U.S. patent application number 09/840111 was filed with the patent office on 2001-08-16 for substrate processing method and apparatus.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Ito, Shinichi, Nakamura, Hiroko, Okumura, Katsuya.
Application Number | 20010014536 09/840111 |
Document ID | / |
Family ID | 13057511 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014536 |
Kind Code |
A1 |
Nakamura, Hiroko ; et
al. |
August 16, 2001 |
Substrate processing method and apparatus
Abstract
Disclosed herein is a method for processing a substrate. The
method includes supplying a liquid agent such as a developer onto
the surface of a substrate, bringing an upper surface of a film
formed of the liquid agent into contact with a liquid agent holding
member arranged so as to face the substrate, holding the liquid
agent between the substrate and the liquid agent holding member,
moving the substrate or the liquid agent holding member, or both,
in parallel to the main surface of the substrate, while the main
surface of the substrate is being treated with the liquid agent.
Since the concentrations of reaction products and starting reaction
materials become uniform in the liquid agent which contacts the
substrate, the entire substrate can be processed uniformly.
Inventors: |
Nakamura, Hiroko;
(Yokohama-shi, JP) ; Ito, Shinichi; (Yokohama-shi,
JP) ; Okumura, Katsuya; (Yokohama-shi, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
13057511 |
Appl. No.: |
09/840111 |
Filed: |
April 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09840111 |
Apr 24, 2001 |
|
|
|
09255659 |
Feb 23, 1999 |
|
|
|
Current U.S.
Class: |
438/689 ;
156/345.11 |
Current CPC
Class: |
G03F 7/3021 20130101;
H01L 21/6715 20130101 |
Class at
Publication: |
438/689 ;
156/345 |
International
Class: |
H01L 021/302; C23F
001/02; H01L 021/461 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 1998 |
JP |
10-057502 |
Claims
1. A substrate processing method comprising: a first step of
supplying a liquid agent onto a main surface of a substrate; a
second step of holding the liquid agent between the substrate and a
liquid agent holding member by bringing an upper surface of a film
of the liquid agent in contact with the liquid agent holding member
which faces the substrate; and a third step of moving at least one
element of the substrate and the liquid agent holding member in
parallel to the main surface of the substrate, after the second
step, in order to treat uniformly the main surface of the substrate
with the liquid agent.
2. The substrate processing method according to claim 1, wherein
the second step includes a step of using a liquid agent supply
nozzle as the liquid agent holding member.
3. The substrate processing method according to claim 1, wherein
the first step includes a step of applying the liquid agent, by use
of a disc nozzle with plural liquid agent outlet holes or by use of
a linear nozzle which has a linear developer supply section whose
length is almost the same as a diameter of the wafer, while
rotating the substrate or moving the linear nozzle from one end of
the substrate to the other in parallel to the main surface of the
substrate which is at a sandstill.
4. The substrate processing method according to claim 1, wherein
the second step includes a step of moving the liquid agent holding
member so as to face the substrate and bringing the liquid agent
holding member in contact with an upper surface of the film of the
liquid agent.
5. The substrate processing method according to claim 1, wherein
the third step includes a step of performing reciprocating movement
or rotational movement.
6. The substrate processing method according to claim 5, wherein
the rotational movement includes rotating the substrate while the
liquid agent holding member is immobilized.
7. The substrate processing method according to claim 1, wherein
the velocity of the rotational movement is 10 to 50 rpm.
8. The substrate processing method according to claim 1, wherein
the first step includes a step of forming a single liquid-agent
film on a surface of the liquid agent supply nozzle facing the
substrate, supplying the liquid agent to the main surface of the
substrate in the form of film, and using the liquid agent supply
nozzle as the liquid agent holding member.
9. The substrate processing method according to claim 8, wherein
the first step includes a step of supplying the liquid agent to an
entire surface of the substrate almost simultaneously.
10. The substrate processing method according to claim 8, wherein
the first step includes a step of supplying the liquid agent onto
the main surface of the substrate while a substrate surface facing
the liquid agent supply nozzle remains in a convex form.
11. The substrate processing method according to claim 3, wherein
the first step includes a step of supplying the liquid agent by
using the liquid agent supply nozzle having the surface made in a
convex form.
12. The substrate processing method according to claim 1, wherein
the first step includes a step of supplying the liquid agent while
reducing pressure in a space provided between the substrate and the
liquid agent supply nozzle.
13. The substrate processing method according to claim 1, wherein
the liquid agent is one selected from the group consisting of a
developer, an etching solution, a washing solution, a remover
agent, a film formation solution and a plating liquid.
14. The substrate processing method according to claim 1, further
comprising a step of rinsing the liquid agent holding member
simultaneously with the main surface of the substrate by replacing
the liquid agent with a rinse solution after the third step.
15. A substrate processing apparatus comprising: a table on which a
substrate is to be mounted; a liquid agent supply nozzle for
supplying a liquid agent onto a main surface of the substrate; a
liquid agent holding member facing the substrate and movable up and
down in order to be in contact with an upper surface of the
film-form liquid agent; and a mechanism for moving at least one
element of the substrate and the liquid agent holding member in
parallel to the main surface of the substrate while the liquid
agent holding member is in contact with the upper surface of the
film-form liquid agent.
16. The substrate processing apparatus according to claim 15,
wherein the liquid agent supply nozzle serves also as the liquid
agent holding member.
17. The substrate processing apparatus according to claim 15,
wherein the mechanism includes a reciprocating drive mechanism or a
rotational drive mechanism.
18. The substrate processing apparatus according to claim 15,
wherein the liquid agent supply nozzle has a plurality of liquid
agent outlet holes in a surface facing the substrate, any two of
the liquid agent outlet holes adjacent to each other in a moving
direction of the substrate passing through different regions of the
substrate when the nozzle moves relative to the substrate.
19. The substrate processing apparatus according to claim 15,
wherein the liquid agent supply nozzle has a plurality of liquid
agent outlet holes in a surface facing the substrate, the liquid
agent outlet holes being uniformly distributed in a plane facing
the substrate.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a substrate processing
method and apparatus for use in a semiconductor device, a liquid
crystal display and the like. More specifically, the present
invention relates to a method and apparatus for processing a
substrate by using a liquid agent.
[0002] In the semiconductor device and liquid crystal display,
desired functions can be imparted by applying various types of
processing to a substrate and forming a micro pattern on the
substrate. To process the substrate as mentioned above, not only a
dry process using a gas but also a wet process using a liquid agent
is widely employed. The wet processing is performed to develop a
photosensitive resist pattern, which will be used to form a micro
pattern.
[0003] To form a photosensitive resist pattern, a photosensitive
resist is applied on a film which has been formed on a silicon or
quartz substrate, thereby forming a photoresist film. An exposure
mask is placed above the photoresist film. Light is applied through
the mask, whereby a desired region of the resist film is exposed to
light. Subsequently, the light-exposed portion of the resist film,
if the resist film is a positive type one, or the non light-exposed
portion, if the resist film is a negative type one, is removed with
an organic solvent or an aqueous alkaline solution. As a result, a
photosensitive resist pattern is formed.
[0004] To form a chromium mask for use in light exposure, the wet
process is applied. After the chromium film is formed on a
substrate, a photosensitive resist pattern is formed. Those parts
of the chromium film which are not covered with the resist pattern
are isotropically removed by the wet-etching using a ceric nitrate
ammonium solution.
[0005] To remove unnecessary organic materials from a substrate
prior to processing, or to remove the photosensitive resin pattern
from a substrate after completion of etching, a mixed liquid agent
consisting of sulfuric acid and hydrogen peroxide is used.
[0006] If a silicon substrate is reacted with oxygen contained in
the air, a native oxide film will be formed. Since the native oxide
film prevents uniform processing, it must be removed. To remove the
native oxide film, a liquid agent such as NH.sub.4 or diluted HF is
applied.
[0007] In the case where a gold film is formed on a silicon
substrate, an Au plating solution is used.
[0008] Wet processing methods include a dip treatment in which the
substrate is dipped in a liquid agent, and a puddle treatment in
which the substrate is treated with a liquid agent supplied to the
main surface of the substrate. However, the dip treatment has
problems in that a large amount of the liquid agent is required and
in that the substrate may be contaminated with a material present
in the rear surface. Because of the problems, the paddle treatment
tends to be widely employed rather than the dip treatment. To
perform the puddle treatment, the substrate is fixed at the back by
a vacuum chuck (Jpn. Pat. Appln. KOKAI Publication No.
7-235473).
[0009] In the wet treatment, the treatment is performed through a
chemical reaction between a liquid agent and the film to be
treated. As the treatment proceeds, the concentration of reaction
products increases, whereas that of the starting liquid agent
decreases. Since the reaction products and the starting liquid
agents do not diffuse immediately, their concentrations varies
locally. Consequently, the surface of the film cannot always
processed uniformly.
[0010] In a developing method, for example, resist is removed from
a desired region of the substrate with an aqueous alkaline solution
and is dissolved by a neutralization reaction with the developer
(aqueous alkaline solution). This is because the resin forming a
resist removal region has an acidic group such as a carboxylic acid
or a phenol group as a side chain. The substrate is brought to a
standstill in a conventional development step, so that the
dissolved resin diffuses slowly. As a result, the dissolved resin
is left near the resist removal region. In addition, an OH group
does not diffuse sufficiently fast. The concentration of the OH
group is therefore locally low after the OH group is consumed in
the neutralization reaction. This reduces local pH. The volume of
the resin in the removal region, i.e., the amount of the resin to
be dissolved, depends on a pattern. Hence, the dimensions of the
photosensitive resist finally left on the substrate surface is not
uniform.
[0011] Then, the aforementioned publication No. 7-235473 discloses
the following method using a rotation-type resist developing
apparatus. In this apparatus, a capillary action is induced in the
treatment solution between the wafer and the liquid agent supply
board located in proximity of the wafer. The time required for
dispersing the treatment solution over the resist film can,
therefore, be reduced by the capillary action and thereby uneven
development decreases. However, in this method, development is
carried out at a predetermined time interval after the developer is
dispersed over the entire surface of the resist film. Thus, the
local change in pH of the developer inevitably occurs, as mentioned
above.
[0012] In the case where the developing process is performed while
stirring the developer, an ultrasonic oscillator is employed as
disclosed in a method of Jpn. Pat; Appln. KOKAI Publication No.
57-208134. However, when the ultrasonic oscillator is used, voids
are produced or destroyed in the liquid agent by the cavitation
effect due to the oscillation. Since the substrate has larger
acoustic impedance than the liquid agent, the void tends to form,
especially on the substrate. Due to voids, the liquid agent does
not always contact the substrate. As a consequence, the substrate
surface cannot be processed uniformly.
BRIEF SUMMARY OF THE INVENTION
[0013] The present invention relates to a substrate processing
method and apparatus for treating a substrate with a liquid agent.
The object of the present invention resides in that reaction
products and starting reaction materials are present in uniform
concentrations in the liquid agent in contact with a entire surface
of the substrate, and that the substrate can be processed uniformly
over its surface after it has been treated.
[0014] A main feature of the present invention resides in that a
substrate or a liquid agent holding member, or both are moved in
parallel to the main surface of the substrate during the treatment
with the liquid agent while the liquid agent remains in contact
with the liquid agent holding member. The liquid agent is thereby
stirred. The reaction products and the starting reaction materials
are therefore present in uniform concentrations in the liquid agent
which contacts the surface of the substrate. As a result, the
substrate can be processed, over its surface, with uniform accuracy
after it has been treated. In addition, since the liquid agent is
stirred, it is possible to prevent the reaction products from
accumulating near the substrate surface and to maintain the
concentration of the starting reaction materials. The processing
rate therefore can be improved.
[0015] To attain the aforementioned object, the substrate
processing method according to a first aspect of the present
invention comprises:
[0016] a first step of supplying a liquid agent onto a main surface
of a substrate;
[0017] a second step of holding the liquid agent between the
substrate and a liquid agent holding member by bringing an upper
surface of a film of the liquid agent in contact with the liquid
agent holding member which faces the substrate; and
[0018] a third step of moving at least one of the substrate and the
liquid agent holding member in parallel to the main surface of the
substrate, after the second step, in order to treat uniformly the
main surface of the substrate with the liquid agent.
[0019] The second step may include a step of using a liquid agent
supply nozzle as the liquid agent holding member.
[0020] The first step desirably includes a step of applying the
liquid agent, by use of a disc nozzle with plural liquid agent
outlet holes or by use of a linear nozzle which has a linear
developer supply section whose length is almost the same as a
diameter of the wafer while rotating the substrate or moving the
linear nozzle from one end of the substrate to the other in
parallel to the main surface of the substrate which is at a
sandstill.
[0021] It is desirable that the second step include a step of
moving the liquid agent holding member so as to face the substrate
and bringing the liquid agent holding member in contact with an
upper surface of the film of the liquid agent.
[0022] It is desirable that the third step include a step of
performing reciprocating movement or rotational movement.
[0023] It is desirable that the rotational movement include
rotating the substrate while the liquid agent holding member is
immobilized.
[0024] It is desirable that the velocity of the rotational movement
is 10 to 50 rpm.
[0025] It is desirable that the first step include a step of
forming a single liquid-agent film on a surface of the liquid agent
supply nozzle facing the substrate, supplying the liquid agent to
the main surface of the substrate in the form of film, and using
the liquid agent supply nozzle as the liquid agent holding
member.
[0026] The first step may include a step of supplying the liquid
agent to an entire surface of the substrate substantially at the
same time.
[0027] The first step may include a step of supplying the liquid
agent by using the liquid agent supply nozzle having the surface
made in a convex form.
[0028] The first step may include a step of supplying the liquid
agent onto the main surface of the substrate while a substrate
surface facing the liquid agent supply nozzle remains in a convex
form.
[0029] The first step may include a step of supplying the liquid
agent while reducing pressure in a space provided between the
substrate and the liquid agent supply nozzle.
[0030] The liquid agent may be one selected from the group
consisting of a developer, an etching solution, a washing solution,
a remover agent, a film formation solution and a plating
liquid.
[0031] It is desirable that the substrate processing method further
comprise a step of simultaneously rinsing the liquid agent holding
member and the main surface of the substrate by replacing the
liquid agent with a rinse solution after the third step.
[0032] The reciprocating movement or rotational movement in
parallel to the main surface of the substrate may be performed by
any one of the steps: (a) the liquid agent holding member is moved
while the substrate is fixed; (b) the substrate and the liquid
agent holding member are relatively moved to each other in the same
direction; (c) the substrate and the liquid agent holding member
are relatively moved in a reverse direction to each other; and (d)
the substrate or the liquid agent holding member is moved back and
forth, while the other is rotated.
[0033] The substrate processing apparatus according to a second
aspect of the present invention comprises:
[0034] a table on which a substrate is to be mounted;
[0035] a liquid agent supply nozzle for supplying a liquid agent
onto a main surface of the substrate;
[0036] a liquid agent holding member facing the substrate and
movable up and down in order to be in contact with an upper surface
of the film-form liquid agent; and
[0037] a mechanism for moving at least one element of the substrate
and the liquid agent holding member in parallel to the main surface
of the substrate while the liquid agent holding member is in
contact with the upper surface of the film-form liquid agent.
[0038] The liquid agent supply nozzle may serve as the liquid agent
holding member.
[0039] The mechanism desirably includes a reciprocating drive
mechanism or a rotational drive mechanism.
[0040] The liquid agent supply nozzle desirably has a plurality of
liquid agent outlet holes in a surface facing the substrate, any
two of the liquid agent outlet holes adjacent to each other in a
moving direction of the substrate passing through different regions
of the substrate when the nozzle moves relative to the
substrate.
[0041] The liquid agent supply nozzle has a plurality of liquid
agent outlet holes in a surface facing the substrate, the liquid
agent outlet holes being uniformly distributed in a plane facing
the substrate.
[0042] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0043] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate presently
preferred embodiments of the invention, and together with the
general description given above and the detailed description of the
preferred embodiments given below, serve to explain the principles
of the invention.
[0044] FIG. 1 is an example of an entire structure of a system of a
coating/developing apparatus of the present invention including
peripheral units;
[0045] FIG. 2 is a schematic cross-sectional view of a development
unit according to Embodiment 1 of the present invention;
[0046] FIG. 3 is a schematic plan view of a development unit
according to Embodiment 1 of the present invention;
[0047] FIG. 4A is a perspective plan view of a disk nozzle of the
development unit according to Embodiment 1;
[0048] FIG. 4B is a cross sectional view taken along the line 4B-4B
of FIG. 4A;
[0049] FIG. 5 is a characteristic graph showing the dependency of
the measured dimensions of patterns on a wafer upon the wafer
rotation velocity, in Embodiment 1;
[0050] FIG. 6 is a schematic sectional view of the disk nozzle and
the wafer for showing the relationship between the wafer rotation
velocity (VW) and the rotation velocity (VD) of the developer;
[0051] FIG. 7 is a schematic sectional view of the development unit
according to Embodiment 2 of the present invention;
[0052] FIG. 8 is a schematic plan view of the development unit
according to Embodiment 2;
[0053] FIGS. 9A and 9B are a cross sectional view and a bottom
view, respectively, of the linear nozzle according to Embodiment 2
for explaining the structure thereof;
[0054] FIGS. 10A and 10B are perspective views sequentially showing
the developer coating method according to Embodiment 2;
[0055] FIGS. 11A and 11B are a cross sectional view and a front
view, respectively, of another example of the nozzle according to
Embodiment 2, whose developer supply section is a slit;
[0056] FIGS. 11C-11G are cross sectional views showing modified
examples of FIG. 11A, which supply the developer not only in the
downward direction but also in the opposite direction to the nozzle
moving direction;
[0057] FIG. 11H is a perspective view of a nozzle having a
plurality of small passages between a developer storing portion and
a slit, as a still another example of Embodiment 2;
[0058] FIG. 12 is a cross sectional view of a linear nozzle and a
wafer according to a modified example of Embodiment 2, for
explaining a method how to stir the developer by the linear
nozzle;
[0059] FIG. 13A is a schematic plan view of the liquid agent
holding member of a development unit according to Embodiment 3 of
the present invention;
[0060] FIG. 13B is a cross sectional view taken along the line
11B-11B of the FIG. 11A;
[0061] FIG. 14 is a plan view of a conventional disk nozzle, for
showing the position of an outlet hole;
[0062] FIG. 15 is a partial plan view of a substrate for showing a
developing region of the substrate in the case where the disk
nozzle of FIG. 14 is used;
[0063] FIG. 16 is a plan view of a disk nozzle according to
Embodiment 4 of the present invention, for showing the position of
the disk nozzle;
[0064] FIG. 17 is a partial plan view of the substrate for showing
a developing region of the substrate in the case where the disk
nozzle of FIG. 16 is used;
[0065] FIG. 18 is a plan view of a modified example of the disk
nozzle according to Embodiment 4;
[0066] FIG. 19 is a plan view of another modified example of the
disk nozzle according to Embodiment 4;
[0067] FIG. 20 is a partial cross-sectional view of a disk nozzle
according to Embodiment 5, for explaining a development method in
which development is initiated by bringing a developer film, which
is formed by the use of surface tension of the developer, to be
contact with the wafer;
[0068] FIG. 21 is a cross-sectional view of the disk nozzle
including peripheral structural elements, explaining that
development is initiated in Embodiment 5 by dropping, onto a wafer
surface, the developer film formed by virtue of the surface
tension;
[0069] FIGS. 22A-22C are sequential cross sectional views of the
disk nozzle according to Embodiment 6, explaining how to prevent
foam generation when the developer film is formed by a disk nozzle
having a slightly protruding center; and
[0070] FIG. 23 is a cross-sectional view of the disk nozzle of the
development unit according to Embodiment 7, explaining how to mount
the developer by evacuating a space between the disk nozzle and the
wafer by means of a liquid and air pump.
DETAILED DESCRIPTION OF THE INVENTION
[0071] Now, embodiments of the present invention will be explained
with reference to the accompanying drawings.
Embodiment 1
[0072] In the developing step of a photosensitive resist pattern of
this embodiment, a developer supply nozzle is used as a liquid
agent holding member, and a developer is stirred by rotational
motion in a direction parallel to a wafer surface. FIG. 1 shows an
example of a system used in Embodiment 1. The system comprises a
coating/developing apparatus and peripheral apparatuses (exposure
apparatus and the like).
[0073] The coating/developing apparatus is composed of a cassette
station 101, a processing station 102, and an interface section
103. The coating/developing apparatus 104 is connected to an
exposure apparatus 104 by the interface section 103.
[0074] The cassette station 101 is designed to load and unload a
wafer cassette (not shown) into and from the system. The wafer
cassette stores a plurality of substrates, more specifically,
semiconductor wafers (not shown, hereinafter referred to as
"wafers"). The cassette holds, for example, 25 wafers at a time.
The cassette station 101 is designed also to load wafers from the
wafer cassette into the processing station 102, and vise versa.
[0075] The process station 102 has various single wafer processing
units, each designed to process one wafer at a time in the
developing and coating steps. The processing units are arranged one
above another, in stages. Each processing unit processes wafers,
one by one. The process station 102 is composed of a coating unit
105, a development unit 106, and an oven-type processing unit 107.
The coating unit 105 and the development unit 106 are spinner type
units, in which a predetermined treatment is applied to the wafer
mounted on a spin chuck placed in a cup. The unit 105 coats a wafer
with a resist film and an anti-reflection film. The unit 106
develops the resist film.
[0076] The oven-type processing unit 107 is designed to perform a
predetermined treatment on the wafer mounted on a table. The unit
107 includes a cooling unit 108, an adhesion unit 109, an alignment
unit 110, an extension unit 111, a pre-baking unit 112, a
post-exposure baking unit 113, and a baking unit 114. These units
108 to 114 are stacked, one upon another. The cooling unit 108
cools wafers. The adhesion unit 109 performs hydrophobic treatment
to enhance resist adhesion. The alignment unit 110 is designed to
align wafers. The pre-baking unit 112 is provided for heating
wafers prior to light exposure. The post-exposure baking unit 113
is used to heat wafers after light exposure treatment. In the
interface section 103, wafers are transferred from the processing
station 102 to the exposure apparatus 104, and vice versa.
[0077] The wafer is processed as follows. At first, a predetermined
number of wafers are loaded into the wafer cassette. The wafer
cassette holding the wafers is set at the cassette station 101. A
wafer is transported from the cassette station 101 to the cooling
unit 108 which is provided in the oven-type processing unit 107.
The wafer is cooled in the cooling unit 108 for 40 seconds and then
transported to the anti-reflection film coating unit 105. In the
unit 105, the wafer is coated with an anti-reflection film having a
thickness of 60 nm. The wafer is further transported to the baking
unit 114 heated to 175.degree. C. within the oven-type processing
unit 107. In the baking unit 114, the wafer is heated for 60
seconds.
[0078] Thereafter, the wafer is transported to the cooling unit 108
and cooled at 23.degree. C. for 60 seconds. The wafer thus cooled
is transported to the resist coating unit 105. In the unit 105,
resist is applied onto the wafer, and a positive type
photosensitive resist is applied onto the wafer, forming a film
having a thickness of 0.3 .mu.m. Thereafter, the wafer is
transported to the pre-baking unit 112 heated to 100.degree. C.
which is provided in the oven-type process unit 107. In the unit
112, the wafer is pre-baked 90 seconds.
[0079] The wafer thus pre-baked is transported to the cooling unit
108 and is cooled at 23.degree. C. for 60 seconds. The wafer is
then transferred to the interface section 103 and then loaded into
the exposure apparatus 104. The wafer is exposed to light under
normal conditions: NA=0.55, .sigma.=0.55. Thereafter, the wafer is
introduced into the coating/developing apparatus through the
interface section 103 and then heated at 100.degree. C. for 90
seconds in the post exposure baking unit 113.
[0080] The development unit according to this embodiment will be
described.
[0081] FIGS. 2 and 3 are, respectively, cross-sectional view and
plan view of the developing unit incorporated in the
coating/developing apparatus of the present invention. A circular
cup CP is provided at a center portion of the development unit. The
cup CP contains a spin chuck 201. A motor 202 is provided to rotate
the spin chuck 201, while the wafer is held by vacuum adsorption.
The driving motor 202 is fitted in an opening made in the bottom
plate 203 of the developing unit. The motor 202 is connected to a
driving means 205 (including for example, an air cylinder) and a
guiding means 206 by a cap-shaped aluminum flange member 204.
Hence, the motor 202 can be moved up and down. A cylinder-form
cooling jacket 207 made of, e.g., SUS, is fixed to a side of the
driving motor 202. The flange member 204 is fixed, covering the
half of the cooling jacket 207.
[0082] To apply the developer to the wafer, the lower edge of the
flange member 204 is brought into airtight contact with the outer
periphery of the opening made in the unit bottom plate 203. The
developing unit is thereby sealed airtight. To transfer the wafer W
between the spin chuck 201 and the wafer transfer mechanism (not
shown), the flange member 204 is lifted apart from the unit bottom
plate 203 by the driving means 205. In this manner, the driving
motor 202 and the spin chuck 201 are lifted, together with the
flange member 204.
[0083] A developer supply pipe 209 connects a developer supply
nozzle 208 to a developer source (not shown). Developer can
therefore be supplied from the nozzle 208 to the surface of the
wafer surface. The nozzle 208 is removably attached to a distal end
of a nozzle scan arm 210 by a nozzle holder 211. The scan arm 210
is secured to an upper end of a vertical support member 213. The
support member 213 can move along a guide rail 212, which is
provided on the unit bottom plate 203 in a direction Y direction.
Thus, the member 213 can move in the Y direction when driven by a
Y-direction drive mechanism (not shown).
[0084] The developer supply nozzle 208 has substantially the same
shape as the wafer W, as is shown in FIG. 3. More specifically, the
developer supply nozzle 208 is shaped like a disk, slightly larger
than the wafer W. While the wafer W is being rotated, the developer
is supplied from the disk-shaped developer supply nozzle (disk
nozzle) 208, over the entire surface of the wafer W. The nozzle 208
is attached to the distal end of the nozzle scan arm 210, as
described above. The nozzle 208 moves back and forth on the guide
rail 212 in the Y direction, between a position, where it faces the
wafer W, and a stand-by position 214. The stand-by position 214 is
at a side of the wafer W, as is illustrated in FIG. 3. Instead, the
stand-by position 214 may be provided above the wafer W.
[0085] A rinse nozzle 215 is provided for discharging a washing
solution. The rinse nozzle 215 is secured to a distal end of the
nozzle scan arm 216, which can move on the guide rail 212 in the Y
direction. After completion of the developing process with the
developer, the rinse nozzle 215 is moved over the wafer W to apply
the washing solution to the wafer W.
[0086] How the developing process is performed in the developing
unit 106 will be explained.
[0087] After the post exposure baking process described above, the
wafer W is transferred to the developing unit 106 (FIG. 1). In the
unit 106, the wafer is fixed onto the spin chuck 201. The developer
supply nozzle 208, which has substantially the same shape as the
wafer W, is located above the wafer W and faces the wafer W. The
nozzle 208 has a plurality of holes of 0.5 mm in diameter, in the
surface that opposes the wafer W. The holes are arranged at
intervals of 4 mm. The nozzle 208 is spaced by a distance of 2 mm
from the upper surface of the wafer W.
[0088] First, the disk-shaped developer supply nozzle 208 applies
the developer to the entire surface of the wafer W, while the wafer
W is being rotated at 60 rpm. A developer film is thereby formed on
the wafer W to a thickness of 2 mm.
[0089] The state at this time point is shown in FIGS. 4A and 4B.
FIG. 4A is a partial perspective plan view of the development unit.
FIG. 4B is a cross-sectional view of the development unit taken
along the line 4B-4B of FIG. 4A. The space between the disk nozzle
208 and the wafer W is filled with the developer in the form of the
developer film 244, and thus the lower surface of the disk nozzle
208 comes into contact with the upper surface of the developer film
244.
[0090] Next, development is performed for 60 seconds, from the
start of the application of developer to the start of application
of rinse solution supply. During the development, the wafer is
rotated at 30 rpm and the disk nozzle 208 remains at a standstill.
Thereafter, the disk nozzle 208 is lifted to the stand-by position
214 as shown in FIG. 3.
[0091] Then, the rinse nozzle 215 is moved to the center of the
wafer W. The wafer W is rotated at 2000 rpm. The developer is
thereby removed from the wafer. At the same time, the rinse
solution is applied, and the development step is terminated.
Thereafter, the wafer is rotated at 500 rpm to wash the wafer W.
Finally, the supply of the rinse solution is terminated. The wafer
W is rotated at 2000 rpm again, removing the rinse solution from
the wafer W. Thus, the wafer W is dried.
[0092] As a result, a 0.225 .mu.m L&S (line and space) pattern
is formed. The line width (critical dimension) of the L&S
pattern thus formed is measured all over the wafer and the-line
width (dimension) variation (3.sigma.) is calculated. FIG. 5 shows
the dependence of the variation 3.sigma. on the rotation velocity
at which the wafer W is rotated while the developer film remains in
contact with the lower-surface of the nozzle during development. In
FIG. 5, the Y axis indicates the dimension variation 3.sigma. (nm),
and the X axis indicates the rotational velocity (rpm). As seen
from FIG. 5, the dimension variation 3.sigma. has the minimum value
of 8 nm when the wafer is rotated at a rotational velocity ranging
from 30 rpm to 40 rpm during the development. If the wafer W is not
moved at all, the variation 3.sigma. is 20 nm. In the case of the
conventional method, the space between the nozzle and the wafer is
set sufficiently wide for the developer liquid film applied onto
the wafer not to be brought into contact with the nozzle and the
wafer is stopped during development. In this case, the variation
3.sigma. is 23 nm, which is shown in FIG. 5 as "disk nozzle
noncontact development". As FIG. 5 shows, it turns out that the
developer can be stirred and the uniformity of the pattern
dimensions can be improved, by rotating the wafer at an appropriate
velocity (10-50 rpm, preferably 30-40 rpm) during the development,
while the developer film remains in contact with the lower surface
of the nozzle.
[0093] The effect of this method on the uniformity improvement in
resist pattern dimensions is not limited to the L&S pattern
whose line and space width is 0.225 .mu.m. It can also be achieved
for any other patterns. This advantage is attained, regardless of
types and sizes of patterns and can be seen in all patterns.
[0094] Results that may be obtained by using an ultrasonic
oscillator will be described. A developer film is formed on the
wafer by using the disk nozzle. Then, the ultrasonic oscillator
applies ultrasonic waves to the wafer for 50 seconds, while a disk
which has a bottom surface of the same shape as the wafer and which
incorporates the ultrasonic oscillator remains in contact with the
upper surface of the developer liquid film. The disk is withdrawn,
and the wafer is rinsed and dried in the same manner as mentioned
above. In this case, the variation 3.sigma. is 30 nm. This value is
greater than in the case where the wafer is rotated at a low
velocity while the lower surface of the nozzle remains in contact
with the developer liquid film. The value is greater also than in
the case where the developer is supplied by the nozzle that does
not contact the developer film while the wafer is not rotated
during the development. Obviously, the uniformity of the wafer
surface obtained after the development cannot be improved even if
the ultrasonic oscillator is used. This is perhaps because the
liquid agent is not always uniformly in contact with the surface of
the substrate since voids are generated or destroyed in the liquid
agent contacting the substrate, by the cavitation effect resulting
from the vibration.
[0095] During the aforementioned development stirring, the wafer is
rotated at a low speed and the disk nozzle in contact with the
upper surface of the developer liquid film remains at a standstill.
The stirring may be performed as will be explained with reference
to FIG. 6, which is a partial sectional view of the development
unit.
[0096] If the upper surface of the developer does not contact the
disk nozzle, the developer follows the rotational motion of the
wafer. As a result, the developer is not stirred. In addition to
that the developer flows outwardly due to centrifugal force, and
the developer liquid film has no uniform thickness, therefore the
uniformity in the pattern dimensions over the wafer decreases. If
the upper surface of the developer liquid film 244 contacts the
lower surface of the disk nozzle 208 as shown in FIG. 6, friction
is generated between the developer liquid film 244 and the lower
surface of the disk nozzle 208. The friction between the developer
liquid film 244 and the lower surface of the disk nozzle 208
prevents the developer liquid film 244 from moving together with
the wafer W. Consequently, the rotational velocity of the developer
liquid film 244 is lower than that of the wafer W. The liquid film
244 therefore moves relative to the wafer W. This prevents the
local accumulation of the reaction products and local consumption
of the starting liquid agent in the developer liquid film 244 that
contacts the wafer W, which can happen depending upon the
photosensitive pattern.
[0097] Furthermore, the rotational velocity VD of the developer
liquid film 244 near the wafer W is higher than the rotational
velocity VD near the disk nozzle 208, because the wafer W has the
rotational velocity VW and the nozzle 208 remains at a standstill.
Consequently, the moving rate of the developer at the upper portion
of the developer film differs from that at the lower portion of the
developer film, as is illustrated in FIG. 6. Thus, it is presumed
that stirring effect within the developer film has also
developed.
[0098] In the present invention, the liquid agent is stirred by
moving the upper and lower surfaces of the liquid agent film at
different speeds. It is therefore possible to move the liquid agent
over a large area. If an ultrasonic oscillator is used, the liquid
agent is slightly stirred, and the movement of the liquid agent is
limited to a small area. With the method of the present invention
it is possible to stir the liquid agent in a large area. The method
can therefore effectively render the concentrations of the starting
liquid agent and reaction products uniform. The spilling of the
developer 244 due to the centrifugal force and non-uniformity in
the thickness of the liquid film can be prevented by the friction
between the disk nozzle 208 and the developer film 244, by contact
of the disk nozzle with the liquid film with rotating the wafer W
at an appropriate velocity. Hence, a developed wafer having uniform
dimensions can be obtained.
[0099] In the aforementioned explanation, the wafer is rotated in a
plane parallel to the wafer surface. If the wafer is moved relative
to the liquid agent holding member (developer supply nozzle or disk
nozzle), the same advantages as mentioned above can be obtained.
Therefore, the wafer may be maintained at a standstill, whereas the
developer holding member is moved. Alternatively, both the holding
member and the wafer may be moved in the same direction or in the
opposite directions.
[0100] The wafer is rinsed by using a straight-tube rinse nozzle in
the aforementioned embodiment. Instead, a disk nozzle may be used
to rinse the wafer. Especially, in the case that the liquid agent
supply nozzle acts also as the liquid agent holding member, it is
effective. The nozzle surface can also be washed during the step of
rinsing the wafer if the rinse solution is supplied from the same
nozzle to the wafer, and the rinse solution contacts the nozzle for
a certain time. The step to separate the nozzle from the liquid
agent is needed to remove the rinse solution from the space between
the nozzle and the wafer.
Embodiment 2
[0101] Embodiment 2 of the invention will be explained with
reference to FIGS. 7 and 8.
[0102] FIGS. 7 and 8 are sectional view and plan view of an entire
structure of a development unit, respectively. The developing unit
has a linear nozzle 271, which has a linear developer supply
section whose length is almost same as a diameter of the wafer. A
developer holding member 272 is attached to the unit in addition to
the developer supply nozzle 271. The member 272 faces the wafer W,
and can be used to sandwich the developer between the member and
the wafer. The developer holding member (stirring member) 272 is
attached to the distal end of a holding member scan arm 274. The
arm 274 is a drive mechanism that can move on a guide rail 273 in
the Y direction. The developer holding member 272 moves between a
stand-by position and a position where it faces the wafer W.
[0103] The developer supply nozzle 271 is attached to the nozzle
scan arm which is secured to a supporting shaft 275, which is fixed
at a position different from the guide rail 273. The developer
supply nozzle 271 moves toward or away from a position near the
wafer W when the nozzle scan arm is moved upwards or downwards.
Alternatively, the supporting shaft supporting the nozzle scan arm
may be mounted on another guide rail which is provided at some
distance from the guide rail 273 and may move on another guide
rail.
[0104] The linear nozzle has at least a developer storing portion
and a linear developer supply section. The developer storing
portion stores the developer supplied by developer supply tubes.
The developer supply section has almost the same length as a
diameter of the wafer. FIGS. 9A and 9B show one example of the
linear nozzle, which are used in this embodiment. There is a
developer-storing portion like a box container inside the nozzle.
The center portion of the bottom protrudes as shown in FIG. 9A.
There is the developer supply section at the protruded portion. The
developer supply section is made of small holes (developer outlet
holes) arranged in a line. The diameter of the holes is 0.4 mm and
the interval between the adjacent two holes is 2 mm. The developer
supply section has almost the same length as the diameter of the
wafer. The length of the developer supply section is not needed to
be longer than the diameter of the wafer, because the developer
spreads after discharge from the nozzle holes. The width of the
nozzle is approximately 35 mm. After the developer is stored in the
developer storing portion, the developer is supplied on the wafer
as it seeps through the small holes (developer outlet holes) on the
bottom of the nozzle.
[0105] After post-exposure baking has been performed in the same
way as in Embodiment 1, the wafer W is moved into the development
unit and held immovable by the spin chuck.
[0106] The nozzle 271 first moves downwards as the arm 276 moves
down. The protruding portion of the nozzle bottom is spaced apart
from the wafer by a distance of 2 mm. While the wafer is being
rotated at 1000 rpm for 2 seconds, the developer is applied from
the nozzle and spread over the surface of the wafer W. Then, the
developer is supplied to the wafer while the wafer W is being
rotated at 30 rpm for 2 seconds, forming a developer liquid film on
the wafer W as shown in FIG. 10A. The linear nozzle 271 is lifted
as the arm 276 moves upwards.
[0107] The developer holding member 272 is moved to face the wafer
as the scan arm 274 moves along the guide rail 273. The member 272
is then moved down until it contact the developer. The development
is performed for 45 seconds, while the wafer is being rotated at 30
rpm as shown in FIG. 10B. The development time of 45 seconds has
been determined so that a period of 60 seconds passes from the
start of applying the developer to the start of applying the rinse
solution. This period includes the time (5 seconds) for moving the
nozzle and the developer holding member and the time (6 seconds)
for moving the developer holding member and the rinse nozzle. The
development time may be changed in accordance with the development
conditions.
[0108] The developer is held by the developer holding member 272
between the wafer and the developer holding member 7, instead of
the development nozzle 208 shown in FIG. 4B. The same advantages
can be obtained as in Embodiment 1.
[0109] Thereafter, a rinse solution is supplied with the wafer
rotated at 2000 rpm, whereby the developer is removed from the
wafer W, and the development is thus terminated. The wafer W is
washed with a rinse solution while the wafer is being rotated at
500 rpm. Finally, the supply of the rinse solution is stopped, and
the wafer W is rotated at 2000 rpm, whereby the rinse solution is
removed from the wafer W, and the wafer W is dried.
[0110] In this case, the line width (dimension) variation
(3.sigma.) over a wafer was 8 nm for an L&S pattern whose line
width and space width is 0.225 .mu.m, as in the first embodiment.
Obviously, if the developer liquid film contacts the developer
holding member and if the wafer is rotated at an appropriate
rotation number, the developer can be stirred to improve the
pattern dimension uniformity.
[0111] The developer holding member has the same shape as the wafer
W. Nonetheless, the developer holding member may have a different
shape.
[0112] Further, the linear developer nozzle 271 having a number of
small holes may be replaced by other types of linear nozzle. The
developer supply section may be made of a narrow slit or made of
plural openings like ellipses or slits. For example, FIGS. 11A and
11B show a developer supply section having a narrow slit.
Otherwise, a nozzle supplying the developer in the opposite and
downward direction of the nozzle movement, in stead of supplying
the developer downwards just below the nozzle, may be used, as
shown in FIGS. 11C-11G. In addition to those, a nozzle that has
small passages between the developer storing portion and the
developer supply section may be used, as shown in FIG. 11H. The
role of the small passages is to make the pressure of the developer
uniform. Alternatively, a disk nozzle or parallel nozzles may be
used to apply the developer to the wafer W. Furthermore, any other
types of developer supply nozzles may be employed.
[0113] As indicated above, the developer is applied to the rotating
wafer W from the nozzle 271 that has been immobilized. Instead, the
developer may be applied onto the immobilized wafer from a linear
nozzle whose developer supply section has the same length as the
wafer diameter, while the nozzle being moved over the wafer, in one
direction parallel to the wafer W from one side to the other.
[0114] The stand-by position for the developer holding member may
be set above the wafer W, not at one side of the wafer as described
above.
[0115] In Embodiment 1, the developer is supplied from the disk
nozzle and then stirred by the disc nozzle. In Embodiment 2, the
developer is supplied from the linear nozzle and stirred by the
developer holding member. The present invention is not limited to
these embodiments. The nozzle which has such a shape as to hold the
developer can be used not only to apply the developer but also to
stir the developer. A modified embodiment, which has a linear
nozzle, will be explained below.
[0116] The nozzle 271 used in the modified embodiment is similar to
the nozzle incorporated in Embodiment 2, but has its lower edge
located at a distance of 0.5 mm from the upper surface of the wafer
W. The lower end of the nozzle 271 can therefore contact the
developer applied to the wafer W. After the developer is supplied
onto the wafer in the same manner as in Embodiment 1, the wafer is
continuously rotated at 30 rpm. The wafer is developed for 50
seconds while being rotated as mentioned above. The development
time of 50 seconds has been determined so that a period of 60
second may pass from the start of application of the developer to
the start of application of the rinse solution. The 60-second
period includes the time of 4 seconds for applying the developer
and the time of 6 seconds for moving the nozzle and the rinse
nozzle. Thus, the developer is held between the nozzle bottom and
the wafer as shown in FIG. 12. The same advantages can be obtained
as in Embodiment 1.
Embodiment 3
[0117] Embodiment 3 will be explained with reference to FIGS. 13A
and 13B.
[0118] As shown in FIGS. 13A and 13B, the developer applied to the
wafer W can be effectively stirred by moving the developer holding
member 291 in parallel to the wafer surface. For example, a guide
rail is provided in the same manner as shown in FIGS. 7 and 8. The
developer holding member 291 is secured to a drive mechanism, which
can freely move on the guide rail, enabling the holding member to
move between a stand-by position and a position where the holding
member faces the wafer. The holding member must be moved repeatedly
at high speed during the development process. Therefore, a motor
drives the holding member to move at a sufficiently high speed.
[0119] In FIGS. 13A and 13B, a developer holding board is provided
which is larger than the wafer is used to stir the developer. The
holding board may be replaced by a holding board smaller than the
wafer.
[0120] Embodiments 1 to 3 show the case that at least one element
of the wafer and the developer holding member is rotated or
reciprocated in parallel to the main surface of the substrate. Of
course, one of the wafer and the developer holding member may be
rotated and the other may be reciprocated in parallel to the main
surface of the substrate.
Embodiment 4
[0121] Embodiment 4 of the present invention will be described with
reference to FIGS. 14 to 19.
[0122] FIG. 14 is a plan view of a conventional disk nozzle
(developer supply nozzle) 1000 which has outlet holes. FIG. 15 a
partial plan view of the development region 1105 of a wafer, over
which an outlet hole shown in FIG. 14 passes. FIG. 16 is a plan
view of a disk nozzle 1200 according to Embodiment 4, which has
outlet holes. The disk nozzle 1200 corresponds to the portion 208
in Embodiment 1. FIG. 17 is a partial plan view of the development
region 1205 of the wafer, over which the outlet holes shown in FIG.
16 passes. FIGS. 18 and 19 show two modifications of the disk
nozzle 1200, which differ in the arrangement of the outlet holes.
In FIGS. 14, 16, 18, and 19, the broken circles facilitate the
arrangement of the outlet holes.
[0123] As shown in FIG. 14, the conventional disk nozzle 1000 has a
plurality of outlet holes 1002, 1003, 1004 . . . . The outlet holes
are arranged in concentric circles. If the developer is applied to
a wafer by the conventional disk nozzle 1000, however, the wafer
will fail to have uniform pattern dimensions over the wafer. This
is because the developer present in each outlet hole and the
developer existing at the upstream of the outlet hole will diffuse
into each other, especially at that portion of the wafer which is
located right below the outlet hole. The developer applied at this
portion is fresher than the developer applied to the other portions
of the wafer. As a consequence, the wafer is developed faster at
the portions right below the outlet holes than at the other
portions.
[0124] Even if the wafer is rotated around the nozzle 1001, outlet
holes 1002, 1003, 1004 . . . pass over a limited region 1106 of the
wafer 1105. The wafer 1105 is inevitably developed at high rate at
this limited region as shown in FIG. 15. Therefore, the improvement
of the uniformity in film thickness cannot be attained.
[0125] On the other hand, the outlet holes of the disk nozzle 1200
according to the present invention are arranged as shown in FIG.
16. In FIG. 16, the outlet holes 1202, 1203, and 1204 are arranged
such that they do not pass in a limited region while the wafer is
being rotated (during the stirring process). When the disk nozzle
1200 is used, a region through which the outlet hole 1202 passes
shifts from those regions through which the outlet holes 1203 and
1204 passes as shown in FIG. 17.
[0126] In addition, the outlet holes pass through the region 1202
to 1204 far less frequently than the holes of the conventional disk
nozzle 1000 (FIG. 14). Hence, the disk nozzle 1200 serves to
improve drastically the pattern dimension uniformity over the
wafer. When the developer is applied from the outlet holes, the
wafer receives pressure at the portions located immediately below
the outlet holes, which impair the pattern dimension uniformity. To
prevent this, the pressure below the outlet holes should be as
small as possible. The total amount of the developer supplied onto
the wafer is predetermined. So it is desirable that the amount of
supplied developer per hole is less and the number of the holes is
more when the developer is supplied in the predetermined time.
[0127] In Embodiment 4, the disk nozzle 1200 serves also as a
developer holding member. Nonetheless, a developer holding member
may be provided, besides the disk nozzle 1200. If so, the pH value
the developer has at a position right below an outlet hole differs
from the pH value the developer has at any position far from the
outlet hole. To improve the dimension uniformity of the pattern
formed on the wafer, the output holes should be arranged as shown
in FIG. 16, more preferably as shown in FIGS. 18 and 19.
Furthermore, it is desirable that the outlet holes is distributed
uniformly over the entire disk nozzle 1200.
[0128] In Embodiment 4, a developer film is formed by applying the
developer from the entire lower surface of the disk nozzle 1200,
while the wafer is rotated at low speed. However, the method of
forming a film is not limited to this. A mechanism for suppressing
foams (cause of defects) which are generated in the developer after
the developer is applied to the wafer, and a mechanism for
supplying a developer to the entire wafer at the almost same time
may be used as in Embodiments 5, 6 and 7, which will be described
below.
Embodiment 5
[0129] Embodiment 5 will be explained with reference to FIGS. 20
and 21.
[0130] FIG. 20 is a sectional view of a disk nozzle, explaining
that a developing process is initiated by bringing a developer film
(formed by virtue of the assistance of surface tension) into
contact with a wafer. To develop a resist film provided on the
surface of a substrate such as a wafer, the developer film is
formed on the surface of the disk nozzle by virtue of the surface
tension. Then, the developer film is made in contact with the
wafer, thereby initiating the development. The developer is applied
to the entire surface of the wafer at a time. Air may remain in a
space between the surface of the developer liquid film and the
surface of the resist, but no fine foams are generated on the wafer
surface. The foams generated at this time are large enough to rise
to the upper surface of the developer liquid film. The developer
liquid film, therefore, has no defects.
[0131] In the development unit, the developer may be slightly
forced from the nozzle holes 1601 by the pressure applied before
the start of the development process. If so, adjacent developer
droplets from adjacent nozzle holes 1601 combine together due to
the surface tension, forming a developer film 1602 on the nozzle
surface (FIG. 20).
[0132] Subsequently, the wafer having a latent image formed on its
surface is lifted, together with a wafer holder (not shown), until
it contacts the developer liquid film 1602. The development is
thereby initiated. In this process, the developer is applied to the
entire region of the wafer, which is to be processed in a moment.
Then the developer is supplied through the nozzle holes as the
distance between the wafer and the nozzle is widened with the
contact between the developer and the nozzle. At last, the desired
amount of the developer is discharged on the wafer and the distance
is set at the predetermined distance.
[0133] After the developer has been applied to it, the wafer is
moved relative to the disk nozzle holding the developer, as in
Embodiments 1 to 4. Upon lapse of 60 seconds from the start of the
development, the disk nozzle is moved up, and rinse solution is
applied to the wafer, terminating the development. After rinsed
thoroughly, the wafer is rotated at high speed, whereby the rinse
solution is removed from the wafer. Post-baking is performed on the
wafer at 130.degree. C. for 90 seconds. The wafer is taken from the
developing unit.
[0134] In the above explanation, the wafer is moved up to contact
the developer film. Nevertheless, the development may be initiated
by dropping the developer liquid film onto the wafer, as shown in
FIG. 21, by supplying air through the holes of the disk nozzle
connected to an air supply system, after the developer liquid film
has been formed.
[0135] In the above development process, the nozzle is moved to a
predetermined distance, while the disk nozzle remains in contact
with the developer and while the developer is applied to the wafer
from the developer supply system through the nozzle holes, after
the wafer has come in contact with the developer film. Instead,
after the wafer has come in contact with the developer film, the
distance between the wafer and the nozzle may be set at the
predetermined distance and then the space may be filled with the
developer.
Embodiment 6
[0136] Embodiment 6 will be explained with reference to FIGS. 22A
to 22C.
[0137] FIGS. 22A to 22C are sectional views of a disk nozzle having
a center portion slightly protruding. A method of developing wafer
by using this disk nozzle will be explained.
[0138] To prevent generation of foams during the process of forming
a developer film, it is effective to employ a disk nozzle having a
center portion that protrudes slightly. Air is forced out from the
developer, thereby preventing foams from being made when the
developer is mounted on the wafer.
[0139] The wafer having a latent image formed on it is transported
into the development unit. A disk nozzle 1801 is used, which is
circular as viewed from the bottom. The center part of the disk
nozzle 1801 slightly protrudes, as shown in FIG. 22A.
[0140] The disk nozzle 1801 is spaced from the wafer by a distance
of 2 mm. Developer 1800 is applied onto the wafer as shown in FIG.
22B. At the same time, the wafer is rotated at 60 rpm, whereby the
developer spreads itself over the entire surface of the wafer. The
developer 1802 is applied until it contacts the disk nozzle 1801,
forming a film 1802 as is illustrated in FIG. 22C.
[0141] During the development step, the wafer of the present
invention is moved relatively to the disk nozzle holding the
developer in the same manner as explained in Embodiments 1 to 4.
Upon lapse of 60 seconds from the start of the development, the
disk nozzle 1801 is moved up, and rinse solution is applied to the
wafer, thereby terminating the development process. After
thoroughly rinsed, the wafer is rotated at high speed, whereby the
rinse solution is removed from the wafer. The post-baking is
performed on the wafer at 130.degree. C. for 90 seconds. The wafer
is taken from the development unit.
[0142] Since the surface of the disk nozzle is curved, a space is
provided in the wafer peripheral region between the nozzle surface
and the wafer surface. Air is forced out through this space. No
foams are generated. Therefore, the number of defects is reduced
after completion of the development.
[0143] As described above, the developer is supplied from the
nozzle holes, directly to the wafer. Instead, the developer liquid
film formed on the surface of the nozzle may be set into contact
with the wafer to initiate the development, as in Embodiment 5.
Alternatively, the developer liquid film may be dropped onto the
wafer to start the development, by supplying air from an air supply
system.
[0144] Moreover, the same effect may be expected as the above
embodiment, if the substrate surface facing the nozzle is in a
convex form during the developer supply.
Embodiment 7
[0145] Embodiment 7 will be described with reference to FIG.
23.
[0146] FIG. 23 is a sectional view of a disk nozzle, explaining a
method of applying developer to the wafer by creating a low vacuum
between the disk nozzle and the wafer by use of a liquid/gas
evacuating pump.
[0147] As the way to prevent generation of foams when the developer
is applied, the apparatus provides a cover (wall) between the wafer
and the periphery of the disk nozzle, thereby providing a space and
to connect this space to the liquid/gas evacuating pump. When the
space is evacuated by a liquid/gas pump, generating a vacuum, the
developer is pushed out of the nozzle holes and the developer is
applied from the disk nozzle onto the wafer. The developer is
thereby applied to the entire surface of the wafer almost at a
time. Since air is removed as mentioned above, virtually no foams
are generated in the developer film formed on the wafer.
[0148] A cover 1901 having a height of 2 mm is provided under the
disk nozzle 1903 and on the wafer. The cover 1901 and the disk
nozzle therefore shields, like a cap, the main surface of the
wafer. A part of the cover 1901 is connected with the liquid/gas
pump. Air is drawn from the space provided between the disk nozzle
1903 and the cover 1901 by the evacuation of the space with the
liquid/gas pump. At the same time, the developer 1900 is forced out
from the disk nozzle 1903 through the nozzle holes 1902. The
developer 1900 is thereby applied to the wafer. When the developer
1900 is supplied to a desired amount into the space between the
wafer and the disk nozzle 1903, the liquid/gas pump is stopped.
Then, in order to move the wafer relatively to the cover and the
disk nozzle, the liquid/gas pump is run reversely.
[0149] The wafer W of the present invention is moved relative to
the disk nozzle holding the developer, as in Embodiments 1 to 4.
Upon lapse of 60 seconds from the start of the application of
developer, the disk nozzle 1903 is moved up. A rinse solution is
then applied to the wafer, thereby terminating the development.
After thoroughly rinsed, the wafer W is dried while spinning.
Post-baking is performed on the wafer W at 130.degree. C. for 90
seconds. Then, the wafer W is taken from the development unit.
[0150] To lift the cover and the disk nozzle, the liquid/gas pump
is operated reversely in the aforementioned example. Alternatively,
the liquid/gas pump may be stopped after the developer has been
applied in a desired amount, and additional developer or air is
applied through the nozzle holes, thereby to lift the cover and the
disk nozzle.
[0151] In the embodiments described above, the developer liquid
film is formed directly on the wafer. A liquid film such as a water
film, which cannot develop the film, may be formed before the
formation of the developer liquid film. The developer liquid film
may then be formed, while the liquid film (water film) is being
removed from the wafer. Thus, the dimension uniformity of the
formed pattern can be well improved, and defects can be
reduced.
[0152] As described above, the substrate processed in the
aforementioned embodiments is a semiconductor wafer. Nonetheless,
the method and apparatus of the present invention can be applied to
other substrates, such as a liquid crystal display substrate and an
exposure mask substrate.
[0153] The development process carried out in the embodiments
described above is designed to form a photosensitive resin pattern.
However, the main feature of the invention resides in bringing the
liquid agent holding member into contact with part of the liquid
agent and by moving the holding member or the substrate during the
wet process. The starting reaction materials and the reaction
products in the liquid agent therefore have uniform concentrations
in the region where they contact the substrate surface. So the
dimension uniformity of the pattern formed on the wafer is
improved. Accordingly, the present invention can be applied to a
wet etching process and an apparatus for manufacturing a chromium
exposure mask.
[0154] The stirring method of the invention not only renders the
concentration of the liquid agent uniform all over the substrate
surface, but also reduces the concentration of the reaction
products accumulated on the substrate surface and increases the
concentration of the starting materials of the liquid agent.
Therefore, the processing rate can be also increased.
[0155] As has been described, the method of the present invention
can be used to remove organic materials from a substrate, remove a
photoresist pattern after etching, and remove a native oxide film
from a silicon wafer. The present invention can be applied to Au
plating of a substrate if an electrode is provided on the substrate
and the liquid agent holding member and if a plating solution is
used in place of the liquid agent.
[0156] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
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