161b. The method can continue by
repeating the foregoing stages until the thickness of the deposited
layer is within a desired range.
[0034] The particular embodiment of the method shown in FIGS. 5A-5E
is expected to reduce the cycle time for separately dispensing the
first and second precursors to the surface of the workpiece W. Many
conventional processes typically purge excess molecules of one type
of precursor from the entire surface of the workpiece before
introducing the other type of precursor as explained above with
reference to FIG. 2. The embodiment of the method set forth in
FIGS. 5A-5E is expected to require less time because it does not
purge the excess of one precursor from the entire area over the
workpiece before introducing a pulse of the other precursor. This
embodiment accordingly does not need the long purge pulses that are
used in conventional ALD processing. The first and second
precursors, however, are still inhibited from mixing except at the
surface of the workpiece W. Therefore, the method set forth in
FIGS. 5A-5E is expected to provide the advantages of conventional
ALD processing with a shorter cycle time to improve the
throughput.
[0035] Another embodiment of the method for forming layers on
micro-device workpieces shown in FIGS. 5A-5E involves adjusting the
concentration of the pulses of the first precursor A, the second
precursor B, and/or the purge gas P relative to the location on the
workpiece W. The concentration of the particular pulses can be
adjusted by controlling the mass transfer rate of the various gases
from the first and second dispensing sections 161a and 161b. For
example, the first pulse of the first precursor A shown in FIG. 5A
and the first pulse of the second precursor B shown in FIG. 5C from
the first dispensing section 161a can be at a relatively high mass
transfer rate to increase the concentration of precursor molecules
over the center region of the workpiece. The second pulse of the
first precursor A from the second dispensing section 161b shown in
FIG. 5B, and the second pulse of the second precursor B from the
second dispensing section 161b shown in FIG. 5E can be at lower
mass transfer rates because some of the molecules from the first
pulses of these precursors will flow from the center region of the
workpiece W to the first outer region of the workpiece W. One
particular embodiment of a method in accordance with the invention
can accordingly provide a continuous pulse train that maintains the
same concentration of precursor molecules across the surface of the
workpiece. Such an embodiment can include increasing or decreasing
the concentration of the precursors with increasing radius across
the workpiece. For example, the concentration of the precursors can
decrease with each pulse at an increasing radial location. This is
expected to be particularly useful because reducing the amount of
precursors reduces the number of molecules that must be purged from
each region of the workpiece by the pulses of purge gas.
Additionally, reducing the concentration of the precursors with
increasing radius is expected to reduce the consumption of
precursors. As a result, this particular embodiment of the method
is expected to produce a highly uniform layer on the surface of the
workpiece W because it can continuously control the saturation of
the precursors across the workpiece.
[0036] FIGS. 6A-6I illustrate a method for forming a layer on a
micro-device workpiece in accordance with another embodiment of the
invention. The embodiments of the method illustrated in FIGS. 6A-6I
can be performed using the system 100 set forth above with respect
to FIG. 4. The gas distributor 160 in this embodiment, however,
includes six separate gas dispensing sections 161a-f. The first
dispensing section 161a is located over a center region C of the
workpiece W that is aligned with the first zone Z.sub.1 of a
support 150. The second dispensing section 161b through the sixth
dispensing section 161f are annular dispensing sections that are
aligned with the first through the fifth outer regions
R.sub.1-R.sub.5 of the workpiece W, which are in turn aligned with
the second through the sixth zones Z.sub.2-Z.sub.6 of the support
150, respectively.
[0037] FIG. 6A illustrates an initial stage of this method in which
a first pulse of the first precursor A is dispensed from the first
dispensing section 161a to flow to the center region C of the
workpiece W. FIG. 6B illustrates a subsequent stage in which a
first pulse of the purge gas P is dispensed from the first
dispensing section 161a and a second pulse of the first precursor
is dispensed from the second dispensing section 161b. FIG. 6C
illustrates yet another stage in which a first pulse of the second
precursor B is dispensed from the first dispensing section 161a, a
second pulse of the purge gas P is dispensed from the second
dispensing section 161b, and a third pulse of the first precursor A
is dispensed from the third dispensing section 161c. FIG. 6D
illustrates a subsequent stage in which a fourth pulse of the first
precursor A is dispensed from the fourth dispensing section 161d, a
third pulse of the purge gas P is dispensed from the third
dispensing section 161c, a second pulse of the second precursor B
is dispensed from the second dispensing section 161b, and a fourth
pulse of the purge gas P is dispensed from the first dispensing
section 161a. FIGS. 6E-6I illustrate subsequent stages of this
method in which additional pulses of the first precursor A, purge
gas P, and second precursor B are selectively and independently
pulsed through the first through the sixth dispensing sections
161a-f in an order that separately exposes the various regions of
the workpiece W to one precursor at a time. The progression of the
pulses in the pulse train can be repeated in a similar pattern to
continuously expose individual regions of the workpiece to the
purge gas while exposing other regions of the workpieces to a
single one of either the first precursor A or the second precursor
B.
[0038] The embodiment of method set forth in FIGS. 6A-6I is
expected to produce similar results and have similar benefits as
the methods described above with reference to FIGS. 5A-5F. One
possible difference that may occur is that the pulses in the method
set forth in FIGS. 6A-6I may be controlled more accurately because
the surface area on the workpiece of each pulse is smaller. The
higher resolution of pulses may accordingly provide better results
and more control over the ALD process.
[0039] C. Gas Distributors
[0040] FIG. 7 is a cross-sectional view of a gas distributor 160a
having a first dispensing section 161a and a second dispensing
section 161b. The gas distributor 160a includes a gas box 164, a
divider 165 in the gas box 164, and a distributor plate 170. The
divider 165 can be an annular wall in the gas box 164 that defines
a first compartment 166 and a second compartment 168. The first
compartment 166 can be a central compartment having a circular
shape, and the second compartment 168 can be an annular compartment
that is located radially outward from the first compartment 166.
The first and second compartments 166 and 168 are coupled to gas
lines that can independently provide the first precursor A, the
second precursor B or the purge gas P to the first or second
compartments 166 or 168. The distributor plate 170 has a plurality
of passageways 172 through which the gas can flow from the
compartments 166 and 168 downward toward the workpiece (not shown
in FIG. 7).
[0041] In operation, a pulse of one type of gas flows through the
first compartment 166 while a pulse of a different type of gas
simultaneously flows through the second compartment 168 to provide
the pulse trains described above with reference to FIGS. 5A-5E. The
gas distributor 160a can include more than two compartments, such
as one having six compartments to perform the particular
embodiments of the methods set forth in FIGS. 6A-6I. It will be
appreciated that the gas distributor 160a can have several other
configurations in which the first precursor A, the second precursor
B, and the purge gas P can be selectively dispensed from different
portions of the distributor plate 170.
[0042] FIG. 8 illustrates an embodiment of another gas distributor
160 for use in the system 100 (FIG. 4). In this embodiment, the gas
distributor 160b includes a circular first dispensing section 161a
and an annular second dispensing section 161b outside of the first
dispensing section 161a. The gas distributor 160 can include a gas
box 164 and a distributor plate 170. The distributor plate 170
includes a plurality of passageways 172. The gas distributor 160b
further includes a plurality of dedicated conduits or gas lines
173, 174 and 175 that are coupled to individual passageways 172.
Each of the gas lines 173 in the first and second dispensing
sections 161a and 161b can be coupled to different valves that
independently supply the purge gas P to a purge set of the
passageways 172 in the first dispensing section 161a and purge set
of passageways 172 in the second dispensing section 161b. The gas
lines 174 in the first and second dispensing sections 161a and 161b
can be coupled to different valves that independently provide the
first precursor A to a first precursor set of passageways 172 in
the first dispensing section 161a and a first precursor set of
passageways 172 in the second dispensing section 161b. The gas
lines 175 can be coupled to different valves that independently
provide the second precursor B to a second precursor set of
passageways 172 in the first dispensing section 161a and a second
precursor set of passageways 172 in the second dispensing section
161b. As a result, each passageway 172 in the distributor plate 170
is dedicated to dispensing one type of gas to the workpiece. This
is expected to reduce mixing of the first and second precursors A
and B within the gas distributor 160 to enhance the quality of the
film that is deposited onto the workpiece.
[0043] From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the spirit and scope of the invention.
For example, although the foregoing embodiments illustrate circular
reactors and gas distributors, several aspects of the invention are
also useful in linear reactors. The methods, therefore, can include
dispensing independent pulses of gases linearly over first and
second regions of a workpiece. Several embodiments of the invention
may also be used in other geometries according to the shape of the
reactor and the gas distributor. Accordingly, the invention is not
limited except as by the appended claims.
* * * * *