U.S. patent application number 10/614244 was filed with the patent office on 2004-05-27 for resist film removal apparatus and resist film removal method.
Invention is credited to Miki, Nobuhiro, Nitta, Takahisa.
Application Number | 20040099284 10/614244 |
Document ID | / |
Family ID | 27761608 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040099284 |
Kind Code |
A1 |
Miki, Nobuhiro ; et
al. |
May 27, 2004 |
Resist film removal apparatus and resist film removal method
Abstract
A line slit nozzle for spraying steam is disposed along a
diameter of a resist film. Steam containing a mist is sprayed onto
a surface of the resist film. The film is thereby peeled off and
removed. By using a change in physical properties (swelling, etc.)
of the resist film by water, the film is easily and surely peeled
off. Breakaway from much resources/energy consumption type
techniques is realized. In other words, realized are
environment-symbiosis type techniques by which resist films can be
removed independently of the quantity of energy and kinds of
chemical solvents.
Inventors: |
Miki, Nobuhiro; (Tokyo,
JP) ; Nitta, Takahisa; (Tokyo, JP) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Family ID: |
27761608 |
Appl. No.: |
10/614244 |
Filed: |
July 8, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10614244 |
Jul 8, 2003 |
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09636821 |
Aug 14, 2000 |
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6610168 |
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09636821 |
Aug 14, 2000 |
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09416416 |
Oct 12, 1999 |
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Current U.S.
Class: |
134/1.3 ;
134/153; 134/198; 430/328; 430/329 |
Current CPC
Class: |
B08B 2230/01 20130101;
Y10T 156/11 20150115; B08B 2203/0288 20130101; B08B 3/00 20130101;
G03F 7/422 20130101; G03F 7/427 20130101; B08B 7/0057 20130101;
B08B 3/02 20130101; H01L 21/6715 20130101; Y10T 156/1116 20150115;
Y10T 156/1121 20150115 |
Class at
Publication: |
134/001.3 ;
430/328; 430/329; 134/198; 134/153 |
International
Class: |
B08B 003/00; B08B
007/00; G03F 007/40; B08B 003/12; G03F 007/42 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 1999 |
JP |
11-228917 |
Oct 12, 1999 |
JP |
11-325913 |
Dec 28, 1999 |
JP |
11-375228 |
Mar 10, 2000 |
JP |
2000-67782 |
Claims
What is claimed is:
1. An apparatus for removing a resist film used in a lithographic
process, said apparatus comprising: means for bringing steam into
contact with said resist film; and means for spraying steam onto
said resist film, wherein said resist film is peeled off by an
action of steam.
2. An apparatus as set forth in claim 1, wherein said resist film
is peeled off with saturated or superheated steam at a temperature
within the range of 70.degree. C. to 200.degree. C.
3. An apparatus for removing a resist film used in a lithographic
process, said apparatus comprising: means for spraying saturated
steam onto said resist film, wherein said resist film is peeled off
by an action of said saturated steam.
4. An apparatus as set forth in claim 3, wherein the temperature of
said saturated steam at the target surface is within the range of
70.degree. C. to 100.degree. C.
5. An apparatus as set forth in claim 1, wherein steam containing
an ingredient for promoting a change in quality of said resist film
is brought into contact with and/or sprayed onto a surface of said
resist film to peel said resist film.
6. An apparatus as set forth in claim 1, comprising a steam supply
system including a subsystem for generating steam, a subsystem for
heating steam, a subsystem for controlling the water quantity to be
supplied and the heat amount for heating, and a subsystem for
controlling the pressure of steam, said steam supply system being
connected to an ultrapure water supply line for selectively
supplying saturated or superheated steam at a temperature within
the range of 70.degree. C. to 200.degree. C.
7. An apparatus as set forth in claim 6, wherein said steam supply
system further includes a subsystem for switching lines between
said ultrapure water supply line and a line for a solution
containing an ingredient for promoting a change in quality of said
resist film, and an injecting pump for said ingredient, so that
steam containing said ingredient and steam not containing said
ingredient can be switched over.
8. An apparatus as set forth in claim 1, further comprising an
ultraviolet reactor including an ultraviolet lamp of a wavelength
corresponding to a transmissive distance of not less than 10 mm to
steam, said ultraviolet lamp being disposed in parallel with a
substrate surface on which said resist film is formed, so that said
substrate surface can be irradiated while and after said resist
film is peeled off said substrate surface by the action of
steam.
9. An apparatus as set forth in claim 1, further comprising a
chamber provided with a system for taking in a substrate on which
said resist film is formed and taking out said substrate off which
said resist film has been peeled, a system for purging an
atmosphere in said chamber, a system for discharging gas or liquid
from said chamber, a system for introducing steam into said
chamber, and a system for driving a steam spraying nozzle to move
relatively to the substrate surface on which said resist film is
formed, so as to sweep said substrate surface, said steam spraying
nozzle spraying steam onto said substrate surface to peel said
resist film off said substrate surface.
10. An apparatus as set forth in claim 9, wherein said chamber is
further provided with a system for supplying carbonic acid gas from
a gas bomb into said chamber, and a gas spraying nozzle for
spraying carbonic acid gas onto said substrate surface rapidly to
cool said resist film to be peeled off.
11. An apparatus as set forth in claim 7, further comprising a
supply line for a liquid chemical for cleaning a substrate,
connected to said steam supply system, wherein said substrate off
which said resist film has been peeled is cleaned by irradiation
with ultraviolet rays and spraying steam, and then dried by
spraying superheated steam.
12. An apparatus as set forth in claim 1, further comprising a
filter for filtering off pieces of said resist film having been
peeled off a substrate and contained in a liquid being discharged,
or a centrifugal separator for separating said pieces from said
liquid, wherein said liquid from which said pieces have been
removed is reused.
13. A method for removing a resist film used in a lithographic
process, said method comprising steps of: bringing saturated or
superheated steam into contact with said resist film; and spraying
saturated or superheated steam onto said resist film, wherein said
resist film is peeled off by an action of steam.
14. A method as set forth in claim 13, wherein steam containing an
ingredient for promoting a change in quality of said resist film is
brought into contact with a surface of said resist film to peel
said resist film.
15. A method for removing a resist film used in a lithographic
process, wherein saturated steam is sprayed onto said resist film,
and said resist film is peeled off by an action of said saturated
steam.
16. A method as set forth in claim 15, wherein the temperature of
said saturated steam at the target surface is within the range of
70.degree. C. to 100.degree. C.
17. A method as set forth in claim 13, wherein a substrate surface
on which said resist film is formed, is irradiated with excimer
ultraviolet rays of a wavelength corresponding to a transmissive
distance of not less than 10 mm to steam, while and after said
resist film is peeled off said substrate surface by the action of
steam.
18. A method as set forth in claim 13, wherein organic, metallic,
and granular contaminants are removed from a substrate surface off
which said resist film has been peeled, by spraying steam with
irradiating said substrate surface with ultraviolet rays, and then
said substrate surface is cleaned and dried by spraying steam.
19. A method as set forth in claim 13, wherein steam containing an
ingredient for promoting a change in quality of said resist film is
brought into contact with and/or sprayed onto a surface of said
resist film to peel said resist film.
20. An apparatus for removing a resist film used in a lithographic
process, said apparatus comprising: means for making steam act on
said resist film, wherein said resist film is peeled off by the
action of said steam.
21. An apparatus as set forth in claim 20, wherein said steam is
saturated steam, and the temperature of said saturated steam at the
target surface is within the range of 70.degree. C. to 100.degree.
C.
22. An apparatus as set forth in claim 20, wherein steam containing
an ingredient for promoting a change in quality of said resist film
is made to act on a surface of said resist film to be peeled
off.
23. An apparatus as set forth in claim 20, further comprising at
least one of: means for making water act on said resist film; means
for making vapor of isopropyl alcohol act on said resist film;
means for making compressed carbonic acid gas act on said resist
film; means for adding a chemical ingredient into said steam and/or
said water; means for irradiating said resist film with ultraviolet
rays; means for applying high-frequency supersonic waves to said
resist film; and means for cooling a substrate on which said resist
film is formed, wherein said resist film is peeled off by properly
combining at least one of time and/or spatial conditions,
conditions on temperature, and physical and/or chemical conditions
for operating each of said means.
24. A method for removing a resist film used in a lithographic
process, said method comprising: a step of making steam act on said
resist film, wherein said resist film is peeled off by the action
of said steam.
25. A method as set forth in claim 24, further comprising at least
one of: a step of making water act on said resist film; a step of
making vapor of isopropyl alcohol act on said resist film; a step
of making compressed carbonic acid gas act on said resist film; a
step of adding a chemical ingredient into said steam and/or said
water; a step of irradiating said resist film with ultraviolet
rays; a step of applying high-frequency supersonic waves to said
resist film; and a step of cooling a substrate on which said resist
film is formed, wherein said resist film is peeled off by properly
cross-combining at least one of time and/or spatial conditions,
conditions on temperature, and physical and/or chemical conditions
for performing each of said steps.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to apparatus and methods for
removing resist (photoresist) films, indispensable to
photolithographic processes for making minute structures of
semiconductor integrated circuits or the like.
[0003] 2. Description of the Related Art
[0004] As techniques for removing resist films, presently known are
ashing methods in which a resist film to be removed is ashed with
oxygen plasma, and heating and dissolving methods in which a resist
film to be removed is dissolved using an organic solvent, such as a
phenol- or halogen-base organic solvent, with being heated at 90 to
130.degree. C., or using concentrated sulfuric acid and hydrogen
peroxide. Any of these techniques requires a certain time, much
energy and a specific chemical material for decomposing or
dissolving the resist film. This was a strain on the
photolithographic process. In spite of a great demand for new
resist removing techniques to replace the above techniques by
ashing or dissolving, developments of peeling techniques are yet
few. As a representative of such peeling techniques, a new
technique has been developed in which a peeling liquid newly
developed and the peeling action of high-frequency supersonic waves
are used. As such a peeling liquid, the peeling action of "an
IPA-H.sub.2O.sub.2-base ingredient+salt such as fluoride" has bee
appreciated.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide resist
film removing apparatus and methods in which resist films can be
peeled off by using a change in physical properties and a change in
structure of the resist films due to application of steam and
ultraviolet rays, and thereby to realize breakaway from much
resources/energy consumption type techniques, that is, to realize
environment-symbiosis type techniques by which resist films can be
removed independently of the quantity of energy and kinds of
chemical solvents.
[0006] More specifically, the present invention is directed to
removal of resist films by using a change in physical properties,
such as softening, expansion, hydration, swelling, or
solidification, or a change in structure, such as cross-linking,
oxidation, or decomposition, of the resist films due to application
of steam and ultraviolet rays. Additive ingredients for promoting
such a change in quality may be selectively used.
[0007] In other words, the present invention is directed to removal
of resist films by a timely cross-combination, a spatially proper
cross-combination, a proper cross-combination on temperature, or a
chemically proper cross-combination of all or some of means for (or
process of) spraying steam, compressed water, or compressed
carbonic acid gas onto a resist film, means for (or process of)
adding a chemical ingredient to the steam or compressed water,
means for (or process of) heating or cooling the substrate holding
thereon the resist film, and means for (or process of) irradiating
the resist film with ultraviolet rays.
[0008] The present inventors have taken up the following elemental
techniques as subjects, and studied and developed them:
[0009] Change in quality of resist films by steam;
[0010] Chemical promotion of quality change of resist films;
and
[0011] Promotion of quality change of resist films by irradiation
with ultraviolet rays.
[0012] According to an aspect of the present invention, an
apparatus for removing a resist film used in a lithographic
process, comprises: means for bringing steam into contact with the
resist film; and means for spraying steam onto the resist film,
wherein the resist film is peeled off by an action of steam.
[0013] According to an aspect of the present invention, the resist
film is peeled off with saturated or superheated steam at a
temperature within the range of 70.degree. C. to 200.degree. C.
[0014] According to an aspect of the present invention, an
apparatus for removing a resist film used in a lithographic
process, comprises: means for spraying saturated steam onto the
resist film, wherein the resist film is peeled off by an action of
the saturated steam.
[0015] According to an aspect of the present invention, the
temperature of the saturated steam at the target surface is within
the range of 70.degree. C. to 100.degree. C.
[0016] According to an aspect of the present invention, steam
containing an ingredient for promoting a change in quality of the
resist film is brought into contact with and/or sprayed onto a
surface of the resist film to peel the resist film.
[0017] According to an aspect of the present invention, the
apparatus comprises a steam supply system including a subsystem for
generating steam, a subsystem for heating steam, a subsystem for
controlling the water quantity to be supplied and the heat amount
for heating, and a subsystem for controlling the pressure of steam.
The steam supply system is connected to an ultrapure water supply
line for selectively supplying saturated or superheated steam at a
temperature within the range of 70.degree. C. to 200.degree. C.
[0018] According to an aspect of the present invention, the steam
supply system further includes a subsystem for switching lines
between the ultrapure water supply line and a line for a solution
containing an ingredient for promoting a change in quality of the
resist film, and an injecting pump for the ingredient, so that
steam containing the ingredient and steam not containing the
ingredient can be switched over.
[0019] According to an aspect of the present invention, the
apparatus further comprises an ultraviolet reactor including an
ultraviolet lamp of a wavelength corresponding to a transmissive
distance of not less than 10 mm to steam. The ultraviolet lamp is
disposed in parallel with a substrate surface on which the resist
film is formed. The substrate surface can be irradiated while and
after the resist film is peeled off the substrate surface by the
action of steam.
[0020] According to an aspect of the present invention, the
apparatus further comprises a chamber provided with a system for
taking in a substrate on which the resist film is formed and taking
out the substrate off which the resist film has been peeled, a
system for purging an atmosphere in the chamber, a system for
discharging gas or liquid from the chamber, a system for
introducing steam into the chamber, and a system for driving a
steam spraying nozzle to move relatively to the substrate surface
on which the resist film is formed, so as to sweep the substrate
surface. The steam spraying nozzle sprays steam onto the substrate
surface to peel the resist film off the substrate surface.
[0021] According to an aspect of the present invention, the chamber
is further provided with a system for supplying carbonic acid gas
from a gas bomb into the chamber, and a gas spraying nozzle for
spraying carbonic acid gas onto the substrate surface rapidly to
cool the resist film to be peeled off.
[0022] According to an aspect of the present invention, the
apparatus further comprises a supply line for a liquid chemical for
cleaning a substrate, connected to the steam supply system, wherein
the substrate off which the resist film has been peeled is cleaned
by irradiation with ultraviolet rays and spraying steam, and then
dried by spraying superheated steam.
[0023] According to an aspect of the present invention, the
apparatus further comprises a filter for filtering off pieces of
the resist film having been peeled off a substrate and contained in
a liquid being discharged, or a centrifugal separator for
separating the pieces from the liquid, wherein the liquid from
which the pieces have been removed is reused.
[0024] According to an aspect of the present invention, a method
for removing a resist film used in a lithographic process,
comprises steps of: bringing saturated or superheated steam into
contact with the resist film; and spraying saturated or superheated
steam onto the resist film, wherein the resist film is peeled off
by an action of steam.
[0025] According to an aspect of the present invention, steam
containing an ingredient for promoting a change in quality of the
resist film is brought into contact with a surface of the resist
film to peel the resist film.
[0026] According to an aspect of the present invention, in a method
for removing a resist film used in a lithographic process,
saturated steam is sprayed onto the resist film, and the resist
film is peeled off by an action of the saturated steam.
[0027] According to an aspect of the present invention, the
temperature of the saturated steam at the target surface is within
the range of 70.degree. C. to 100.degree. C.
[0028] According to an aspect of the present invention, a substrate
surface on which the resist film is formed, is irradiated with
excimer ultraviolet rays of a wavelength corresponding to a
transmissive distance of not less than 10 mm to steam, while and
after the resist film is peeled off the substrate surface by the
action of steam.
[0029] According to an aspect of the present invention, organic,
metallic, and granular contaminants are removed from a substrate
surface off which the resist film has been peeled, by spraying
steam with irradiating the substrate surface with ultraviolet rays,
and then the substrate surface is cleaned and dried by spraying
steam.
[0030] According to an aspect of the present invention, steam
containing an ingredient for promoting a change in quality of the
resist film is brought into contact with and/or sprayed onto a
surface of the resist film to peel the resist film.
[0031] According to an aspect of the present invention, an
apparatus for removing a resist film used in a lithographic
process, comprises: means for making steam act on the resist film,
wherein the resist film is peeled off by the action of the
steam.
[0032] According to an aspect of the present invention, the steam
is saturated steam, and the temperature of the saturated steam at
the target surface is within the range of 70.degree. C. to
100.degree. C.
[0033] According to an aspect of the present invention, steam
containing an ingredient for promoting a change in quality of the
resist film is made to act on a surface of the resist film to be
peeled off.
[0034] According to an aspect of the present invention, the
apparatus further comprises at least one of: means for making water
act on the resist film; means for making vapor of isopropyl alcohol
act on the resist film; means for making compressed carbonic acid
gas act on the resist film; means for adding a chemical ingredient
into the steam and/or the water; means for irradiating the resist
film with ultraviolet rays; means for applying high-frequency
supersonic waves to the resist film; and means for cooling a
substrate on which the resist film is formed, wherein the resist
film is peeled off by properly cross-combining at least one of time
and/or spatial conditions, conditions on temperature, and physical
and/or chemical conditions for operating each of the means.
[0035] According to an aspect of the present invention, the
apparatus further comprises a one-by-one process chamber in which
substrates to be processed are disposed one by one. The chamber is
provided with a system for taking in and out the substrates, a
system for purging the atmosphere in the chamber, and a system for
discharging gas or liquid from the chamber, in addition to the
above means. The chamber is further provided with a driving system
for at least one of the means for making steam act on the resist
film, the means for making water act on the resist film, and the
means for making compressed carbonic acid gas act on the resist
film, to move relatively to the front or back surface of each
substrate.
[0036] According to an aspect of the present invention, as the
above time and/or spatial conditions for operating the above means
and/or the above systems, the order of the operations and the
intervals of the operations are properly cross-combined in relation
to the portions subjected to the operations, i.e., the surface of
the resist film, both or one of the front and rear surfaces of the
substrate, or part of the front or rear surface of the
substrate.
[0037] According to an aspect of the present invention, as the
above conditions on temperature for operating the above means
and/or the above systems, process temperatures and the raising and
lowering speeds thereof are properly cross-combined in relation to
the portions subjected to the operations, i.e., the surface of the
resist film, both or one of the front and rear surfaces of the
substrate, or part of the front or rear surface of the
substrate.
[0038] According to an aspect of the present invention, as the
above physical and/or chemical conditions for operating at least
one of the means for adding a chemical ingredient into the steam
and/or the water, the means for irradiating the resist film with
ultraviolet rays, and the means for applying high-frequency
supersonic waves to the resist film, the compositions of chemical
ingredients for the steam and/or the water, the frequencies of
supersonic waves, and the wavelengths of ultraviolet rays are
properly cross-combined.
[0039] According to an aspect of the present invention, the above
time and/or spatial conditions, the above conditions on
temperature, and the above physical and/or chemical conditions are
properly cross-combined with one another.
[0040] According to an aspect of the present invention, the means
for making steam act on the resist film has the function of
bringing the steam into contact with the resist film and the
function of spraying the steam onto the resist film. The contact
process and the spraying process are properly cross-combined.
[0041] According to an aspect of the present invention, the means
for making steam act on the resist film has the function of making
saturated steam act on the resist film and the function of making
superheated steam act on the resist film. The saturated steam
process and the superheated steam process are properly
cross-combined.
[0042] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and a
chemical ingredient composition determined by the means for adding
a chemical ingredient into the steam are properly
cross-combined.
[0043] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the water spraying process by the means for making water act on the
resist film are properly cross-combined.
[0044] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the ultraviolet irradiation process by the means for irradiating
the resist film with ultraviolet rays are properly
cross-combined.
[0045] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the high-frequency supersonic application process by the means for
applying high-frequency supersonic waves to the resist film are
properly cross-combined.
[0046] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the compressed carbonic acid gas spraying process by the means for
making compressed carbonic acid gas act on the resist film are
properly cross-combined.
[0047] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the cooling process by the means for cooling a substrate on which
the resist film is formed, are properly cross-combined.
[0048] According to an aspect of the present invention, the steam
process by the means for making steam act on the resist film, and
the vapor process by the means for making vapor of isopropyl
alcohol act on the resist film are properly cross-combined.
[0049] According to an aspect of the present invention, the
compressed carbonic acid gas spraying process by the means for
making compressed carbonic acid gas act on the resist film, and the
ultraviolet irradiation process by the means for irradiating the
resist film with ultraviolet rays are properly cross-combined.
[0050] According to an aspect of the present invention, by properly
cross-combining the above time and/or spatial conditions, the above
conditions on temperature, and the above physical and/or chemical
conditions for operating the above means and/or the above systems,
the substrate surface off which the resist film has been peeled is
processed to remove residues of the resist film and alien
substances. The substrate surface is thereby purified.
[0051] According to an aspect of the present invention, a method
for removing a resist film used in a lithographic process,
comprises a step of making steam act on the resist film, wherein
the resist film is peeled off by the action of the steam.
[0052] According to an aspect of the present invention, the method
further comprises at least one of: a step of making water act on
the resist film; a step of making vapor of isopropyl alcohol act on
the resist film; a step of making compressed carbonic acid gas act
on the resist film; a step of adding a chemical ingredient into the
steam and/or the water; a step of irradiating the resist film with
ultraviolet rays; a step of applying high-frequency supersonic
waves to the resist film; and a step of cooling a substrate on
which the resist film is formed, wherein the resist film is peeled
off by properly cross-combining at least one of time and/or spatial
conditions, conditions on temperature, and physical and/or chemical
conditions for performing each of the steps.
[0053] According to an aspect of the present invention, as the
above time and/or spatial conditions for performing the above
steps, the order of the steps and the intervals of the steps are
properly cross-combined in relation to the portions subjected to
the steps, i.e., the surface of the resist film, both or one of the
front and rear surfaces of the substrate, or part of the front or
rear surface of the substrate.
[0054] According to an aspect of the present invention, as the
above conditions on temperature for performing the above steps,
process temperatures and the raising and lowering speeds thereof
are properly cross-combined in relation to the portions subjected
to the steps, i.e., the surface of the resist film, both or one of
the front and rear surfaces of the substrate, or part of the front
or rear surface of the substrate.
[0055] According to an aspect of the present invention, as the
above physical and/or chemical conditions for performing at least
one of the step of adding a chemical ingredient into the steam
and/or the water, the step of irradiating the resist film with
ultraviolet rays, and the step of applying high-frequency
supersonic waves to the resist film, the compositions of chemical
ingredients for the steam and/or the water, the frequencies of
supersonic waves, and the wavelengths of ultraviolet rays are
properly cross-combined.
[0056] According to an aspect of the present invention, the above
time and/or spatial-conditions, the above conditions on
temperature, and the above physical and/or chemical conditions are
properly cross-combined with one another.
[0057] According to an aspect of the present invention, the step of
making steam act on the resist film includes a sub-step of bringing
the steam into contact with the resist film and a sub-step of
spraying the steam onto the resist film. The contact process and
the spraying process are properly cross-combined.
[0058] According to an aspect of the present invention, the step of
making steam act on the resist film includes a sub-step of making
saturated steam act on the resist film and a sub-step of making
superheated steam act on the resist film. The saturated steam
process and the superheated steam process are properly
cross-combined.
[0059] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and a
chemical ingredient composition determined in the step of adding a
chemical ingredient into the steam are properly cross-combined.
[0060] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
water spraying process by the step of making water act on the
resist film are properly cross-combined.
[0061] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
ultraviolet irradiation process by the step of irradiating the
resist film with ultraviolet rays are properly cross-combined.
[0062] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
high-frequency supersonic application process by the step of
applying high-frequency supersonic waves to the resist film are
properly cross-combined.
[0063] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
compressed carbonic acid gas spraying process by the step of making
compressed carbonic acid gas act on the resist film are properly
cross-combined.
[0064] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
cooling process by the-step of cooling a substrate on which the
resist film is formed, are properly cross-combined.
[0065] According to an aspect of the present invention, the steam
process by the step of making steam act on the resist film, and the
vapor process by the step of making vapor of isopropyl alcohol act
on the resist film are properly cross-combined.
[0066] According to an aspect of the present invention, the
compressed carbonic acid gas spraying process by the step of making
compressed carbonic acid gas act on the resist film, and the
ultraviolet irradiation process by the step of irradiating the
resist film with ultraviolet rays are properly cross-combined.
[0067] According to an aspect of the present invention, by properly
cross-combining the above time and/or spatial conditions, the above
conditions on temperature, and the above physical and/or chemical
conditions for performing the above steps, the substrate surface
off which the resist film has been peeled is processed to remove
residues of the resist film and alien substances. The substrate
surface is thereby purified.
[0068] According to the present invention, by using a change in
physical properties (such as swelling) of a resist film by steam
and a light decomposition effect by ultraviolet rays, it becomes
possible to peel off the resist film easily and surely. As a
result, breakaway from much resources/energy consumption type
techniques can be realized, that is, an environment-symbiosis type
technique independent of the quantity of energy and kinds of
chemical solvents can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] FIG. 1 is a schematic sectional view showing a portion near
a spraying nozzle of a resist removing apparatus according to the
present invention;
[0070] FIG. 2 is a graph showing the relation of the speed of
removing a resist film by steam containing KOH, to the
concentration of KOH;
[0071] FIG. 3 is a schematic view showing a principal construction
of a steam supply apparatus according to an embodiment of the
present invention;
[0072] FIG. 4 is a schematic view showing a principal construction
of a resist removal apparatus according to an embodiment of the
present invention;
[0073] FIGS. 5A to 5E are schematic sectional views showing the
constructions of samples from each of which a resist film is to be
peeled off; and
[0074] FIG. 6 is a schematic sectional view of a one-by-one resist
film removing apparatus including a spinning mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0075] Hereinafter, preferred embodiments of the present invention
will be described.
[0076] 1. Peeling Resist Film by Steam
[0077] Porousness and Hydrogen Bondability of Chemical Structure of
Resist Film:
[0078] In a photolithographic process for making a minute structure
of, e.g., a semiconductor integrated circuit, a resist film is
formed on a surface to be processed. Electromagnetic energy is then
applied to the resist film through fine pattern gaps provided on an
exposure mask. The thus formed pattern is developed in the resist
film by using the difference in solubleness to a solvent between
irradiated and non-irradiated portions of the resist film. The
surface to be processed is then etched using the resist film
pattern as an etching mask.
[0079] In such photolithographic processes, the wavelength of
ultraviolet rays used has gradually become shorter with progress of
the generations of degrees of integration. That is, g line, i line,
and ArF to F.sub.2 excimer lasers were used in this order. As a
matter of course, the chemical structures of resist films have been
reformed with shortening the used wavelength, and will be more
reformed for future X-ray and electron ray photolithography ages.
In reforming the chemical structures of resist films, it is
important to grasp the physical properties of the basic structures
unchanging fundamentally.
[0080] The present inventors have perceived the porousness and the
hydrogen bondability of the basic structures of the base polymers
of resist films.
[0081] Table 1 shows the basic structures of the base polymers of
various photoresists from an initial resist KPR to currently
mainstream resists, besides, resists for ARF excimer laser.
1TABLE 1 Base Polymer Basic Structure of Resist first generation
resist vinyl cinnamate 1 resist for g to i line cyclo-polyisoprene
2 do. novolac resin 3 resist for KrF polymethyl methacrylate 4 do.
polymethyl isopropenyl ketone 5 do. chloromethyl polystyrene 6 do.
polystyrene sulfone 7 do. polyvinyl phenol 8 resist for ArF
alicyclic polymethacrylate 9 do. polybutene sulfone -positive type-
10
[0082] The chemical structures of the principal and side chains of
these photoresists differ variously. But, in these various basic
structures, there are two fundamental points of sameness.
[0083] They are the porousness of the basic structures and the
hydrogen bondability of the constituent groups. Because of the
cyclic structures or the structures having side chains of, e.g.,
alicyclic groups or phenol groups, the polymer basic structures
have considerable spaces therein.
[0084] Besides, constituent groups having intensive hydrogen
bondability, such as phenol groups, carbonyl groups, or ester
groups, have been introduced. Introduction of these groups is
necessary for the resists sensitively to react to light energy.
Besides, resists must have solubility to developers, and the
porousness and hydrogen bondability are physical properties
necessary for the solubility.
[0085] Besides, the water permeabilities of resists are higher than
those of other organic polymers. For example, while the water
permeability
(Pa.multidot.cm.sup.3.multidot.s.sup.-1.multidot.m.sup.-2) of
Teflon, or polyethylene is about 3.times.10.sup.-11, those of
resists are 10.sup.-8 to 10.sup.-7, showing their structures more
permeable to water by three to four figures.
[0086] It is because the polymer structures of resists are porous
in contrast to compactness of organic polymers having structural
regularity, and further the polymer structures of resists have
hydrogen bondability.
[0087] In future, resists will be required to be chemically
amplificative, and addition of chemical amplification ingredients
will be done.
[0088] But, "resist-peeling" is directed by base polymer basic
structures. It is a characteristic feature of the present invention
to utilize the porousness and hydrogen bondability which are
fundamental properties of resists.
[0089] Change in Quality of Resist Film by Steam:
[0090] The present inventors has perceived the fact that the states
of resist films change rapidly and remarkably by steam. Physical
changes such as softening/expansion due to hot steam occur
naturally; besides, changes in physical properties such as
swelling/separation/solidification occur. There have been found
changes in chemical structure of the resist films though their
aspects vary in accordance with the kinds of resists and conditions
of steam. The details of such changes are supposed as follows.
[0091] Because the basic structures of the resist base polymers
have porousness as described above, the resist transmissivity of
steam is very high. A resist film is put in a pyrogenetic chemical
reaction system the moment it comes into contact with steam. It is
well known that the chemical action of water at a high temperature
is intensive, and there are known many instances of hydrolysis of
organic compounds by hot water. In a resist chemical structure,
side chains having high hydrogen-bondability and photosensitive
groups are present. Not only hydrolysis/oxidation of these groups
but also cross-linking in the resist basic structure
progresses.
[0092] Action of Saturated or Superheated Steam:
[0093] The temperature of steam necessary for processing a resist
film varies in accordance with the kind of resist and conditions of
the resist process. The steam temperature is selected to a suitable
value of 70.degree. C. to 200.degree. C. The temperature may be
more than 200.degree. C. if circumstances of the substrate allow.
In ultraviolet irradiation, superheated steam hardly brings about
absorption and scattering of ultraviolet rays due to a mist, and it
shows high efficiency of ultraviolet transmissivity. Besides,
superheated steam is not affected by the mist when drying the
surface from which a resist film has been peeled off.
[0094] Peeling Swelled Resist Film off Substrate by Spraying
Steam:
[0095] The power of sprayed steam acts effectively for peeling a
swelled resist film off a substrate. The resist film which has been
hydrated/swelled and softened by hot steam, a mist, and further a
swelling-promotion ingredient, is easily peeled off the substrate
surface if the linear velocity of sprayed steam is several m/sec to
scores m/sec. The peeling speeds depend on the kinds of resists. In
particular, ion-implanted resist films have a tendency to be hard
to peel off. Shape of pattern also exerts influence. In particular,
high aspect ratio is a cause of the tendency to be hard to peel
off. Considering such resist physical properties/substrate
structures, the linear velocity and spraying time are controlled.
In resist-peeling, it is important to control the spraying linear
velocity in order not to damage the minute structure of the exposed
surface.
[0096] Contact and Spraying of Steam:
[0097] Required is an apparatus capable of realizing a combination
of a step of bringing a resist film into contact with steam to
change the quality of the film, and a step of spraying steam onto
the resist film which has changed in quality, to peel off.
[0098] The surface structure exposed as a result of resist-peeling
must be protected without any damage. While the power of sprayed
steam at a linear velocity of one m/sec to scores m/sec is strong
and effective for resist-peeling, it may damage the device surface.
A two-step process is effective in which change in quality of a
resist film is made to progress in a contact step, and then the
film is peeled off in a spraying step of a short time. This is
suitable in particular for removing an ion-implanted resist film in
which the speed of change in quality is low, or a resist film on a
surface where a structural aspect ratio is high.
[0099] Resist-Peeling Only by Spraying Saturated Steam:
[0100] The present inventors have thought out a process of peeling
a resist film only by spraying steam containing droplets, i.e.,
saturated steam, without using the above-described two-step process
of the contact and spraying steps of steam.
[0101] More specifically, as shown in FIG. 1 for example, to remove
a resist film 44 after patterning a SiO.sub.2 film 43 on a
substrate 42, a steam spraying nozzle 41 is disposed to be opposed
to the resist film 44, and steam is sprayed to peel the resist film
44. In spraying conditions of this case, the temperature of
saturated steam at the portion which steam reaches, i.e., the
surface portion of the resist film 44, is controlled within the
range of 70.degree. C. to 100.degree. C., more preferably, within
the range of 75.degree. C. to 85.degree. C. This is because sprayed
steam makes saturated steam containing droplets, suitable for
peeling the resist film 44, at the surface portion of the resist
film 44 when the temperature is controlled within the above range.
FIG. 1 shows an example for realizing the above temperature range,
in which the distance from the spraying nozzle 41 to the surface of
the resist film 44 is 10 mm. Besides, the spraying pressure of
steam at the mouth of the spraying nozzle 41 is controlled to be
less than 10 kg/cm.sup.2, more preferably, within the range of 1 to
2 kg/cm.sup.2. If the pressure exceeds 10 kg/cm.sup.2, the spraying
nozzle 41 and device elements formed on the substrate 42 may be
adversely affected.
[0102] A process in which a contact step uses steam containing an
ingredient for promoting change in quality of a resist film as
described in the next section, and a spraying step uses pure water
steam, is effective for preventing a metal wiring surface from
being damaged.
[0103] Ingredient for Promoting Change in Quality of Resist:
[0104] It has been found that a change in physical
properties/structure by hot steam can be accelerated by making the
steam contain an ingredient for promoting the change in quality. In
particular, a resist film hardened by an ion-implantation process
is very hard to peel off. In spite of this fact, however, it can
rapidly be peeled off by using steam which contains a promotion
ingredient. Since the kind of effective promotion ingredient varies
in accordance with the kind of resist, it need be selected
individually. Protection of a structural substrate after
resist-peeling, e.g., chemical action on a metal surface of a metal
wiring substrate need be considered.
[0105] Oxidative substances are effective as promotion ingredients
for cross-linking or oxidation. For example, hydrogen peroxide can
make even an ion-implantation-processed resist film change in
quality/be peeled off in a short time. We suppose that it is by
oxidation of chemical bonding in the resist because of intensive
radical reaction. Ozone water is also effective as a promotion
ingredient for oxidation.
[0106] Also usable are other oxidative substances, such as
Cl.sub.2--H.sub.2O, Br.sub.2--H.sub.2O, I.sub.2--KI, NaClO,
NaClO.sub.4, KMnO.sub.4, K.sub.2CrO.sub.7, and
Ce(SO.sub.4).sub.2.
[0107] Alkali is a highly effective promotion ingredient. For
example, usable is an aqueous solution of caustic alkali at a pH
value of 8 to 14, more preferably, 10 to 12. It gives the resist
surface wettability/permeability, and makes the peeling-off action
rapid. As alkali, usable are KOH, NaOH, NaCO.sub.3, Ca(OH).sub.2,
Ba(OH).sub.2, NH.sub.4OH, TMAH, etc.
[0108] More specifically, examined were the removing speeds of
resist films which were used as a mask for ion implantation of
impurities (As), when the resist films were removed using the
technique shown in FIG. 1 and using KOH of alkali as a resist
quality change promotion ingredient. FIG. 2 shows the result of
measurement. In FIG. 2, the axis of abscissas represents the
concentration (wt. %) of KOH, and the axis of ordinates represents
the removing speed (sec). As shown in FIG. 2, the higher the KOH
concentration is, the higher the removing speed is. This shows that
the higher KOH concentration brings about the more efficient
resist-peeling. However, too high KOH concentration may cause an
adverse affection on a device material, so it is seemed that about
0.1 (wt. %) or less is proper.
[0109] Also acids and oxidative acids are promotion ingredients for
change in quality. For example, H.sub.2SO.sub.4 makes a resist
cross-link strongly. Usable are H.sub.2SO.sub.4, HNO.sub.3, HClO,
HClO.sub.4, HCl, HF, etc.
[0110] Surface active agents have interfacial osmotic actions and
surface functions for preventing peeled resist thin pieces from
again adhering to the surface which they have been peeled off. As
such surface active agents, usable are anionic, cationic, and
nonionic surface active agents whose contact angles to resist
surfaces are not more than 30 degrees, more preferably, not more
than 20 degrees.
[0111] 2. Peeling Resist Film by Ultraviolet Rays
[0112] (1) Decomposition of Resist Film by Ultraviolet Rays:
[0113] Table 2 shows experimental data of decomposition tests of
photoresists by ultraviolet rays. Light-decomposition of
photoresists is possible by using a Xe excimer lamp (wavelength:
172 nm) as an ultraviolet lamp. But, the decomposition speed is too
low to apply to removal of resist films. Although there is an
attempt of acceleration by existence of ozone at a high
concentration, putting it to practical use faces many hurdles.
2TABLE 2 Decomposition of Photoresist by Ultraviolet Rays ultra-
decrease speed violet in of theoretical irradia- film decom- speed
of tion thick- posi- decomposi- quantum time ness tion tion
efficiency photoresist (sec) (.mu.m) (nm/sec) (nm/sec) (%) positive
2700 700 0.26 0.12 47 type resist 1400 .mu.m thick Xe excimer light
source: wavelength of 172 nm; irradiation light quantity: 10
mW/cm.sup.2 on the outside of light source chamber window board
sample surface irradiation conditions: air layer between light
source and resist surface (distance = 2 mm) , surface temperature
of 80.degree. C.
[0114] The present inventors have perceived a change in quality of
resists by ultraviolet rays. It aims not at resist decomposition
but at resist-peeling. Since ultraviolet photons have strongly
promoting actions for cross-linking or oxidation, the action of
changing the quality of resists is intensive. An incorporated
effect with a quality-change effect by steam is used. Besides,
since ultraviolet rays have high resist transmissivity, they can
fully reach the boundary layer of resist/substrate. It is an
intensive permeating action. A change in quality of the boundary
layer is directly related to the peeling effect.
[0115] 3. Steam supply Apparatus
[0116] FIG. 3 shows the fundamental construction of a steam supply
apparatus. An evaporator 1 and a heating block 2 for generating
saturated steam, and a superheater 3 and a heating block 4 for
generating superheated steam, are disposed between a fixed flow
rate pump 5 and a pressure control needle valve 6. The internal
pressure of this steam generation system is measured with a
pressure gauge 7. The temperatures of saturated and superheated
steams are measured with thermometers 8 and 9, respectively. The
heating area in the evaporator 1 is so designed as to satisfy the
burnout point condition of a boiling characteristic curve.
[0117] Switching Between Steam of Pure Water and Steam Containing
Promotion Ingredient:
[0118] When steam of ultrapure water is generated, a valve 10 for
an ultrapure water line is opened. When steam containing a
promotion ingredient is generated, a valve 11 for an aqueous
solution line is opened.
[0119] Switching Between Saturated and Superheated Steams:
[0120] When saturated steam is supplied, the heating block 4 for
superheating is not supplied with heats. At this time, the
superheater 3 merely functions as a passage for steam. When
superheated steam is supplied, the heating block 4 is supplied with
heats to perform superheating by the superheater 3.
[0121] Switching Between Steam-Contact and Steam-Spraying:
[0122] When steam is introduced into a process chamber 15, an
introduction valve 12 is opened. When steam is sprayed onto a
surface to be processed, a steam-spraying valve 13 is opened and
steam is sprayed onto the surface 16 to be processed, through a
steam-spraying nozzle 14.
[0123] Table 3 exemplifies control conditions for steam supply.
Table 4 exemplifies conditions of the steam spraying nozzle. The
nozzle shape/steam quantity/spraying velocity can freely be
designed so as to meet the purpose.
3TABLE 3 Control Condition for Steam Supply saturated steam
generation superheated steam generation water supply conditions
conditions quantity and heat internal tempera- steam internal
tempera- steam quantity pressure ture quantity pressure ture
quantity ml/sec KWH Kg/cm.sup.2 .degree. C. L/sec Kg/cm.sup.2
.degree. C. L/sec 1.5 3.9 1.0 100 2.55 -- -- -- 1.5 3.9 2.0 120
2.69 1.00 120 2.69 1.5 4.0 3.6 140 2.83 1.00 140 2.83 1.5 4.0 6.0
160 2.96 1.00 160 2.96 water supply quantity temperature:
20.degree. C.; quantity of heat: net value (except radiation loss)
saturated steam: exemplified are only cases of 100 to 160.degree.
C. superheated steam: exemplified are only cases of 100.degree. C.
saturated superheated steam generation
[0124]
4TABLE 4 Condition Example of Steam-spraying Nozzle point nozzle
line slit nozzle steam- steam- spraying spraying steam linear
linear quantity velocity velocity L/sec nozzle shape m/sec nozzle
shape m/sec 2.55 inside 120 200 mm .times. 0.5 mm 52 diameter of 5
mm 2.55 inside 32 200 mm .times. 1.0 mm 13 diameter of 10 mm
[0125] 4. Ultraviolet Reactor
[0126] Selections of the ultraviolet wavelength and time
characteristics of a lamp used in an ultraviolet reactor are
important technical factors.
[0127] Selection of Ultraviolet Wavelength:
[0128] The shorter the ultraviolet wavelength is, the greater the
energy is and the lower the transmissivity to the irradiation
atmosphere is. The ultraviolet wavelength must be so selected as to
satisfy the objective transmissivity.
[0129] A relation between the light absorption sectional area of
molecules present in the atmosphere and the light transmissivity,
is given by expression (1). Logarithms of the transmissivity are
proportional to distances. The present inventors use 50%
transmissive distance as an index. This 50% transmissive distance
is given by expression (2). Table 5 shows relations between
ultraviolet wavelengths and 50% transmissive distances to air,
water, and steam obtained by expression (2) or actual measurements.
For example, the 50% transmissive distance of ultraviolet rays of
the wavelength of 172 nm to air is obtained as 3.1 mm from the
light absorption sectional area of oxygen (0.259.times.10.sup.-19
molecules/cm.sup.2) while the actual measurement of 2.2 mm was
obtained. Both are practically almost equal.
.delta.CL=ln(I.degree./I) (1)
[0130] .delta.: light absorption sectional area
(molecules/cm.sup.2), O.sub.2 . . . 0.259.times.10.sup.-19
[0131] C: molecule concentration (partial pressure of molecule)
[0132] L: transmissive distance (cm)
I.degree./I: light transmissivity=incident light
intensity/transmitted light intensity (2)
[0133] .delta.CL.sub.50=ln (100/50)
[0134] L.sub.50: 50% transmissive distance
5TABLE 5 Ultraviolet Wavelength and 50% Transmissive distances to
Air/Water/Steam 50% transmissive distance excimer wavelength energy
air water steam ultraviolet lamp nm eV mm mm mm Xe excimer lamp 172
7.21 3 -- ArCl excimer lamp 175 7.08 6 <10 <10 185 6.70 40 10
>1 .times. 10.sup.4 KrI excimer lamp 191 6.49 100 28 ArF excimer
lamp 193 6.42 >100 42 KrBr excimer lamp 207 5.99 >100 KrCl
excimer lamp 222 5.58 low pressure 185 .cndot. 254 mercury lamp
i-line lamp 365 3.41
[0135] Selection of Time Response:
[0136] An ultraviolet lamp is selected in accordance with the type
of ultraviolet process, i.e., which of a moment type and a constant
type is performed.
[0137] An ultraviolet excimer lamp can be used in a moment-type
process. It reaches its stationary state in several seconds after
being lit.
[0138] It is suitable for a sequential process in seconds in a
one-by-one ultraviolet process. A low pressure mercury lamp, an
i-line lamp, or the like, can be used in a constant-type process.
Although they require scores minutes for reaching their stationary
states after being lit, they are stable after then.
[0139] 5. One-by-One Resist-Peeling Apparatus
[0140] (1) Construction of Apparatus:
[0141] A one-by-one resist-peeling apparatus comprises a steam
process chamber and an ultraviolet lamp chamber.
[0142] The steam process chamber has a substrate taking-in/out
system, an atmosphere purge system, and a liquid discharge system.
In the chamber, a driving system is provided for moving a
steam-spraying nozzle relatively to a substrate surface to be
processed, so as to sweep the substrate surface. A point nozzle or
a line slit nozzle is disposed in the chamber.
[0143] FIG. 4 shows a one-by-one resist-peeling apparatus including
a spinning mechanism. This apparatus comprises a steam process
chamber 23 provided with a spinning mechanism 22 for rotating a
substrate 21, and a lamp chamber 26 including an ultraviolet lamp
24 and having a quartz window board 25. A gas inlet 27 to the
chamber and a discharge duct 28 are accompanied.
[0144] When steam is introduced into the process chamber from the
steam supply apparatus (see FIG. 3), the steam introduction valve
12 is opened. When steam is sprayed onto a surface to be processed,
the steam-spraying valve 13 is opened and steam is sprayed onto the
surface of the substrate 21 through the steam-spraying nozzle
14.
[0145] Shown is an example of the steam-spraying nozzle 14 in which
a line slit nozzle is disposed in a radial direction.
[0146] Alternatively, usable is a system including a spot nozzle
driven radially, or several nozzles movable in a proper distance or
fixed. The spraying angle and spraying distance of the nozzle and
the linear velocity of sprayed steam are optimized in various
respects, such as the object of the process, the surface structure
of the substrate, and protection for damage.
[0147] The steam process chamber 23 is kept in temperature. Steam
is condensed little by little on the inner wall of the chamber. It
serves for cleaning the inner wall. In this manner, the interior of
the chamber is always kept clean.
[0148] The gas inlet 27 to the chamber is used for changing the
atmosphere when a substrate is taken in/out. It is used also for
adding an ingredient effective for the process, to the atmosphere.
The discharge duct 28 preferably has a cooling structure.
[0149] (2) Physical Peeling Promotion:
[0150] Quenching (Rapidly Cooling) Resist Film:
[0151] Although not shown in FIG. 4, a carbonic acid gas-spraying
nozzle can be disposed to be opposite to a substrate surface. It is
for spraying carbonic acid gas and the resultant dry ice particles
onto the substrate surface to quench (cool rapidly) the resist
film. The resist film which was heated and swelled,
shrinks/solidifies and is peeled off the substrate. It has been
confirmed that such a quenching process promotes the peeling-off
operation of some kinds of resists.
[0152] High-Speed Spinning:
[0153] When the number of revolution of the substrate is set at
2000 rpm or more using the spinning mechanism, the peeling-off
operation is promoted. In particular, the peeling-off operation is
promoted when the steam-spraying effect is weak on the peripheral
portion.
[0154] 6. Making Resist-Peeling Process and Surface-Cleaning
Process after Peeling Off, Sequential
[0155] A resist-peeling process and a surface-cleaning process
after resist-peeling can be a sequential process.
[0156] Switching from the resist-peeling apparatus to a
surface-cleaning apparatus after resist-peeling is simple.
[0157] By altering the aqueous solution line 11 of the steam supply
apparatus of FIG. 3 into a switching system between a
peeling-promotion solution line 11A and a surface-cleaning solution
line 11B, the resist-peeling apparatus and a surface-cleaning
apparatus after resist-peeling can be switched freely.
[0158] Since the combination of the steam and ultraviolet processes
effectively shortens both the peeling time and the cleaning time,
the unity of the processes can be realized with no decrease in
throughput.
EXAMPLES
[0159] Hereinafter, specific examples of the present invention will
be described. Although the description is omitted in each example,
the resist-peeling state is obtained by observing the peeled
surface at each spraying time with an optical microscope.
Example 1
[0160] Shown are examples of peeling resist films by steam of pure
water.
[0161] Sample: FIG. 5A; a resist film formed on a dry-etched
thermal oxidation film;
[0162] FIG. 5B; a resist film formed on a dry-etched gate electrode
(polysilicon film)
[0163] Steam: steam of pure water
[0164] Result of Peeling:
[0165] As shown in the below Table 6, peeling could be performed by
spraying for thirty seconds to one minute.
6TABLE 6 Steam Effect and Peeling Result pure-water spraying time
steam 15 sec 30 sec 1 min oxide film dry- 100.degree. C. partially
fully peeled etched surface saturated remained steam gate electrode
100.degree. C. -- partially fully peeled etched surface saturated
remained steam steam quantity: 2.55 L/sec; point nozzle: inside
diameter of 10 mm, 32 m/sec
Example 2
[0166] Shown are examples of peeling resist films by steam
containing promotion ingredients.
[0167] The resist films have been ion-implanted and are known to be
very hard to peel off.
[0168] Sample: FIG. 5C; silicon thermal oxidation film dry-etched;
its underlayer of a silicon substrate ion-implanted;
[0169] Ion-implantation conditions: acceleration energy of 80 keV;
dose amount of phosphorus of 6.times.10.sup.15/cm.sup.2;
[0170] Promotion ingredient-containing steam: promotion ingredient;
alkali (KOH) and a surface active agent.
[0171] Result of Peeling:
[0172] As shown in Table 7, peeling could be performed by spraying
steam for two minutes. In case of the promotion ingredient of
alkali, some peeled-off pieces adhering to the surface after
peeling were observed. But, in case of the promotion ingredient of
alkali+surface active agent, no peeled-off piece is found.
7TABLE 7 Effect of Quality-change Promotion Ingredient and Peeling
Result quality- change promotion spraying time ingredient 1 min 2
min oxide film alkali partially fully peeled etched/ion-implanted
remained (peeled-off pieces surface adhered) oxide film alkali +
partially fully peeled etched/ion-implanted surface remained (no
peeled-off piece surface active agent adhered)
Example 3
[0173] Shown are further examples of peeling resist films by steam
containing promotion ingredients.
[0174] Sample: FIG. 5D; silicon thermal oxidation film wet-etched;
a negative-type resist film;
[0175] FIG. 5E; after etching metal wiring; a positive-type resist
film;
[0176] Promotion ingredient-containing steam: promotion ingredient;
hydrogen peroxide and a surface active agent.
[0177] Result of Peeling:
[0178] The resist film was fully peeled off the surface of the
thermal oxidation film by spraying steam containing the promotion
ingredient for one minute. The resist film was fully peeled even
off the etched metal wiring/ion-implanted surface inferior in
ability of peeling, in two minutes.
8TABLE 8 Effect of Quality-change Promotion Ingredient and Peeling
Result quality- change promotion spraying time ingredient 30 sec 1
min 2 min oxide film wet- hydrogen partially fully peeled etched
surface peroxide remained metal wiring hydrogen partially fully
peeled etched/ion-implanted peroxide remained surface
Example 4
[0179] Shown are examples by two-step steam processes for
metal-wiring surfaces.
[0180] Object of two-step process: it aims at avoiding chemical
damage to metal wiring. A promotion ingredient is used when the
metal-wiring surface is covered with a resist film. No promotion
ingredient is used after the resist film is peeled off the
metal-wiring surface to be exposed.
[0181] Details of two-step process:
[0182] first step (steam-contacting process); using steam
containing alkali;
[0183] second step (steam-spraying process); using steam of pure
water.
[0184] Result of Peeling:
[0185] Table 9 shows the results. The resist film was removed by
the steam process of the second step for thirty seconds, and the
metal wiring was not damaged.
[0186] For comparison, an example of process only with steam
containing alkali is shown. This case required two minutes of
spraying time, and some damages to the metal wiring on the surface
after removing the resist film were observed.
9TABLE 9 Effect of Two-step Steam Processing for Device first step
second step resist removal steam- steam- state processing
contacting spraying [state of metal step process process wiring]
condition kind of steam saturated saturated removed in removal
steam steam no process time promotion containing promotion of 1 min
and ingredient alkali ingredient 30 sec temperature 100.degree. C.
100.degree. C. [no damage to of steam metal wiring] processing 1
min 30 sec time comparison kind of steam no first saturated removed
in removal step steam spraying time promotion contain- of 2 min
ingredient ing alkali temperature 100.degree. C. [damages to of
steam metal wiring] processing 2 min time
Example 5
[0187] Shown are examples by hot steam processes for ion-implanted
resist films, which are hard to peel off.
[0188] Sample: FIG. 5C; silicon thermal oxidation film etched; its
underlayer of a silicon substrate ion-implanted;
[0189] Ion-implantation conditions: acceleration energy of 80 keV;
dose amount of phosphorus of 6.times.10.sup.13/cm.sup.2
[0190] Result of Peeling:
[0191] Table 10 shows the results.
[0192] In the 100.degree. C. saturated steam process of the
condition 1, the resist film could not be removed even by spraying
for ten minutes.
[0193] In the 120.degree. C. saturated steam process of the
condition 2, the resist film could be removed by contacting process
for two minutes and spraying process for one minute.
[0194] In the 140.degree. C. superheated steam process after the
130.degree. C. saturated steam process for thirty seconds of the
condition 3, the resist film could be removed by spraying process
for thirty seconds.
[0195] A quality-change effect by hot saturated steam and a peeling
effect by superheated steam at a high temperature were
confirmed.
10TABLE 10 Effect of High-temperature Superheated Steam for Ion-
implanted Resist Removal first step second step steam- steam-
processing contacting spraying resist removal step process process
result condition 1 kind of no first step saturated could not be
steam steam removed by temperature 100.degree. C. spraying for of
steam 10 min processing 10 min time condition 2 kind of saturated
saturated removed in steam steam steam processing temperature
120.degree. C. 120.degree. C. time of 3 min of steam processing 2
min 1 min time condition 3 kind of saturated superheated removed in
steam steam steam processing temperature 130.degree. C. 140.degree.
C. time of 1 min of steam processing 30 sec 30 sec time
Example 6
[0196] Shown are examples by combinations of steam and ultraviolet
processes for ion-implanted resist films, which are hard to peel
off.
[0197] Ultraviolet lamp: KrI excimer lamp, wavelength; 191 nm;
[0198] Ultraviolet irradiation quantity: 10 mW/cm.sup.2 (surface to
be processed).
[0199] Result of Peeling:
[0200] Table 11 shows the results.
[0201] After the 100.degree. C. saturated steam process and the
ultraviolet irradiation process for two minutes of the condition 1,
the resist film could be removed by spraying process for one
minute.
[0202] After the 120.degree. C. saturated steam process and the
ultraviolet irradiation process for thirty seconds of the condition
2, the resist film could be removed by spraying process for thirty
seconds.
11TABLE 11 Effect of Ultraviolet Irradiation Superimposition for
Ion-implanted Resist Removal first step steam- contacting process
ultraviolet second step irradiation steam- processing super-
spraying resist removal step imposition process state condition 1
kind of saturated saturated removed in steam steam steam processing
temperature 100.degree. C. 100.degree. C. time of 3 min of steam
processing 2 min 1 min time condition 2 kind of saturated
superheated removed in steam steam steam processing temperature
120.degree. C. 130.degree. C. time of 1 min of steam processing 30
sec 30 sec time
Example 7
[0203] Shown are examples by a sequential process of resist-peeling
and surface-cleaning after peeling.
[0204] Ultraviolet lamp: KrI excimer lamp, wavelength; 191 nm;
[0205] Ultraviolet irradiation quantity: 10 mW/cm.sup.2 (surface to
be processed).
[0206] Resist-Peeling Step:
[0207] Saturated steam at temperatures to meet various resist
processes was used. Resist-peeling is performed by the first step
of steam-contacting and the second step of steam-spraying with
combining ultraviolet irradiation.
[0208] Cleaning Step:
[0209] Steams containing chemicals are generated by supplying the
chemicals one after another through a cleaning liquid supply line.
First, saturated steam containing fluoric acid and hydrogen
peroxide is sprayed onto a substrate surface to remove metal and
organic matters. At this time, particles are removed by the
spraying power of a steam mist. Next, saturated steam containing
diluted fluoric acid is sprayed onto the substrate surface. For
example, the silicon surface of a contact hole in the substrate
becomes bare silicon. Finally, steam of pure water is sprayed to
wash. Such a chemical prescription is selected in accordance with
the object of the process.
[0210] Drying Step:
[0211] Because superheated steam contains no mist, rapidly drying
can be performed. Ultraviolet irradiation combined performs
completion of surface-cleaning as well as a promotion of
drying.
[0212] Result of Peeling:
[0213] Both the resist removal and the surface-cleaning were
completely performed.
12TABLE 12 Making Resist-peeling Process and Surface-cleaning
Process after Peeling Sequential first/second step cleaning step
drying step steam steam steam processing processing processing
ultraviolet ultraviolet ultraviolet irradiation irradiation
irradiation super- super- super- processing step imposition
imposition imposition kind of saturated steam steam temperature 100
to 140.degree. C. of steam processing according to time each resist
kind of saturated steam steam temperature 100 to 140.degree. C. of
steam kind of fluoric acid/ dil. pure cleaning hydrogen fluoric
water liquid peroxide acid cleaning 15 sec 15 sec 10 sec time kind
of superheated steam steam temperature 120 to 140.degree. C. of
steam drying time 10 sec nitrogen 10 sec introduction time
[0214] --Various Embodiments According to Other Aspects of the
Present Invention--
[0215] As described above, the present inventors have realized
techniques of peeling resist films with steam, besides, they have
established techniques for combining them with promotion effects by
chemical ingredients and effects by ultraviolet irradiation.
[0216] Additionally, the present inventors now propose techniques
to make the peeling-off operation more sure and rapid by closely
cross-combining applications of peeling actions, i.e., operations
of peeling mechanisms, in relation to timely and spatial
conditions, temperature conditions, and physicochemical conditions.
That is, the present inventors grasp the peeling techniques from a
new viewpoint that the properly cross-combining manners of the
above conditions are considered, and make it possible to realize
the techniques for this purpose and grasp them practically.
[0217] 1. Cross-Combination of Process conditions
[0218] In general, process conditions are mostly set in a
stationary state. However, peeling a film is a phenomenon of a
break of a stationary state, i.e., an adhering state. Therefore,
peeling is a non-stationary phenomenon essentially. For example, a
resist film is hydrated and swelled by an effect of steam, but it
is never peeled off only by keeping the physicochemical state. A
physical action, i.e., spraying, is required for peeling the film.
Thus the peeling process requires a non-stationary
cross-combination of various conditions.
[0219] Proper cross-combination is not a mere combination of
different conditions. Proper cross-combination is an arrangement of
conditions on the premise of an estimate and grasp of means and
results. In detail, it includes interception condition design,
inversion condition design, variation condition design, etc. A
proper cross-combination of such process conditions produces an
effect.
[0220] In particular, the following is the most principal reason
why peeling techniques for resist films require such a proper
cross-combination of process conditions. There is an untouchable
ground that protection of the minute structure of the exposed
surface after peeling must be ensured. In a peeling process, the
surface of the resist film and the surface of the minute structure
coexist temporarily. Conditions effective for peeling may cause
damages on the minute structure surface. For reconciling peeling
and protection of the minute structure surface, a proper
cross-combination of process conditions is necessary.
[0221] 2. Specific Modes of Proper Cross-Combinations of Process
conditions
[0222] (1) Modes of Timely and Spatially Proper
Cross-Combinations
[0223] In modes of timely cross-combinations, for example, the
order of operations of two conditions or mechanisms A and B is set
at A.fwdarw.B, A.rarw.B, or A and B at once, and an operation time
is set to either of A and B.
[0224] Modes of spatially proper cross-combinations include, e.g.,
cases of processing the whole surfaces, one surface, and a partial
surface.
[0225] (2) Modes of Proper Cross-Combinations on Temperature
[0226] The portions to be heated and/or cooled are selected to the
whole surfaces, one surface, or a partial surface to be processed.
For example, a combination of one surface heating and one surface
cooling is made. Preheating or rapid heating, or pre-cooling or
rapid cooling is selected. Also possible are modes in which
cross-combinations on temperature are further cross-combined timely
or spatially.
[0227] (3) Modes of physicochemically Proper Cross-Combinations
[0228] These modes include combinations on composition and
combinations on concentration of chemical ingredients, and timely
and spatially proper cross-combinations of applications of chemical
ingredients. Irradiation with high frequency supersonic waves or
ultraviolet rays may be combined.
[0229] The above modes (1), (2), and (3) can be properly
cross-combined with one another.
[0230] 3. Specific Examples of Proper Cross-Combinations of Process
conditions
[0231] Specific examples of proper cross-combinations will be
described below, though the present invention is not limited to
those examples.
[0232] (1) Cross-Combination of Steam-Contact and Steam-Spraying
(Timely Cross-Combination)
[0233] A certain time is required for a resist film to be swelled
and hydrated by a chemical action. For this process, suitable is a
process of stationary contact with steam. After the resist film has
changed in its quality due to the steam, spraying power of steam is
required. That is, a steam-contact process and a steam-spraying
process should be combined at a time interval.
[0234] A specific example of this mode is the above example 4,
which is a proper cross-combination of a steam-contact process, a
steam-spraying process, and alkali.
[0235] (2) Cross-Combination of Saturated Steam Process and
Superheated Steam Process (Timely and Physicochemically Proper
Cross-Combination and Proper Cross-Combination on Temperature)
[0236] Saturated steam gives wetting conditions, and superheated
steam gives hot drying conditions. For example, a 100.degree. C.
saturated steam process and a 100.degree. C. saturated-150.degree.
C. superheated steam process are properly cross-combined. In the
100.degree. C. saturated steam process, swelling and hydration of a
resist film progress. In the 100.degree. C. saturated-150.degree.
C. superheated steam process, the adhesion boundary of the resist
film is dried, and this causes peeling at the boundary. Thus
effective is a combination of the 100.degree. C. saturated steam
process and the 100.degree. C. saturated-150.degree. C. superheated
steam process at a proper time interval.
[0237] Besides, a superheated steam process can be effectively used
for drying after peeling and washing.
[0238] A specific example of this mode is the above example 5,
which is a proper cross-combination of saturated and superheated
steams.
[0239] (3) Cross-Combination of Steam Process and Chemical
Ingredient-Containing Steam Process (Physicochemically and Timely
Proper Cross-Combination)
[0240] It has been confirmed that a change in quality of a resist
film is accelerated by steam containing a chemical ingredient. For
example, steam containing an alkali ingredient can rapidly peel a
resist film. However, if the underlayer is a minute structure of,
e.g., a metal wiring surface, the wiring material such as aluminum
or copper (in particular, aluminum) is etched and damaged by
alkali. In this case, by using steam containing a certain kind of
surface active agent, chemical damage on aluminum can be reduced to
the extent that is usually negligible.
[0241] Specific examples of this mode are the above examples 2 and
3, which are proper cross-combinations of alkali and hydrogen
peroxide.
[0242] (4) Cross-Combination of Steam Process and Isopropyl Alcohol
(IPA) Vapor Process
[0243] A resist-peeling effect of an IPA-water-salt base peeling
liquid is known. Gas-liquid interface action of IPA is well-known
as Marangoni effect. The present inventors have found that IPA
vapor shows an resist-peeling promotion effect in an atmosphere of
steam. Since IPA is an organic chemical ingredient which never acts
on a surface material, it can be used without any damage on a metal
wiring surface.
[0244] Cross-Combination Mode 1: (Timely and Physicochemically
Proper Cross-Combination)
[0245] A steam process and an IPA vapor process are timely
cross-combined.
[0246] Cross-Combination Mode 2: (Physicochemically Proper
Cross-Combination)
[0247] An IPA vapor process, i.e., a composition of chemical
ingredient is cross-combined.
Example 8
[0248] Effects of cross-combinations of IPA vapor processes in
steam processes were examined in relation to various kinds of
resist films.
[0249] By cross-combined process conditions shown in the below
table 13, resist-peeling could be performed in one to two
minutes.
13TABLE 13 Cross-Combination with IPA Vapor Process time resist
combined processes distribution removal time cross- first step:
steam process 0.4 1-2 min combination second step: IPA vapor 0.2
mode 1 process third step: steam process 0.4 cross- IPA-containing
steam process -- 1-2 min combination mode 2 time distribution:
ratio of each process time to the whole process time IPA-containing
steam: IPA/steam = 0.1/1.0 (volume ratio) steam: 120.degree. C.
saturated steam, 2.5-5 L/sec (substrate spinning)
[0250] (5) Cross-Combination of Steam Process and Water-spraying
Process and Application of High-frequency Supersonic Waves
[0251] There are resist films which can fully be peeled off by the
spraying power of steam after a steam process, and resist films
which require certain times for being peeled off only by the
spraying power of steam. In the latter case, a cross-combination of
a water-spraying process is effective. When the sprayed quantities
are the same, the collision power of water is greater than that of
steam in proportion to the difference in mass by about three
figures. Besides, the resist which has been softened at the
temperature of steam, is cooled by sprayed water to be hardened.
This serves as an additional peeling action.
[0252] Highly compressed water, i.e., a jet water stream is used
for cutting a silicon wafer or as a surgical knife. Spraying
compressed water can peel any stable film, but protection of the
surface to be minutely processed, from being damaged, must be fully
ensured. Therefore, important is design of the linear velocity of
sprayed water, for relieving pressure and sprayed quantity, i.e.,
for protection of minute structure.
[0253] Cross-Combination Mode 1: (Timely and Physicochemically
Proper Cross-Combination)
[0254] A water-spraying process at a relieved pressure is performed
after a steam-contact process. Obtained is a united effect of a
pyrogenetic chemical reaction of steam and a cooling action of
compressed water.
[0255] Cross-Combination Mode 2: (Spatially Proper
Cross-Combination and Proper Cross-Combination on Temperature)
[0256] In spinning a surface, a steam-spraying process is performed
on one side, and a water-spraying process is performed on the other
side. Vibration of temperature is thereby applied to the surface in
a cycle of heating and cooling in accordance with the spinning
speed. Also in this cross-combination mode, the same peeling effect
as the above can be obtained.
[0257] Cross-Combination Mode 3: (Physicochemically Proper
Cross-Combination)
[0258] In one of the above cross-combination modes 1 and 2, the
water-spraying process is performed using a high-frequency
supersonic nozzle. Because the spraying energy and the supersonic
energy are summed to increase the peeling power, the process is
performed under conditions by which each energy is relieved in
order to ensure the protection of the target minute circuit
structure.
Example 9
[0259] Effects of cross-combinations of steam processes and
water-spraying processes and applications of high-frequency
supersonic waves were examined in relation to various kinds of
resist films. By cross-combined process conditions shown in the
below table 14, resist-peeling could be performed in one to two
minutes.
14TABLE 14 Cross-Combination with Water spraying Process and High-
frequency Supersonic Process time resist combined process
distribution removal time cross- first step: steam contact 0.5 1-2
min combination second step: water spraying 0.5 mode 1 cross- one
surface steam spraying simultaneous 1-2 min combination one surface
water spraying simultaneous mode 2 cross- one surface steam
spraying simultaneous 1-2 min combination one surface water
spraying simultaneous mode 3 with applying high-frequency
supersonic steam: 120.degree. C. saturated steam, 2.5-5 L/sec
(substrate spinning)
[0260] (6) Cross-Combination of Steam Process and Compressed
Carbonic Acid Gas-spraying Process
[0261] This cross-combination produces a special effect in addition
to the effect of cooling and hardening in the cross-combination of
the above water-spraying process.
[0262] The temperature of fine dry ice particles generated by
spraying compressed carbonic acid gas, is -55.degree. C. Moisture
which has permeated into the adhesion boundary in the steam
process, momentarily crystallizes and expands by spraying carbonic
acid gas. This freezing of the moisture brings about an effect of
ice columns, and serves as a strong additional peeling power.
[0263] Cross-Combination Mode 1: (Timely and Physicochemically
Proper Cross-Combination and Proper Cross-Combination on
Temperature)
[0264] By alternately repeating a steam process and a compressed
carbonic acid gas-spraying process, obtained is a peeling effect by
temperature vibration of heating and cooling. This is because the
coefficient of expansion varies in accordance with the kind of
material. For example, the linear expansion coefficient of silicon
is 0.076.times.10.sup.-4/K, while those of many organic materials
are 2.2 to 5.0.times.10.sup.-4/K. There is a difference by about
one to two figures. The difference in linear expansion coefficient
between a silicon substrate and a resist film brings about a
peeling power at the boundary by the temperature amplitude of about
150.degree. C.
[0265] Cross-Combination Mode 2: (Spatially and Physicochemically
Proper Cross-Combination and Proper Cross-Combination on
Temperature)
[0266] In spinning a surface, a steam-spraying process is performed
on one side, and a compressed carbonic acid gas-spraying process is
performed on the other side. Vibration of temperature is thereby
applied to the surface in a cycle of heating and cooling in
accordance with the spinning speed. Also in this cross-combination
mode, the same peeling effect as the above can be obtained.
[0267] Cross-Combination Mode 3: (Spatially and Physicochemically
Proper Cross-Combination and Proper Cross-Combination on
Temperature)
[0268] A steam-spraying process is performed onto the resist-side
surface of a substrate, and a compressed carbonic acid gas-spraying
process is performed onto the opposite surface of the substrate. A
difference in temperature is thereby made between the resist film
and the substrate at their boundary. Also in this cross-combination
mode, the same peeling effect as the above can be obtained.
Example 10
[0269] Effects of cross-combinations of steam processes and
compressed carbonic acid gas-spraying processes were examined in
relation to various kinds of resist films. By cross-combined
process conditions shown in the below table 15, resist-peeling
could be performed in one to two minutes.
15TABLE 15 Cross-Combination with Compressed Carbonic Acid Gas
spraying Process time resist combined process distribution removal
time cross- steam spraying 5 sec/process alternate 1-2 min
combination CO.sub.2 gas spraying 5 sec/ alternate mode 1 process
cross- one surface steam spraying simultaneous 1-2 min combination
one surface CO.sub.2 gas spraying simultaneous mode 2 cross- front
surface steam spraying simultaneous 1-2 min combination back
surface CO.sub.2 gas spraying simultaneous mode 3 steam:
120.degree. C. saturated steam, 2.5-5 L/sec (substrate
spinning)
[0270] (7) Cross-Combination of Steam Process and Substrate Cooling
Process (Proper Cross-Combination on Temperature)
[0271] The resist-side surface of a substrate is processed by steam
with supporting the substrate on a cooling plate. The cooling plate
may perform cooling by any of an electronic cooling method using a
Peltier element, a fluoric oil coolant circulation method, and a
ventilation cooling method by spraying compressed carbonic acid
gas.
[0272] Obtained are the same united effect and peeling action as
those by cooling by the above water- or compressed carbonic acid
gas-spraying process.
Example 11
[0273] Effects of cooling substrates in steam processes were
examined in relation to various kinds of resist films. The
cross-combination order of a steam-spraying process and a substrate
cooling process and the process time of each of them vary in
accordance with the kind of resist, so conditions to obtain greater
effects are selected. The below table 16 shows examples of such
conditions. By the conditions shown, resist-peeling could be
performed in one-to two minutes.
16TABLE 16 Cross-Combination with Substrate Cooling Process time
resist combined process distribution removal time cross- substrate
cooling step 0.5 1-2 min combination steam spraying step 0.5 mode 1
cross- front surface steam spraying 0.5 1-2 min combination
(120.degree. C. saturated) mode 2 back surface cooling 0.5 steam:
120.degree. C. saturated steam, 2.5-5 L/sec (substrate spinning)
substrate cooling: Peltier element electronic cooling method,
substrate temperature: -10.degree. C.
[0274] (8) Cross-Combination of Steam Process and Ultraviolet
Irradiation Process (Physicochemically Proper
Cross-Combination)
[0275] In case of combination with a steam process, used are
ultraviolet rays whose 50% transmissive distance to steam is 2 mm
or more. A combination with a superheated steam process is
effective. Since superheated steam contains no mist, scattering
loss of ultraviolet rays is little. A light quantity and an
irradiation time of ultraviolet rays suffice if they bring about a
change in quality of the adhering surface of a resist film by a
photochemical action.
[0276] A specific example of this mode is the above example 6,
which is a proper cross-combination of steam and ultraviolet
rays.
[0277] (9) Cross-Combination of High-pressure Carbonic Acid Gas
Process and Ultraviolet Irradiation Process (Physicochemically
Proper Cross-Combination)
[0278] In an atmosphere of carbonic acid gas, even short-wavelength
ultraviolet rays whose 50% transmissive distance to steam is less
than 2 mm, can be used with a high transmissivity. The transmissive
distance of ultraviolet rays of the wavelength of 172 nm is about
30 cm. That is, a Xe excimer lamp (wavelength: 172 nm) can be used.
This is effective to decompose and remove fine resist pieces which
have remained within fine gaps of the structure after peeling a
resist film.
Example 12
[0279] In case of processes of peeling resist films off device
surfaces having minute structural patterns, after which processes
fine resist pieces remain at the corners of the patterns and within
gaps of wiring patterns, decomposing and removing processes for the
remaining resist pieces were performed by ultraviolet irradiation
processes.
[0280] Surfaces to be processed were irradiated by a Xe excimer
lamp with spraying carbonic acid gas onto the surfaces. The below
table 17 shows the results.
17TABLE 17 Ultraviolet Irradiation Process for Remaining Resist
Pieces resist remaining ultraviolet surface SEM inspection after
process state irradiation time remaining resist remaining a little
10-20 sec could not detect in minute pattern gaps. resist residues
about 1 min could not detect scattered Xe excimer lamp: irradiation
quantity 20 mW/cm.sup.2 (substrate spinning)
[0281] (10) Cross-Combination with Cleaning Process
[0282] The purification level of the surface which a resist film
has been peeled off, or the purification level of the surface
required in the subsequent process varies in accordance with the
process in question. Therefore required is a system in which proper
cross-combinations of steam conditions and a cross-combination of
ultraviolet irradiation can easily be set.
[0283] A specific example of this mode is the above example 6,
which is a cross-combination with a cleaning process.
[0284] 4. Resist Film Removing Apparatus
[0285] A specific example of resist film removing apparatus wherein
cross-combination modes of various processes (means) are taken into
consideration, will be described.
[0286] FIG. 6 is a schematic sectional view of a one-by-one resist
film removing apparatus including a spinning mechanism.
[0287] This resist film removing apparatus is provided with a
chamber having a substrate taking-in/out system, an atmosphere
purge system, and a discharge system. In the chamber, in addition
to a system for introducing steam, provided is at least one of
systems for respectively introducing IPA vapor, water, and
compressed carbonic acid gas; a system for adding a chemical
ingredient to the above steam or water; systems for respectively
performing irradiation with ultraviolet rays and high-frequency
supersonic waves; and a system for heating and cooling substrates.
A driving system is provided for moving each spraying nozzle
relatively to the front or back surface of a substrate-so as to
sweep the surface.
[0288] A spinning mechanism is provided in the steam process
chamber 101. The spinning mechanism comprises a rotor 104 provided
with support pins 103 for fixing a substrate 102, and a hollow
cylindrical motor 105.
[0289] As a substrate cooling system, a cooling plate 106 is
supported by a supporting mechanism fixed in the motor 105.
[0290] As an ultraviolet irradiation system, a lamp chamber 110
including an ultraviolet lamp 108 and having a quartz window board
109 is disposed on the upper part of the steam process chamber 101.
FIG. 6 shows a cross section of the ultraviolet lamp 108.
[0291] As systems for respectively introducing steam, water, IPA
vapor, and compressed carbonic acid gas, the steam process chamber
101 is provided with a steam inlet 111 and a steam spraying nozzle
112, a water spraying nozzle 113, an IPA vapor spraying nozzle 114,
and a compressed carbonic acid gas spraying nozzle 115. A rear side
nozzle 116 for compressed carbonic acid gas is used for cooling the
substrate 102 in place of the cooling plate 106.
[0292] As a high-frequency supersonic irradiation system, the water
spraying nozzle 113 is provided with a high-frequency supersonic
oscillator 117. The shape of each spraying nozzle is schematically
shown in FIG. 6.
[0293] The steam process chamber 101 is further provided with an
atmosphere purge gas inlet 118 and a discharge system 119.
[0294] As a system for adding a chemical ingredient to steam or
water, a chemical injecting device 122 comprising a fixed flow rate
pump is connected to an ultrapure water supply line 121 for a steam
generator 120 and the and the water spraying nozzle 113.
* * * * *