U.S. patent application number 11/255288 was filed with the patent office on 2006-02-23 for semiconductor fabrication methods and apparatus.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Terry L. Gilton, Li Li.
Application Number | 20060040506 11/255288 |
Document ID | / |
Family ID | 32926103 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060040506 |
Kind Code |
A1 |
Gilton; Terry L. ; et
al. |
February 23, 2006 |
Semiconductor fabrication methods and apparatus
Abstract
Methods and apparatus for fabricating and cleaning in-process
semi-conductor wafers are provided. An in-process wafer is placed
within a closed chamber. A reactant gas is incorporated in a liquid
solvent to form a "reactant mixture" that is capable of reacting
with photoresist material for other material) on a wafer surface to
facilitate removal of the material from the wafer surface. The
reactant mixture is condensed on one or more of the in-process
wafer surfaces to form a thin film on the surface(s) of the wafer.
The solvent in the reactant mixture acts as a transport medium to
place the reactant gas on the wafer surface. The reactant gas is
then able to react with the photoresist material (or other
material) on the in-process wafer surface to effect removal the
material. Following reaction of the reactant gas with the
photoresist, the thin film of reactant mixture is removed from the
wafer surface by flash heating, rinsing, draining, or other
suitable means.
Inventors: |
Gilton; Terry L.; (Boise,
ID) ; Li; Li; (Meridian, ID) |
Correspondence
Address: |
KLARQUIST SPARKMAN, LLP
121 SW SALMON STREET
SUITE 1600
PORTLAND
OR
97204
US
|
Assignee: |
Micron Technology, Inc.
|
Family ID: |
32926103 |
Appl. No.: |
11/255288 |
Filed: |
October 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09579345 |
May 25, 2000 |
6979653 |
|
|
11255288 |
Oct 20, 2005 |
|
|
|
09321518 |
May 27, 1999 |
6790783 |
|
|
09579345 |
May 25, 2000 |
|
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|
Current U.S.
Class: |
438/745 ;
257/E21.255 |
Current CPC
Class: |
G03F 7/423 20130101;
H01L 21/31133 20130101; H01L 21/6708 20130101; H01L 21/31138
20130101 |
Class at
Publication: |
438/745 |
International
Class: |
H01L 21/302 20060101
H01L021/302 |
Claims
1-15. (canceled)
16. A method for semiconductor wafer fabrication, the method
comprising: selecting a liquid solvent that is inert to a material
on a surface of a wafer; forming a mist of liquid solvent droplets
above the surface of the wafer; selecting a reactant gas that is
capable of chemically reacting with the material on the surface of
the wafer and exposing the reactant gas to the liquid solvent
droplets; forming, on the surface of the wafer, a film of the
liquid solvent and exposing the film to the reactant gas so that
the reactant gas is transported through the film to the material on
the surface of the wafer; and cooling the wafer to a temperature
equal to or less than about a dew point of the liquid solvent.
17. (canceled)
18. The method of claim 16, wherein only one reactant gas is
used.
19. The method of claim 16, wherein the film has a thickness of
from about 1 micron to about 100 microns.
20-25. (canceled)
26. A method of semiconductor fabrication, the method comprising:
selecting a liquid solvent that is inert to a material on a surface
of a wafer; selecting a reactant gas that is capable of
chemically-reacting with the material on the surface of the wafer
and incorporating the reactant gas into the liquid solvent;
showering the liquid solvent incorporating the reactant gas onto
the surface of the wafer and exposing the liquid solvent to the
reactant gas so that the reactant gas chemically reacts with the
material on the surface of the wafer; and controlling the
temperature at or near the surface of the wafer so that the
temperature at or near the surface of the wafer is less than the
temperature of the showering liquid solvent.
27. The method according to claim 26, wherein the exposing step
comprises exposing a film of the liquid solvent to the reactant gas
while the film is on the wafer surface.
28. The method of claim 26, wherein the wafer is at a temperature
equal to about 25.degree. C. and the liquid solvent is at a
temperature equal to about 90.degree. C.
29. The method of claim 26, wherein the wafer is supported in a
vertical position relative to the shower of liquid solvent.
30-31. (canceled)
32. A method for removing photoresist material from a semiconductor
wafer, the method comprising: selecting a liquid that does not
chemically react with photoresist material; cooling the wafer:
forming a layer of the liquid on a surface of the wafer having
photoresist material thereon; introducing ozone gas over the layer
of liquid such that some of the flowing ozone gas is transported
through the layer of liquid to the surface of the wafer; and
reacting the ozone gas transported to the surface of the wafer with
the photoresist material on the wafer surface.
33. The method of claim 32, wherein the ozone gas is introduced
prior to the formation of the layer of liquid.
34. The method of claim 32, wherein the ozone gas is introduced
simultaneously with the formation of the layer of liquid.
35. The method of claim 32, wherein the ozone gas is introduced
after the formation of the liquid layer.
36. The method of claim 32 in which the liquid layer is less than
about 100 microns thick over the majority of the wafer surface
containing the liquid layer.
37-46. (canceled)
Description
FILED OF THE INVENTION
[0001] The present invention relates to the field of semiconductor
device fabrication and wafer cleaning.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] During the processing of semiconductor wafers used in
manufacturing integrated circuits and the like, it is typically
necessary to remove chemicals or residues from the wafer surface.
For example, it is sometimes necessary to etch openings or other
geometries into a thin film deposited onto (or grown on) the
surface of a wafer substrate. (The wafer substrate typically
comprises silicon, gallium arsenide, glass, an insulating material
such as sapphire, or any other substrate material upon which an
integrated circuit wafer may be fabricated.) Present methodology
for etching such a thin film requires that the film be exposed to a
chemical etching agent to remove desired portions of the film or
films. The composition of the etching agent used to remove the
portion of the film depends upon the nature of the thin film.
[0003] In order to ensure that only desired portions of the thin
film are removed, a photolithography process is use by which a
pattern is transferred to the surface of the thin film. The pattern
serves to identify the areas of the thin film that are to be
selectively removed. The pattern is typically formed with a
photoresist material, typically a light-sensitive material that is
spun onto the in-process integrated-circuit wafer also in the form
of a thin film. The thin film of photoresist is then exposed to a
high intensity light source that is projected through a photomask.
The photomask defines a desired pattern. As the light source is
projected through the photomask, the desired pattern is defined on
the photoresist thin film. The exposed or unexposed photoresist,
depending upon the polarity of the photoresist material, is
dissolved (i.e., is removed or stripped) with developers, leaving a
pattern that allows etching to take place in the selected areas
only.
[0004] Some of the current methods for stripping the photoresist
(or other materials, such as dry-etch residues or polymers) include
a hot chemical removal with a chemical etching agent. Sulfuric acid
and hydrogen peroxide or dry reactive removal, known as photoresist
ashing are typical removal methods. The hot chemical removal
methods are undesirable in that they involve great expense due to
the relatively large amount of chemical etching agent needed and
require expensive disposal methods due to the caustic nature of the
chemical etching agents. The ashing method is undesirable in that
it involves a high-energy gas and often incurs damage to the wafer
substrate or the layers of thin films formed on the wafer substrate
to make the wafer integrated circuits.
[0005] Some chemicals in the gaseous phase may react with
photoresist material or other such materials to facilitate removal
of the materials from the wafer surface. Many of such gases,
however, do not have effective transport means to the wafer surface
to effect the necessary reaction in a reasonable period of time.
Also, many such gases are too unstable to be introduced to the
wafer in an atmosphere filled with such gas and effect the
necessary reaction with the photoresist material. Such gases
typically have short half-lives and change in structure in such
environments so quickly that the gas is unable to react with a thin
film material on the surface of a wafer. Many such gases (both the
unstable gases and those lacking sufficient
transport-characteristics), however, are sufficiently soluble in a
variety of liquid solvents.
[0006] For example, there has been a current interest in the use of
ozone (i.e., O.sub.3) as a photoresist etching agent for the
stripping of photoresist, dry etch residues/polymers, and the like
from a wafer surface. Ozone reacts with photoresist material on the
wafer surface to oxidize the photoresist (forming CO.sub.2). Ozone,
however, is an unstable gas and will decompose before reacting with
the wafer surface photoresist material if simply introduced in its
gaseous state. Accordingly, a solvent is used to dissolve the ozone
and transport the ozone to the wafer surface such that the ozone
may react with the photoresist material and strip the photoresist
material from the wafer surface.
[0007] Water may act as a solvent to dissolve ozone. One method for
use of ozone as a stripping agent involves immersing the in-process
wafer into a water bath through which ozone is bubbled. It is
difficult, however, to get a sufficient amount of ozone dissolved
in the water to affect the desired oxidation reactions. Further,
the amount of ozone transported to the wafer surface is limited due
to the large amount of water filling the bath. Consequently, the
stripping process is very slow.
[0008] Without being tied to any particular theory, it is believed
that a main barrier to dissolution of the gas into water is kinetic
in nature. Another method calls for chilling a water bath and using
a diffusion plate in the water to bubble ozone gas therethough. The
diffusion plate creates numerous tiny bubbles that rise through the
water. The wafers are then immersed in the water bath. During this
residence time, the gas dissolves in the liquid by crossing the
gas/liquid interface so that the ozone in the water strips the
photoresist (or other material) on the wafer. Other methods for
dissolving the gas into the liquid (e.g., water) include the use of
static mixing devices and membrane contactors.
[0009] This method, however, relies heavily on the configuration
and performance of the diffusion devices (e.g., the diffusion plate
in the water bath) and requires long time periods of exposure of
the gas to the water. The increased time and the need for diffusion
apparatus add undesirable time and complexity to the process.
Further, the photoresist stripping effectiveness of such processes
is limited, as discussed above, as only a small amount of ozone
moves to (i.e., has physical contact with) the surface of the wafer
while the wafer is immersed in the water bath.
[0010] Accordingly, methods and apparatus are needed to fabricate
and/or clean wafers without incurring the expense and apparatus
complexity encountered with the prior art methods and apparatus.
Additionally, methods and apparatus are needed that provide
effective stripping of photoresist, dry etch residues/polymers, or
the like in a reasonably short lime period. Further, methods and
apparatus are needed that can overcome the kinetic limitation to
dissolution of a gas in a liquid without the need for long exposure
times of the gas to the liquid.
[0011] To overcome the disadvantages of the prior art, methods and
apparatus are disclosed herein. The methods and apparatus provided
eliminate the need for large amounts of caustic chemical cleaning
agents to remove photoresist, dry etch residues/polymers, or the
like. The methods and apparatus provided also require only a
relatively small amount of gas and liquid to strip the photoresist,
dry-etch residues/polymers, or the like. Additionally, the methods
and apparatus overcome the kinetic limitation of dissolution of the
gas in the liquid without requiring long exposure times of the gas
to the liquid. Further, the methods and apparatus provide a liquid
solvent that effectively transports the reactant gases that most
effectively and quickly strip photoresist material (or other
material) from a wafer surface. The liquid solvent, however, does
not react with materials on the wafer surface, but merely acts as a
transport medium to put the reactant gas in physical contact with
the wafer surface.
[0012] More specifically, an in-process wafer is placed in a
chamber, preferably a chamber of low volume. A liquid solvent
(e.g., water) incorporates (e.g., dissolves) a reactant gas (e.g.,
ozone) to create a "reactant mixture." The reactant gas in the
mixture will react with and remove photoresist material for other
material) on the wafer surface. In one representative method, the
reactant mixture enters the chamber and forms a thin film on one or
more surfaces of the wafer. The chamber preferably includes a
reactant gas atmosphere during and/or after formation of the thin
film. The solvent acts as a transport medium to place the reactant
gas in direct physical contact with the wafer surface. The reactant
gas is then able to react with the photoresist material (dry etch
residue/polymer or the like) on the in-process wafer surface to
effect removal of the material. The solvent does not react with the
photoresist material (or other material at issue) to be removed nor
with the reactant gas. The solvent acts merely to transport a
sufficient amount of the reactant gas to the wafer surface such
that the gas reacts with the photoresist material to effect
removal.
[0013] For example, ozone (i.e., a reactant gas for conventional
photoresist material) dissolves in water (i.e., an ozone solvent or
"transport medium") to form a reactant mixture. The reactant
mixture condenses to form a thin layer on one or more wafer
surfaces. The ozone reacts with the photoresist to form CO.sub.2.
The water does not react with the photoresist (or the ozone), but
merely transports a sufficient amount of the ozone gas to the wafer
surface so that the ozone gas reacts with the photoresist to effect
removal in a relatively short period of time. Following reaction
with the photoresist, the layer of reactant mixture is removed from
the wafer surface by flash heating, rinsing, drained, or other
suitable removal method.
[0014] In the representative methods and apparatus, the reactant
mixture condenses or otherwise collects on the wafer surface to
form a thin film thereon. The high surface area to volume ratio of
the thin film reactant mixture results in transport of a relatively
high volume or concentration of reactant gas directly onto the
wafer surface. Accordingly, the removal of photoresist (or the
like) from the wafer surface occurs relatively rapidly. The methods
and apparatus allow the removal process to be carried out in a low
volume chamber requiring a minimal amount of reactant gas and
solvent. Additionally, both the reactant gas and the solvent may be
purified and re-circulated during the wafer fabrication process,
thereby wasting little chemical and having little chemical waste
for which disposal is necessary.
[0015] The foregoing features and advantages of the methods and
apparatus will become more apparent from the following detailed
description of representative methods and apparatus that proceed
with reference to the accompanying drawings. The present invention
is directed toward novel and non-obvious features and advantages of
the disclosed methods/apparatus for fabricating and cleaning
in-process wafers, both individually and collectively, as set forth
above and additionally as set forth in the drawings and description
following.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a partial cross-sectional view of an in-process
wafer.
[0017] FIG. 2 is a cross-sectional view of a closed reaction
chamber including in-process wafers therein which wafers
are-undergoing one step of a photoresist stripping method.
[0018] FIG. 3 is a general block diagram of a photoresist stripping
system.
[0019] FIG. 4 is a flow diagram illustrating a number of
representative methods.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Methods and apparatus for removing photoresist material, dry
etch residues/polymers, and like materials from an in-process
wafer, are provided. For ease of discussion, the methods and
apparatus are primarily discussed in terms of the stripping of
photoresist from an in-process wafer surface. It should be
understood that the methods and apparatus may be used to remove a
variety of materials and residues from wafer surfaces and are not
limited to the stripping of photoresist material. Further, reactant
gases and liquid solvents useful for practicing the methods are
primarily discussed in terms of ozone in water. It should be
understood that a variety of reactant gases (including mixtures of
gases) and liquid solvents (as discussed below) may be use to
practice the invention.
[0021] In general, an in-process wafer is placed within a chamber.
A reactant gas is incorporated into a solvent (for example, the
liquid solvent may dissolve the reactant gas) to form a "reactant
mixture" that is capable of reacting with the photoresist material
to facilitate removal of the photoresist material from the wafer
surface.
[0022] A number of the representative methods are illustrated in
outline form in FIG. 4. In one representative method, the reactant
mixture enters the chamber in the vapor phase. A vapor is a gas at
a temperature below the critical temperature. The vapor phase
reactant mixture condenses on one or more of the in-process wafer
surfaces to form a thin film or layer on the surface(s) of the
wafer. The solvent acts as a transport medium to place the reactant
gas on the wafer surface(s). The reactant gas is then able to react
with the photoresist material on the in-process wafer surface to
effect removal of the material. Following reaction of the reactant
gas with the photoresist, the condensed reactant mixture is removed
from the wafer surface by flash heating, rinsing, draining, or
other suitable method. The process preferably takes place in a
reactant gas atmosphere. Alternatively, preferably the process
includes flowing a stream of reactant gas over the thin film.
[0023] More specifically, a first representative method includes
stripping photoresist material from an upper surface of an
in-process wafer, such as the wafer shown in FIG. 1. A typical,
in-process wafer 12 is being formed on a substrate 14, such as a
silicon substrate. A film 16 is deposited on the substrate 14. A
layer of photoresist material 18 is applied on film 16. The
photoresist material 18 is exposed and developed, patterning
openings 20. Openings 20 allow subsequent, selective etching of
film 16. The photoresist material 18 then needs to be stripped from
the in-process wafer 12.
[0024] Accordingly, in a first method, in-process wafers 12 are
placed into a chamber 10 of an apparatus such as is shown in FIG.
2. The embodiment of the reaction chamber 10 shown in FIG. 2
includes in-process wafers 12 positioned on the interior 26 of the
chamber. The in-process wafers 12 are, preferably placed in a boat
24 that supports the wafers in a vertical position. Alternatively,
a boat or other holder may support the wafers 12 in a horizontal
position, or any other position that allows access to the surface
of the wafer 12 to be treated.
[0025] Chamber 10 is preferably closed to form a controlled
environment such that its contents are not exposed to the ambient
atmosphere. Thus, contaminants, such as oxygen, cannot contact the
surface of the in-process wafers 12. Alternatively, chamber 10 may
comprise a module (or separate modules) within a tool cluster. A
top chamber opening 28 communicates on an upstream side of the
chamber with a valve 30 and on a downstream side with the interior
26 of the chamber 10. Valve 30 is fluidly connected to a solvent
source 34 and to a reactant gas source 38. Solvent source 34 may
comprise, e.g., a boiler. A bottom chamber opening 40 fluidly
communicates with a drain 44 that is connected to a
re-circulation/purification device, as discussed below. A gas
outlet is located at the bottom of the chamber. A temperature
controller, for controlling the temperature of the interior 26 of
the chamber and/or the wafers 12 in the chamber is connected
thereto.
[0026] A reactant gas (e.g., ozone) is then dissolved in a liquid
solvent (e.g., water). The reactant gas comprises a gas or a
mixture of gases capable of reacting directly with the photoresist
material (or other material) on an in-process wafer surface to
remove the photoresist material therefrom. Typically, the reactant
gases are unstable unless dissolved in a solvent. The gases also
include those gases that are stable but are not transported
effectively in sufficient concentration to a wafer surface because
the gas molecules do not remain in physical contact with the wafer
surface long enough to react with the photoresist material
thereon.
[0027] The solvents are those liquids that dissolve or otherwise
incorporate a suitable concentration of the reactant gas. The
solvents also are capable of forming a film of liquid (or
condensate) on a wafer surface. For example, most any
perfluorocarbon will dissolve the reactant gas ozone. The solvent,
however is merely a transport medium for the reactant gas and does
not react with the photoresist material (or other material) on the
wafer surface. The solvent may comprise a single solvent or a
mixture of solvents.
[0028] In the first method, the reactant gas is first dissolved in
the solvent to form a "reactant mixture." The reactant mixture is
vaporized (i.e., volatilized) and introduced to the chamber 10
through upper chamber opening 28. In such a case, the solvent
source 34 also includes a dissolved gas in the solvent. The
concentration of the gas in the solvent is preferably at least from
about 10% to about 95% gas to solvent by volume. In general, the
concentration of the reactant gas in the solvent should be as high
as possible because higher reactant gas concentrations strip the
photoresist material more quickly than do reactant mixtures having
lower reactant gas concentrations.
[0029] The vaporous reactant mixture enters the interior 26 of the
chamber 10 to condense on one or both surfaces of the in-process
wafer 12 to form a film or layer thereon. To ensure the vaporous
reactant mixture condenses to form a film or layer on the
in-process wafer 12, the wafer may be cooled to a temperature equal
to about the dew point of the solvent. At such a temperature, a
thin film of the reactant mixture will form on one or more wafer
surfaces. Alternatively, the wafer 12 may be at ambient
temperature, but with ambient temperature being a temperature that
is lower than the temperature of the reactant mixture. Good results
are achieved when the wafer is at a temperature of about 10.degree.
C. lower than the temperature of the reactant mixture. Under such
conditions, the reactant mixture condenses on one or more of the
wafer surfaces. The wafer preferably is not cooled to a temperature
that would freeze the solvent as freezing may interfere with the
transport characteristics of the solvent.
[0030] In the representative methods, the film or layer of reactant
mixture formed on the in-process wafer 12 surface(s) is preferably
from about 1 .mu.m to about 100 .mu.m in thickness. At a higher
thickness, the reaction process slows. A thin film of about 2000
.mu.m to about 3000 .mu.m in thickness tends to cause a relatively,
slow reaction process (likely to be about ten times slower than
that of a thin film having a thickness of about 100 .mu.m). The
reaction time is also slower at lower temperatures, as would be
expected.
[0031] The reactant gas in the thin film reactant mixture reacts
with the photoresist (or other material) in a relatively short
time. Typically, the reactant gas sufficiently reacts with the
photoresist material in about five minutes for a thin film layer
having a thickness of about 100 .mu.m and a reactant gas
concentration of about 10 percent gas by volume. If the thin film
is thicker, the reaction time period is longer to ensure sufficient
removal of the photoresist.
[0032] In the first method (as well as the representative methods
discussed below), the process preferably takes place in an
atmosphere of reactant gas. Alternatively, preferably the process
includes flowing a reactant gas stream over the film or layer.
[0033] Following reaction of the reactant gas with the photoresist
(or other material to be removed), the reactant mixture thin film
is removed. The reactant mixture thin film material is removed from
the wafer surface(s) by heating the wafer or heating the wafer
environment (preferably in hot nitrogen gas). Alternatively, the
reactant mixture thin film material may be removed by rinsing the
wafer 12, allowing the thin film to drip off the wafer 12, or any
other suitable manner (dependent upon the nature of the wafer at
issue).
[0034] In a second representative method, the reactant mixture is
introduced to the interior 26 of the chamber 10 in the liquid phase
by a nebulizer 32 in the chamber 10. The nebulizer 32 may comprise
an ultrasonic nebulizer or any other suitable device for forming a
fine mist of the reactant mixture. The nebulizer 32 creates a fine
mist of tiny reactant mixture droplets. The droplets may be of any
suitable size to condense on and form a thin film on the surface of
an in-process wafer 12. In one embodiment, the nebulizer 32
produces reactant mixture droplets at about the Meinhardt droplet
size (i.e., about 10 .mu.m to about 50 .mu.m). A nebulizer mist
reactant mixture then condenses on one or more of the wafer 12
surfaces. At this point, the second method follows the method
outlined above in relation to the first method (see FIG. 4).
[0035] In a third method, the reactant mixture enters the chamber
10 through a shower device 46 positioned at upper chamber opening
28 of the reactant mixture. The reactant mixture is not in a vapor
phase, but "drips" in the liquid phase from the shower device 46 to
the vertically positioned in-process wafers 12. The dripping
reactant mixture forms a thin film on the surface of the wafer 12.
With such a method, a thicker layer of reactant mixture tends to
form on the lower portion of the vertically positioned wafer (due
to gravity).
[0036] To ensure the desired thin film layer thickness over the
entire wafer surface, a hydrophilic material may be put in physical
contact with the lower portion of the wafer to remove excess
reactant mixture therefrom (thereby ensuring a thin film of
suitable thickness remains on the wafer surface). Alternatively,
the excess reactant mixture may be allowed to simply drip off of
the wafer surface. A thinner film is desirable however, as the
thinner film enables a quicker reaction of the reactant gas with
the photoresist material, thereby increasing production throughput.
When using the shower apparatus to form a thin film of the reactant
mixture on a wafer surface, the wafer is preferably at a
temperature equal to about 25.degree. C. while the reactant mixture
is preferably at a temperature equal to about 90.degree. C. At this
point, the third method follows the method outlined above in
relation to the first method (see FIG. 4).
[0037] Referring to FIG. 3, in a fourth representative method, a
reactant gas from gas source 52 is dissolved in a solvent from
solvent source 56 to form a reactant mixture. The reactant mixture
is then introduced to a chamber 62 via valve assembly 30. Valve
assembly 30 may include a boiler 36 connected to the solvent source
26. Chamber 62 is preferably a closed chamber for the reasons
discussed above in relation to the chamber 10 apparatus. An
in-process wafer 12 is mounted on a spinner device 66. As the
reactant mixture enters the chamber 62, the mixture is condensed on
the wafer surface 68. The reactant mixture may pass through a
mister or nebulizer 42 to form a mist of reactant mixture droplets.
A film of reactant mixture is formed on the surface. The reactant
mixture may be spun onto the wafer surface using any conventional
spinner device, such as the spinner shown in FIG. 3 but this is not
a preferred method. The speed of rotation of the wafer 12 would be
used to control the thickness of the thin film of reactant mixture
formed on the wafer surface 68. At this point, the fourth method
follows the method outlined above in relation to the first
method.
[0038] Referring back to FIG. 2, in a fifth representative method,
the reactant gas from reactant gas source 38 is introduced to the
chamber 10 simultaneously with the solvent from the solvent source
34. The solvent is introduced to the chamber 10 in the vaporous
phase (or liquid phase) such that the reactant gas dissolves in the
solvent to form the reactant mixture while in the chamber 10. The
reactant mixture then condenses or otherwise forms on the wafer
surface, to form a thin film thereon. The rest of the fifth method
is carried out as described above in relation to method one (see
FIG. 4).
[0039] In a sixth representative method, the solvent is vaporized
and then condensed on the wafer 12 to form a film thereon. The
liquid solvent need not be vaporized but may form a layer or film
on the wafer by any suitable means (e.g., nebulizing, showering,
etc.). The film of solvent is then exposed to an atmosphere of the
reactant gas within the chamber 10. The reactant gas dissolves in
the film of solvent and reacts with the photoresist (or other
material) on the wafer. The rest of the sixth method is carried out
as described above for the first method (see FIG. 4).
[0040] Lastly, in each of the methods described above, following
removal of the reactant mixture thin film (along with removal of
any residual photoresist or other material) the reactant mixture is
drained through lower chamber opening 40 to a drain 44. Drain 44
may be connected to a re-circulation/purification device 50 wherein
the gas and solvent are purified and re-circulated to be used for
the next batch of wafers.
[0041] Whereas the invention has been described with reference to
multiple embodiments of the apparatus and representative methods,
it will be understood that the invention is not limited to those
embodiments. On the contrary, the invention is intended to
encompass all modifications, alternatives, and equivalents as may
be included within the spirit and scope of the invention as defined
by the appended claims. For example, to form a layer or thin film
of solvent or reactant mixture on the wafer surface, the wafer may
be dipped into a container of the respective liquid.
* * * * *