U.S. patent application number 17/519785 was filed with the patent office on 2022-02-24 for substrate processing method and substrate processing apparatus.
The applicant listed for this patent is TOKYO ELECTRON LIMITED. Invention is credited to Hitoshi KOSUGI, Kouzou TACHIBANA, Shota UMEZAKI, Ryo YAMAMOTO.
Application Number | 20220059357 17/519785 |
Document ID | / |
Family ID | 1000005947191 |
Filed Date | 2022-02-24 |
United States Patent
Application |
20220059357 |
Kind Code |
A1 |
KOSUGI; Hitoshi ; et
al. |
February 24, 2022 |
SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS
Abstract
A method includes rotating a substrate, supplying a first
processing liquid from a first nozzle to the substrate during a
first period, and supplying a second processing liquid from a
second nozzle to the substrate during a second period. First and
second liquid columns are formed by the first and second processing
liquids during at least partially overlapped period of the first
and second periods, respectively. The shapes and arrangements of
the first and second liquid columns satisfy that: at least one of
first and second central axis lines of the first and second liquid
columns is inclined with respect to a rotational axis line of the
substrate, first and second cut surfaces obtained by cutting the
first and second liquid columns along a horizontal plane at least
partially overlap each other, and any point on the first central
axis line is located on the second central axis line.
Inventors: |
KOSUGI; Hitoshi; (Koshi
City, JP) ; UMEZAKI; Shota; (Koshi City, JP) ;
TACHIBANA; Kouzou; (Koshi City, JP) ; YAMAMOTO;
Ryo; (Koshi City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOKYO ELECTRON LIMITED |
Tokyo |
|
JP |
|
|
Family ID: |
1000005947191 |
Appl. No.: |
17/519785 |
Filed: |
November 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16737526 |
Jan 8, 2020 |
11217451 |
|
|
17519785 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/30604 20130101;
H01L 21/67017 20130101; H01L 21/68764 20130101; H01L 21/306
20130101 |
International
Class: |
H01L 21/306 20060101
H01L021/306; H01L 21/687 20060101 H01L021/687; H01L 21/67 20060101
H01L021/67 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 17, 2019 |
JP |
2019-006171 |
Claims
1-18. (canceled)
19. A substrate processing apparatus, comprising: a substrate
holding/rotating part configured to rotate a substrate around a
vertical axis while holding the substrate in a horizontal posture;
a first nozzle configured to supply a first processing liquid to
the substrate; a second nozzle configured to supply a second
processing liquid to the substrate; a nozzle holder configured to
fixedly hold the first nozzle and the second nozzle so as not to be
movable relative to each other; a liquid receiving cup provided to
surround the substrate and configured to receive at least one of
the first processing liquid and the second processing liquid
scattering from the rotating substrate; a ceiling plate configured
to cover an upper opening of the liquid receiving cup; and an inert
gas supply part configured to supply an inert gas to a space
between the ceiling plate covering the upper opening of the liquid
receiving cup and a front surface of the substrate held by the
substrate holding/rotating part, wherein the nozzle holder is
configured to hold the first nozzle and the second nozzle so that a
first central axis line and a first cut surface of a first liquid
column formed by the first processing liquid discharged from the
first nozzle and a second central axis line and a second cut
surface of a second liquid column formed by the second processing
liquid discharged from the second liquid column discharged from the
second nozzle satisfy the following conditions: at least one of the
first central axis line which is a central axis line of the first
liquid column and the second central axis line which is a central
axis line of the second liquid column is inclined with respect to a
rotational axis line of the substrate; the first cut surface and
the second cut surface obtained by cutting the first liquid column
and the second liquid column along a horizontal plane including the
front surface of the substrate at least partially overlap each
other as viewed in a direction of the rotational axis line; and all
points on the first central axis line are located on the second
central axis line as viewed in the direction of the rotational axis
line.
20. The apparatus of claim 19, wherein the nozzle holder is fixed
to the ceiling plate, or the nozzle holder is configured to be
inserted into an opening formed in a central portion of the ceiling
plate by a nozzle arm configured to support the nozzle holder.
21. The apparatus of claim 19, wherein the first central axis line
is inclined with respect to the vertical axis.
22. The apparatus of claim 21, wherein the first processing liquid
and the second processing liquid are the same kind of processing
liquids or different kinds of processing liquids.
23. The apparatus of claim 19, wherein the first central axis line
is parallel to the vertical axis.
24. The apparatus of claim 23, wherein the first processing liquid
and the second processing liquid are the same kind of processing
liquids or different kinds of processing liquids.
25. The apparatus of claim 19, wherein the first central axis line
and the second central axis line intersect with each other at an
angle of 30 degrees or less.
26. The apparatus of claim 19, wherein a center of the first cut
surface is in the second cut surface, and a center of the second
cut surface is in the first cut surface.
27. The apparatus of claim 19, wherein a distance between a center
of the first cut surface and a center of the second cut surface is
2 mm or less.
28. The apparatus of claim 19, wherein a vertical distance from an
intersection point of the first central axis line with the second
central axis line to the front surface of the substrate is 3 mm or
less.
29. The apparatus of claim 19, wherein the first nozzle and the
second nozzle are fixed to a common nozzle holder so as not to be
movable relative to each other.
30. The apparatus of claim 19, wherein the first processing liquid
and the second processing liquid are the same kind of processing
liquids or different kinds of processing liquids.
31. The method of claim 19, wherein the first nozzle and the second
nozzle are fixed to the ceiling plate so as not to be movable
relative to each other, or the first nozzle and the second nozzle
are fixed to the nozzle holder so as not to be movable relative to
each other, and wherein the nozzle holder is inserted into an
opening formed in a central portion of the ceiling plate.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2019-006171, filed on
Jan. 17, 2019, the entire contents of which are incorporated herein
by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a substrate processing
method and a substrate processing apparatus.
BACKGROUND
[0003] In the manufacture of a semiconductor device, liquid
processing such as liquid chemical cleaning, wet etching or the
like is performed on a substrate. In such a liquid processing, a
plurality of kinds of processing liquids, for example, liquid
chemical (e.g., DHF), a rinse liquid (e.g., DIW), and a drying
liquid (e.g., IPA) are sequentially supplied to the substrate (for
example, see Patent Document 1). Patent Document 1 discloses a
technology in which there is an overlap between the end of a period
during which a rinse nozzle supplies DIW and the start of a period
during which a drying liquid nozzle supplies IPA.
PRIOR ART DOCUMENT
Patent Documents
[0004] Patent Document 1: Japanese Laid-Open Patent Publication No.
2017-108190
SUMMARY
[0005] According to one embodiment of the present disclosure, there
is provided a method of processing a substrate, including: rotating
the substrate around a vertical axis in a horizontal posture;
supplying a first processing liquid from a first nozzle to a front
surface of the rotating substrate during a first supply period; and
supplying a second processing liquid from a second nozzle to the
front surface of the rotating substrate during a second supply
period, wherein the first supply period and the second supply
period at least partially overlap each other, and a first liquid
column is formed by the first processing liquid discharged from the
first nozzle and a second liquid column is formed by the second
processing liquid discharged from the second nozzle during the
overlapped period, and wherein a shape and an arrangement of the
first liquid column, when the discharge of the second processing
liquid from the second nozzle, is assumed as being stopped during
the overlapped period, and a shape and an arrangement of the second
liquid column, when the discharge of the first processing liquid
from the first nozzle, is assumed as being stopped during the
overlapped period, satisfy certain conditions wherein: at least a
second central axis line of a first central axis line, which is a
central axis line of the first liquid column, and the second
central axis line, which is a central axis line of the second
liquid column, is inclined with respect to a rotational axis line
of the substrate; a first cut surface and a second cut surface,
obtained by cutting the first liquid column and the second liquid
column along a horizontal plane including the front surface of the
substrate, at least partially overlap each other as viewed in a
direction of the rotational axis line; and any point on the first
central axis line is located on the second central axis line as
viewed in the direction of the rotational axis line.
BRIEF DESCRIPTION OF DRAWINGS
[0006] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the present disclosure, and together with the general description
given above and the detailed description of the embodiments given
below, serve to explain the principles of the present
disclosure.
[0007] FIG. 1 is a longitudinal sectional view of a substrate
processing apparatus according to an embodiment of the present
disclosure.
[0008] FIG. 2 is a schematic longitudinal cross-sectional view of a
processing unit included in the substrate processing apparatus of
FIG. 1.
[0009] FIG. 3 is a cross-sectional view illustrating arrangement of
nozzles.
[0010] FIG. 4 is a diagram illustrating arrangement of a first
nozzle and discharge of a processing liquid.
[0011] FIG. 5 is a diagram illustrating arrangement of a second
nozzle and discharge of a processing liquid.
[0012] FIG. 6 is a diagram illustrating arrangement of a third
nozzle and discharge of the processing liquid.
[0013] FIG. 7 is a time chart illustrating an example of liquid
processing performed by the substrate processing apparatus in FIG.
1.
[0014] FIG. 8 is a diagram illustrating a related art.
[0015] FIG. 9 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0016] FIG. 10 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0017] FIG. 11 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0018] FIG. 12 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0019] FIG. 13 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0020] FIG. 14 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0021] FIG. 15 is a diagram illustrating a relationship between
processing liquids discharged from two nozzles.
[0022] FIG. 16 is a schematic plan view illustrating a problem
caused by interference between processing liquids discharged from
two nozzles.
DETAILED DESCRIPTION
[0023] A substrate processing system according to an embodiment of
a substrate processing apparatus will now be described with
reference to the drawings. FIG. 1 is a diagram illustrating a
schematic configuration of a substrate processing system. For the
clarification of a positional relationship, an X-axis direction, a
Y-axis direction and a Z-axis direction, which are orthogonal to
one another, are defined in the following description and a
positive Z-axis direction is defined as a vertical upward
direction. In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the present disclosure. However, it will be apparent to one of
ordinary skill in the art that the present disclosure may be
practiced without these specific details. In other instances,
well-known methods, procedures, systems, and components have not
been described in detail so as not to unnecessarily obscure aspects
of the various embodiments.
[0024] As shown in FIG. 1, a substrate processing system 1 includes
a loading/unloading station 2 and a processing station 3. The
loading/unloading station 2 and the processing station 3 are
provided adjacent to each other.
[0025] The loading/unloading station 2 includes a carrier stage 11
and a transfer part 12. A plurality of carriers C each which
accommodates a plurality of substrates, in this embodiment,
semiconductor wafers (hereinafter referred to as wafers W) in a
horizontal posture, are placed on the carrier stage 11.
[0026] The transfer part 12 is provided adjacent to the carrier
stage 1I and includes a substrate transfer device 13 and a delivery
part 14 provided therein. The substrate transfer device 13 includes
a wafer holding mechanism that holds the wafer W. The substrate
transfer device 13 is movable in the horizontal direction and the
vertical direction and swingable around a vertical axis, and
transfers the wafer W between the carrier C and the delivery part
14 using the wafer holding mechanism.
[0027] The processing station 3 is provided adjacent to the
transfer part 12. The processing station 3 includes a transfer part
15 and a plurality of processing units 16. The plurality of
processing units 16 are provided on both sides of the transfer part
15 in a side-by-side manner.
[0028] The transfer part 15 includes a substrate transfer device 17
provided therein. The substrate transfer device 17 includes a wafer
holding mechanism that holds the wafer W. The substrate transfer
device 17 is movable in the horizontal direction and the vertical
direction and swingable around a vertical axis, and transfers the
wafer W between the delivery part 14 and each processing unit 16
using the wafer holding mechanism.
[0029] Each of the processing units 16 performs a predetermined
substrate processing on the wafer W transferred by the substrate
transfer device 17.
[0030] The substrate processing system 1 further includes a control
device 4. The control device 4 is, for example, a computer, and
includes a controller 18 and a storage part 19. The storage part 19
stores a program for controlling various processes to be executed
in the substrate processing system 1. The controller 18 controls
the operation of the substrate processing system 1 by reading and
executing the program stored in the storage part 19.
[0031] The program may be recorded in a non-transitory
computer-readable storage medium and installed from the storage
medium on the storage part 19 of the control device 4. Examples of
the computer-readable storage medium may include a hard disk (HD),
a flexible disk (FD), a compact disk (CD), a magnetic optical disk
(MO), a memory card and the like.
[0032] In the substrate processing system 1 configured as above,
first, the substrate transfer device 13 of the loading/unloading
station 2 takes out the wafer W from the carrier C mounted on the
carrier stage 11 and places the same on the delivery part 14. The
wafer W placed on the delivery part 14 is picked up from the
delivery part 14 by the substrate transfer device 17 of the
processing station 3 and loaded into the processing unit 16.
[0033] The wafer W loaded into the processing unit 16 is processed
by the respective processing unit 16. Thereafter, the processed
wafer W is unloaded from the processing unit 16 by the substrate
transfer device 17, and then placed on the delivery part 14.
Thereafter, the processed wafer W placed on the delivery part 14 is
returned to the carrier C of the carrier stage 11 by the substrate
transfer device 13.
[0034] Next, a configuration of the processing unit 16 will be
described.
[0035] As illustrated in FIG. 2, the processing unit 16 has a
chamber (unit casing) 20. A fan filter unit (FFU) 21 is installed
on a ceiling portion of the chamber 20. The FFU 21 forms a
down-flow inside the chamber 20.
[0036] A substrate holding/rotating part 30, which is referred to
as a spin chuck or the like, is installed inside the chamber 20.
The substrate holding/rotating part 30 includes a chuck 31
(substrate holding element), and a rotary motor 32 configured to
rotate the chuck 31. The substrate holding/rotating part 30 is
configured to rotate the wafer W as a target substrate around a
vertical axis while holding the wafer W in a horizontal posture.
The chuck 31 may be a vacuum chuck which attracts a lower surface
of the wafer W. or may be a mechanical chuck which holds the
periphery of the wafer W by a plurality of gripping claws. The
substrate holding/rotating part 30 includes an elevating mechanism
(not shown), and is configured to move the chuck 31 up and down by
the elevating mechanism.
[0037] Various processing liquids are supplied to the wafer W by a
processing liquid supply part 40. The processing liquid supply part
40 includes a plurality of (three in the illustrated embodiment)
nozzles 41, a nozzle holder 42, a nozzle arm 43, and an arm driving
mechanism 44. The three nozzles 41 are fixed to the nozzle holder
42. The nozzle holder 42 is fixed to a leading end of the nozzle
arm 43. The arm driving mechanism 44 can move the nozzle arm 43 up
and down in the vertical direction and rotate around a vertical
axis 45. Accordingly, the nozzles 41 can move between a processing
position located directly above the center of the wafer W and a
retracted position deviated from above the wafer W. Required
processing liquids are supplied to the three nozzles 41 by a
processing liquid supply mechanism 50 which will be described
later.
[0038] A liquid receiving cup 60 is installed inside the chamber 20
so as to surround the periphery of the chuck 31 of the substrate
holding/rotating part 30. The liquid receiving cup 60 collects the
processing liquids scattering from the rotating wafer W.
[0039] A liquid drain port 61 and an exhaust port 62 are installed
in the bottom of the liquid receiving cup 60. The processing liquid
captured by the liquid receiving cup 60 flows outward of the
processing unit 16 through the liquid drain port 61. The captured
processing liquid is collected, and reused or discarded in a
factory liquid drain system. The atmosphere of an internal space of
the liquid receiving cup 60 is discharged to a factory exhaust
system kept in a depressurized atmosphere through the exhaust port
62 and an exhaust conduit 63. An ejector (not shown) for promoting
the exhaust and a valve (for example, a butterfly valve) for
controlling an exhaust flow rate may be installed in the exhaust
conduit 63.
[0040] The internal structure of the liquid receiving cup 60 is
illustrated in FIG. 2 in a significantly simplified manner. The
liquid receiving cup 60 may be configured to allow different kinds
of processing liquids (for example, acidic liquid chemical,
alkaline liquid chemical, and organic liquid chemical) to flow
through the interior of the liquid receiving cup 60 via different
paths, and to be discharged outward of the processing unit 16
through exhaust ports 62 and exhaust conduits 63 which are
different from each other. The processing liquids can be switched
through the different paths. This configuration is well known in
the technical field of a semiconductor manufacturing apparatus, and
therefore, a description thereof will be omitted.
[0041] A ceiling plate (top plate) 70 capable of closing an upper
opening 65 of the liquid receiving cup 60 is installed inside the
chamber 20. The ceiling plate 70 can be moved up and down by an
elevating mechanism 71 between a processing position (a position
illustrated in FIG. 2) and a retracted position (not shown) above
the processing position. The ceiling plate 70 located at the
processing position is brought into contact with a peripheral
region of the upper opening 65 in the upper surface of the liquid
receiving cup 60 so as to close the upper opening 65 of the liquid
receiving cup 60. A seal member (not shown) may be installed to
seal a gap between the ceiling plate 70 and the liquid receiving
cup 60.
[0042] When the ceiling plate 70 is raised and retracted to the
retracted position, the chuck 31 is raised so that the wafer W can
be located above an upper end of the liquid receiving cup 60. In
this state, the arm of the substrate transfer device 17 illustrated
in FIG. 1 can enter the chamber 20 through a substrate
loading/unloading port 22 to transfer the wafer W to and out of the
chuck 31. When the ceiling plate 70 is moved up and down, the
nozzle holder 42 and the nozzle arm 43 are rotated by the arm
driving mechanism 44 and retracted from the position above the
ceiling plate 70.
[0043] A through-hole 72 is formed in the center of the ceiling
plate 70. By moving the nozzle holder 42 up and down by the arm
driving mechanism 44, the nozzle holder 42 can be inserted into the
through-hole 72 of the ceiling plate 70 located at the processing
position, and can be removed from the through-hole 72. When the
nozzle holder 42 is inserted into the through-hole 72, the nozzle
holder 42 closes the through-hole 72. A seal member (not shown) may
be installed to seal a gap between the nozzle holder 42 and the
ceiling plate 70.
[0044] A gas nozzle 73 for supplying an inert gas (here, a nitrogen
gas) to a space S (processing space) between a lower surface of the
ceiling plate 70 located at the processing position and an upper
surface of the wafer W held by the chuck 31 is installed in the
center of the ceiling plate 70. The gas nozzle 73 may be installed
at a position different from the illustrated position as long as
the gas nozzle 73 can supply the inert gas to the space S.
[0045] Next, the three nozzles 41, the nozzle holder 42, and the
processing liquid supply mechanism 50 will be described with
reference to FIG. 3. Hereinafter, reference symbol "N1" is affixed
to a first nozzle, reference symbol "N2" is affixed to a second
nozzle, and reference symbol "N3" is affixed to a third nozzle,
among the three nozzles 41, so as to distinguish them from one
another.
[0046] A DHF supply part 51A and a DIW supply part 51B are
connected to the first nozzle N1. Either a dilute hydrofluoric acid
(DHF) or a pure water (DIW) may be discharged from the first nozzle
N1 at a controlled flow rate. An SC1 supply part 52A, a citric acid
supply part 52B, and a DIW supply part 52C are connected to the
second nozzle N2. Either one of SC1, citric acid, and DIW may be
discharged as the processing liquid from the second nozzle N2 at a
controlled flow rate. An IPA supply part 53A is connected to the
third nozzle N3. Isopropyl alcohol (IPA) may be discharged from the
third nozzle N3 at a controlled flow rate.
[0047] In the respective supply parts 51A, 51B, 52A, 52B, 52C, and
53A, elements indicated by double circles in FIG. 3 represent
sources (for example, factory power, tank, and the like) of the
respective liquids. Elements indicated by white squares with "X"
written therein in FIG. 3 represent flow control devices. Examples
of the flow control devices include an opening/closing valve, a
flowmeter, a flow control valve, and the like. Other reference
numerals described in FIG. 3 will be described later.
[0048] Next, the processing of the wafer W performed in the
processing unit 16 will be described. The arm of the substrate
transfer device 17 which holds an unprocessed wafer W enters the
processing unit 16 through the substrate loading/unloading opening
22. At this time, the nozzles 41 are at the retracted position, the
ceiling plate 70 is also at the retracted position, and the chuck
31 of the substrate holding/rotating part 30 is raised to a
delivery position. The arm of the substrate transfer device 17
delivers the wafer W to the chuck 31 and is retracted from the
processing unit 16. Subsequently, the ceiling plate 70 is lowered
to the processing position (the position illustrated in FIG. 2) to
close the upper opening 65 of the liquid receiving cup 60.
Subsequently, the nozzles 41 move to the processing position (the
position illustrated in FIG. 2), and accordingly, the nozzle holder
42 closes the through-hole 72 of the ceiling plate 70. Thus, the
internal space of the liquid receiving cup 60 is substantially
sealed.
[0049] Subsequently, the nitrogen gas is discharged from the gas
nozzle 73. The internal space of the liquid receiving cup 60 is
always sucked through the exhaust port 62. Therefore, the air
inside the liquid receiving cup 60 is substituted with the nitrogen
gas so that the internal space of the liquid receiving cup 60
becomes a nitrogen gas atmosphere. Subsequently, the wafer W is
rotated by the substrate holding/rotating part 30. The rotation of
the wafer W is continuously performed until the processing of one
sheet of wafer W is completed. By rotating the wafer W in this way,
the nitrogen gas supplied to the region above the center of the
wafer W in the space S uniformly flows toward above the periphery
of the wafer W.
[0050] Thereafter, various processing liquids are supplied to the
wafer W. The supply of the processing liquids will be described
with reference to a time chart illustrated in FIG. 7. The first to
third nozzles N1, N2, and N3 discharge the processing liquids
toward or near the center WC (rotational center) of the wafer W
(details thereof will be described later). DHF, SC1, and citric
acid are cleaning liquid chemicals for removing a removal target
existing on a front surface WS of the wafer W. DIW is supplied as a
rinse liquid for removing, from the front surface WS of the wafer
W, the liquid chemical (DHF, SC1, or citric acid) which has been
supplied directly before the supply of DIW, the byproduct generated
by reaction with the respective liquid chemical, or the like. IPA
substitutes DIW existing on the front surface WS of the wafer W.
IPA, which is an organic solvent having higher volatility and lower
surface tension than DIW, serves to promote drying (uniform and
rapid drying) and suppress pattern collapse. When the processing
liquid supplied from one nozzle (N1 or N2) is switched from a first
processing liquid (e.g., DHF) to a second processing liquid (e.g.,
DIW), the first processing liquid and the second processing liquid
are continuously supplied in a substantially seamless manner.
[0051] First, the discharge of DHF is started from the first nozzle
N1 at time T1. At time T2, the processing liquid discharged from
the first nozzle N1 is switched from DHF to DIW. The discharge of
DIW from the first nozzle N1 is ended at time T5.
[0052] At time T3 before time T5, the discharge of DIW from the
second nozzle N2 is started. At time T4 after time T3 and before
time T5, the processing liquid discharged from the second nozzle N2
is switched from DIW to SC1.
[0053] Furthermore, the processing liquid (DIW discharged for times
T8 to T10) last discharged from the nozzle N2 remains in the second
nozzle N2 and a pipe connected thereto. Thus, the processing liquid
discharged from the second nozzle N2 immediately after time T3 as
indicated in the time chart is DIW. However, in a case where a
drain mechanism for a residual processing liquid (which is well
known) is installed in the second nozzle N2 and a pipe connected to
the second nozzle N2, SC1 may be discharged from the second nozzle
N2 immediately after time T3.
[0054] At time T6, the processing liquid discharged from the second
nozzle N2 is switched from SC1 to DIW. At time T7, the processing
liquid discharged from the second nozzle N2 is switched from DIW to
the citric acid. At time T8, the processing liquid discharged from
the second nozzle N2 is switched from the citric acid to DIW. The
discharge of DIW from the second nozzle N2 is ended at time
T10.
[0055] At time T9 before time T10, the discharge of DIW from the
first nozzle N1 is started. The discharge of DIW from the first
nozzle N1 is ended at time T12. At time T11 before time T12, the
discharge of IPA from the third nozzle N3 is started. The discharge
of IPA from the third nozzle N3 is ended at time T13.
[0056] After time T13, the discharge of the processing liquids from
all the nozzles N1, N2, and N3 is stopped and the rotation of the
wafer W is continued (specifically, the rotation speed of the wafer
W may be increased) so that the wafer W is dried. When the drying
of the wafer W is completed, the rotation of the wafer W is
stopped. Thereafter, the wafer W is unloaded from the processing
unit 16 in a reverse order of loading the wafer W. Thus, a series
of processes for one sheet of wafer W is completed.
[0057] As can be seen from the time chart illustrated in FIG. 7,
during a period OL1 from time T3 to time T5, during a period OL2
from time T9 to time T10, and during a period OL3 from time T11 to
time T12, two nozzles (N1 and N2, or N1 and N3) simultaneously
discharge the processing liquids. The periods OL1, OL2, and OL3 are
referred to as "overlapped periods". If the processing liquids
simultaneously discharged from the two nozzles are not in an
appropriate relationship, a problem such as liquid splash or
non-uniformity of the liquid film formed on the front surface WS of
the wafer W may occur. This will be described below.
[0058] Various terms defining the arrangement of the respective
nozzles 41 (N1, N2, and N3) and the direction of the processing
liquids discharged from the nozzles N1, N2, and N3 will be
described with reference to FIGS. 3 to 6.
[0059] Axis lines of the nozzles N1, N2, and N3 (specifically, axis
lines of discharge flow paths near the discharge port) are
indicated by A1, A2, and A3, respectively. Liquid columns formed by
the processing liquids discharged from the nozzles N1, N2, and N3
are indicated by P1, P2, and P3, respectively. In addition, since
gravity acts on the processing liquids discharged from the nozzles
N1, N2, and N3, the processing liquids discharged from the inclined
nozzles (N2 and N3 in the illustrated example) draw a parabola.
However, it is assumed herein that the processing liquids are
discharged from the nozzles N1, N2 and N3 with a sufficiently small
(e.g., about 20 to 30 mm) distance between the nozzles N1, N2, and
N3 and the front surface WS of the wafer W and at a sufficiently
large flow rate (liquid force), and thus, the gravity acting on the
processing liquids may be ignored. Therefore, it may be regarded
that the axis lines of the discharge ports of the nozzles N1, N2,
and N3 and the central axis lines of the liquid columns P1, P2, and
P3 coincide with each other.
[0060] FIGS. 4, 5 and 6 illustrate a state in which the respective
nozzles N1, N2 and N3 independently discharge the processing
liquids. Cut surfaces (circular or elliptical) obtained by cutting
the liquid columns P1, P2, and P3 of the processing liquids
discharged from the respective nozzles N1, N2, and N3 along the
plane of the front surface WS of the wafer W are indicated by
reference symbols B1, B2, and B3, respectively. Furthermore, the
centers of the cut surfaces B1, B2, and B3 are indicated by
reference symbols C1, C2, and C3, respectively. The centers C1, C2,
and C3 are also intersection points of the axis lines A1, A2, and
A3, and the front surface WS.
[0061] FIG. 8 is a schematic diagram illustrating the related art.
The processing liquids are discharged in a direction perpendicular
to the front surface WS near the center (rotational center) of the
front surface WS of the rotating wafer W from the two nozzles N1
and N2 (see the liquid columns P1 and P2). In addition, positions
of the discharged processing liquids deposited on the front surface
WS of the wafer W are separated from each other. In this case,
liquids, which are trying to spread mainly by virtue of a
centrifugal force after being deposited on the front surface WS,
collide with each other, so that a liquid film is largely swollen
near the collision portion. Furthermore, minute droplets are
scattered near the collision portion (occurrence of liquid
splash).
[0062] The scattered droplets may adhere to surfaces of constituent
members of the processing unit 16 (the outer surface of the liquid
receiving cup and the lower surface of the ceiling plate). A
particle-causing substance may be formed by drying the adhered
droplets or allowing droplets of different kinds of processing
liquids to react with each other to form the reaction product. In
particular, when the lower surface of the ceiling plate 70 is close
to the upper surface of the wafer W as in the processing unit 16
illustrated in FIG. 2, especially contamination of the lower
surface of the ceiling plate 70 may be problematic.
[0063] Furthermore, the swell of the liquid film generated near the
collision portion, namely non-uniformity of liquid film thickness,
causes thickness non-uniformity of the liquid film formed on the
front surface WS of the wafer W by the processing liquids. The
in-plane uniformity of processing may be impaired due to the
non-uniformity of the liquid film thickness.
[0064] In the present embodiment, when the two nozzles (N1 and N2,
or N1 and N3) simultaneously discharge the processing liquids, the
three nozzles N1, N2, and N3 are arranged so as not to cause the
aforementioned problem. Specifically, for example, as illustrated
in FIG. 3, the three nozzles N1, N2, and N3 are arranged to have a
positional relationship such that the axis lines A1, A2, and A3
intersect with each other at the center (rotational center) WC of
the front surface WS of the wafer W. An angle .theta.12 formed by
the axis line A1 and the axis line A2 is 30 degrees or less (20
degrees in the illustrated example), and an angle .theta.13 formed
by the axis line A1 and the axis line A3 is also 30 degrees or less
(20 degrees in the illustrated example). Furthermore, as indicated
in the time chart of FIG. 7, since the nozzles N2 and N3 do not
simultaneously discharge the processing liquids, the positional
relationship between the nozzles N2 and N3 does not matter in the
present embodiment.
[0065] According to the embodiment illustrated in FIG. 3, it is
possible to prevent or at least significantly suppress the problem
of liquid splash and non-uniformity of the liquid film
thickness.
[0066] In addition, there is an allowable range in the positional
relationship between the liquid columns of the processing liquids
discharged from the nozzles which simultaneously supply the
processing liquids. Hereinafter, this will be described with
reference to FIGS. 9 to 15 by taking the first liquid column P1 and
the second liquid column P2 as an example. Furthermore, it has been
found that the allowable range is described by a correlation
between the shape and arrangement of the first liquid column P1
when the processing liquid is discharged only from the first nozzle
N1, and the shape and arrangement of the second liquid column P2
when the processing liquid is discharged only from the second
nozzle N2. In FIGS. 9 to 15, upper diagrams show the liquid columns
P1 and P2 as viewed from the direction of a rotational axis line WA
(i.e., the vertical axis line) of the wafer W (from directly
above), and lower diagrams show the liquid columns P1 and P2 as
viewed from the side. Specifically, the lower diagrams show the
ones as viewed from the normal direction of the plane including the
first central axis line A1 which is the central axis line of the
first liquid column P1 and the second central axis line A2 which is
the central axis line of the second liquid column P2.
[0067] First, mainly from the viewpoint of preventing the liquid
splash, it is necessary to at least partially merge at least two
liquid columns P1 and P2 prior to depositing on the front surface
WS of the wafer W. This requires that at least one (here, the
second central axis line A2) of the first central axis line A1
which is the central axis line of the first liquid column P1 and
the second central axis line A2 which is the central axis line of
the second liquid column P2 should be inclined with respect to the
rotational axis line WA of the wafer W (condition 1), and that a
first cut surface B1 and a second cut surface B2 obtained by
cutting the first liquid column P1 and the second liquid column P2
along a horizontal plane including the front surface WS of the
wafer W should at least partially overlap each other as viewed in
the direction of the rotational axis line WA (condition 2).
[0068] The example of FIG. 8 does not satisfy the conditions 1 and
2, and in this case, the aforementioned problem occurs. Since
liquid splash occurs due to the collision between the processing
liquids once independently deposited on the front surface WS of the
wafer W, it is possible to prevent or at least significantly
suppress the liquid splash by satisfying the conditions 1 and
2.
[0069] Furthermore, mainly from the viewpoint of preventing
non-uniformity of the liquid film thickness, it is required that
any point on the first central axis line A1 (i.e., all points on
the first central axis line A1) be located on the second central
axis line A2, as viewed in the direction of the rotational axis
line WA of the wafer W (condition 3).
[0070] Hereinafter, the condition 3 will be described with
reference to FIGS. 9, 10, and 11 illustrating examples in which the
condition 3 is not satisfied. The second central axis line A2 is
inclined with respect to the rotational axis line WA of the wafer W
under the aforementioned condition 1. Therefore, the second central
axis line A2 is a straight line as viewed in the direction of the
rotational axis line WA. When the first central axis line A1 is
parallel to the rotational axis line WA, the first central axis
line A1 appears as a single point as viewed in the direction of the
rotational axis line WA (see the upper diagram of FIG. 9). That is,
in this case, the condition 3 means that the single point (the
first central axis line A1) described above is located on the
straight line (the second central axis line A2) described above as
viewed in the direction of the rotational axis line WA. The example
of FIG. 9 clearly does not satisfy the condition 3.
[0071] Furthermore, when both the first central axis line A1 and
the second central axis line A2 are inclined with respect to the
rotational axis line WA, both the first central axis line A1 and
the second central axis line A2 appear as straight lines as viewed
in the direction of the rotational axis line WA (see the upper
diagrams of FIGS. 10 and 11). That is, in this case, the condition
3 means that the two straight lines are located on the same
straight line. It is needless to say that the term "straight line"
used herein has an infinite length, and is different from "line
segment" and "half line".
[0072] In the example of FIG. 10, the two straight lines intersect
with each other only at one point as viewed in the direction of the
rotational axis line WA. This arrangement does not correspond to
"the "any point" on the first central axis line A1 is located on
the second central axis line A2 as viewed in the direction of the
rotational axis line WA of the wafer W". In the example of FIG. 11,
the two straight lines are parallel to each other and do not
intersect with each other.
[0073] As illustrated on the upper diagrams of FIGS. 10 and 11,
horizontal components V1 and V2 of velocity vectors of the
processing liquids forming the liquid columns P1 and P2 are not on
the same straight line and are directed in different directions as
viewed in the direction of the rotational axis line WA. In this
case, when the liquid columns P1 and P2 are merged to each other, a
vortex is formed. This vortex remains even when the processing
liquid spreads toward the peripheral edge of the front surface WS
while forming the liquid film after it is deposited on the front
surface WS of the wafer W, thus forming a film thickness
distribution having a non-uniform vortex shape on the front surface
WS of the wafer W. Under such circumstances, the in-plane
uniformity of the processing result may be deteriorated. The
example of FIG. 9 also has the same problem, but the degree is
lighter than those in the cases of FIGS. 10 and 11. By satisfying
the aforementioned condition 3, it is possible to prevent or
suppress the aforementioned problems and to improve the in-plane
uniformity of the processing result. The condition 3 has little
influence on the presence or absence of liquid splash.
[0074] Furthermore, examples of FIGS. 12 to 15 as described
hereinbelow satisfy the condition 3.
[0075] In addition to the aforementioned condition 3, even if the
horizontal components V1 and V2 of the velocity vectors are on the
same straight line as viewed in the direction of the rotational
axis line WA, it is preferable that they not be directed in the
same direction (condition 3a). When they are directed in the same
direction, a cross-sectional shape of the merged liquid on the
front surface WS of the wafer W becomes elliptical with a large
flatness having a long axis in the lateral direction in the figure.
Then, the processing liquid does not spread uniformly on the front
surface WS of the wafer W, causing unevenness of the liquid film.
Accordingly, when both the first central axis line A1 and the
second central axis line A2 are inclined with respect to the
rotational axis line WA, as illustrated in FIG. 12, it is
preferable that the horizontal components V1 and V2 are directed in
different directions as viewed in the direction of the rotational
axis line WA. One of the first central axis line A1 and the second
central axis line A2 may be parallel to the rotational axis line
WA.
[0076] Hereinafter, other conditions, which may be adopted from the
viewpoint of preventing or suppressing liquid splash and
non-uniformity of liquid film thickness distribution, will be
described with reference to FIGS. 12 to 15.
[0077] An angle .theta.12 formed by the first central axis line A1
and the second central axis line A2 may be 30 degrees or less
(condition 4). When the first central axis line A1 is parallel to
the rotational axis line WA of the wafer W (see FIGS. 13 to 15) or
inclined in the same direction as the second central axis line A2
(not shown), if the angle .theta.12 exceeds 30 degrees, the
cross-sectional shape of the merged liquid on the front surface WS
of the wafer W becomes elliptical with a large flatness having a
long axis in the lateral direction in FIGS. 12 to 15. Then, the
processing liquid does not spread uniformly on the front surface WS
of the wafer W, causing non-uniformity of the liquid film
thickness. Specifically, for example, a fylfot-shaped vortex
pattern as illustrated in FIG. 16 is generated, thus resulting in
non-uniformity of the liquid film thickness in which the liquid
film thickness is large in this portion and the liquid film
thickness is small in other portions. Under such circumstances, the
in-plane uniformity of the processing result may be
deteriorated.
[0078] Furthermore, for example, as illustrated in FIG. 12, when
the first central axis line A1 is inclined in a direction opposite
to the second central axis line A2, if the angle .theta.12 is
larger than 30 degrees, the processing liquids may collide
violently. This may cause liquid splash or non-uniformity of the
liquid film thickness. Therefore, even in this case, it is
preferable that the condition 4 is satisfied.
[0079] Moreover, in addition to the aforementioned condition 4,
both an angle .theta.W1 (see FIG. 12 for the definition) formed by
the rotational axis line WA and the first central axis line A1 and
an angle .theta.W2 (see FIG. 12 for the definition) formed by the
rotational axis line WA and the second central axis line A2 may be
30 degrees or less (condition 4a). If the angles .theta.W1 and
.theta.W2 are increased, even when the first liquid column P1 alone
or the second liquid column P2 alone is deposited on the front
surface of the wafer W, the aforementioned cut surfaces B1 and B2
become elliptical that is largely flat. This is because the
non-uniformity of the liquid film thickness is likely to occur.
[0080] Furthermore, in addition to the aforementioned condition 2,
for example, as illustrated in FIGS. 12 to 15, it is preferable
that the center C1 of the cut surface B1 is in the cut surface B2,
and the center C2 of the cut surface B2 is in the cut surface B1
(condition 2a). That is, it is preferable that an overlapping value
between the cut surface B1 and the cut surface B2 is sufficiently
large, in other words, a distance D12 between the center C1 and the
center C2 is sufficiently small. By doing so, it is possible to
more reliably prevent liquid splash. Furthermore, it is possible to
suppress disturbance of the flow of the processing liquid after
merging, which may occur when the overlapping value between the cut
surface B1 and the cut surface B2 is small, and to improve the
thickness uniformity of the liquid film formed on the front surface
WS of the wafer W.
[0081] In FIGS. 13 and 15, a two-digit number "12" given to the
uppercase alphabet indicates a position or distance determined
based on a relative positional relationship between the nozzle N
"1" and the nozzle N "2". E12 is an intersection point of the axis
line A1 with the axis line A2. H12 is a distance (vertical
distance) from the front surface WS of the wafer W to the
intersection point E12. When the intersection point E12 is at a
position lower than the front surface WS, H12 takes a negative
value, and when the intersection point E12 is at a position higher
than the front surface WS, H12 takes a positive value. C1 is an
intersection point of the axis line A1 with the front surface WS of
the wafer W. C2 is an intersection point of the axis line A2 with
the front surface WS of the wafer W. D12 is a distance (horizontal
distance) between the intersection point C1 and the intersection
point C2. In the example of FIG. 13, both the distance H12 and the
distance D12 are negative values. In the example of FIG. 14, both
the distance H12 and the distance D12 (not shown because they are
both zero) are zero. In the example of FIG. 15, both the distance
H12 and the distance D12 have positive values.
[0082] The distance D12 between the center C1 and the center C2 may
fall within a range of -2 mm to +2 mm, specifically a range of -1
mm to +1 mm, more specifically 0 mm (i.e., the center C1 and the
center C2 coincide with each other) (see FIGS. 3 and 14))
(condition 2b). By doing so, it is possible to more reliably
prevent liquid splash and to suppress disturbance of the flow of
the processing liquid after merging. Furthermore, a preferable
maximum value of the distance D12 depends on the diameters of the
liquid column P1 and the liquid column P2. When the diameters of
the liquid column P1 and the liquid column P2 are, e.g., about 4.3
to 4.4 mm, if the distance D12 is 2 mm or less, it has been
confirmed that good results are obtained.
[0083] The distance H12 may fall within a range of -3 mm to +3 mm,
specifically a range of -2 mm to +2 mm, more specifically 0 mm
(i.e., the center C1 and the center C2 coincide with each other)
(see FIG. 3 and FIG. 14) (condition 5). Furthermore, H12 is a value
uniquely determined according to .theta.12 and D12 described
above.
[0084] When the distance H12 takes a large positive value, the
cross-sectional shape of the merged liquid on the front surface WS
of the wafer W becomes elliptical that is largely flay having a
long axis in the lateral direction in FIG. 11. As a result, the
processing liquid does not spread uniformly on the front surface WS
of the wafer W, causing unevenness of liquid film. Specifically,
for example, a fylfot-shaped vortex pattern as illustrated in FIG.
16 is generated, resulting in the non-uniformity of liquid film
thickness in which the liquid film thickness is large in this
portion and the liquid film thickness is small in other portions.
Under such circumstances, the in-plane uniformity of the processing
result may be deteriorated. By satisfying the condition 5, it is
possible to prevent occurrence of such an event and to improve the
in-plane uniformity of the processing result. The condition 5 has
little influence on the presence or absence of liquid splash.
[0085] On the other hand, when the absolute value of the distance
H12 is a large negative value, the same problem occurs as when the
distance D12 is increased.
[0086] A specific example of the arrangement of the nozzles and
various process conditions used in actual operation will be
described with reference to FIG. 3. In this specific example, the
three nozzles N1, N2, and N3 are arranged to have a positional
relationship such that the first axis line A1, the second axis line
A2, and the third axis line A3 intersect with each other at the
center (rotational center) WC of the front surface WS of the wafer
W. The first axis line A1 extends in the vertical direction, namely
parallel to the rotational axis line WA of the wafer W. The angle
.theta.12 formed by the first axis line A1 and the second axis line
A2 is 20 degrees, and the angle .theta.13 formed by the first axis
line A1 and the third axis line A3 is also 20 degrees. The
diameters of the nozzles N1 and N2 are both 6.4 mm, and the
diameter of the nozzle N3 is 3.2 mm. Accordingly, the diameter of
the first liquid column P1 and the diameter of the second liquid
column P2 are substantially the same, and the diameter of the third
liquid column P3 is smaller than the diameters of the first liquid
column P1 and the second liquid column P2. The flow rates of DHF
and DIW discharged from the nozzle N1 are both in the range of
1,000 to 1,500 mL/min. The flow rates of SC1, citric acid and DIW
discharged from the nozzle N2 are all in the range of 1,000 to
1,500 mL/min. The flow rate of IPA discharged from the nozzle N3 is
in the range of 75 to 350 mL/min. The revolution per minute of the
wafer W is 1,000 to 1,500 rpm. Under the aforementioned conditions,
even when the processing liquids are simultaneously discharged from
the nozzles N1 and N2 and the processing liquids are simultaneously
discharged from the nozzles N1 and N3, it has been confirmed that
the occurrence of liquid splash and non-uniformity of liquid film
which are problematic do not occur.
[0087] DHF, which is likely to have a problem of coverage
characteristics (surface coverage characteristics of liquid film)
when supplied to the wafer W alone, is preferably discharged from
the nozzle N1 (because the first axis line A1 extends in the
vertical direction) which enables the most uniform liquid film
formation. SC1, citric acid, and IPA do not have a problem of
coverage characteristics even when they are discharged from any
nozzle. In consideration of this, the kinds of the processing
liquids to be discharged from the nozzles N1, N2, and N3 are
determined.
[0088] Furthermore, the nozzles (N1, N2, and N3) which discharge
the processing liquids at the maximum flow rate may not be nozzles
whose axis lines (A1, A2, and A3) are oriented in the vertical
direction. Even if the nozzle whose axis line is inclined
discharges the processing liquid at a larger flow rate than that of
the nozzle whose axis line is oriented in the vertical direction,
the problem of liquid splash and liquid film non-uniformity does
not occur as long as the aforementioned conditions are
satisfied.
[0089] According to the aforementioned embodiments, even if the
processing liquids are simultaneously discharged from the two
nozzles, there is no case where the problem of liquid splash and
film thickness non-uniformity occurs. Therefore, the members (e.g.,
the ceiling plate) near the wafer W are not contaminated by mist
generated by liquid splash. In addition, since a liquid film having
a uniform thickness is formed, liquid processing having high
in-plane uniformity can be performed.
[0090] In the aforementioned embodiments, the nozzles N1, N2, and
N3 supply the processing liquids in a state where they are
stationary above the center of the wafer W, but the present
disclosure is not limited thereto. For example, in a case where the
substrate processing apparatus has no ceiling plate, the substrate
processing apparatus may discharge the processing liquids while
moving (scanning) between a position above the center of the wafer
W and a position above the peripheral edge of the wafer W. Also, in
this case, when the processing liquids are simultaneously
discharged from the two nozzles, it is preferable that the nozzles
are kept stationary above the center of the wafer W.
[0091] In the aforementioned embodiments, the two nozzles N1 and N2
are held by the common nozzle holder and arm, but the present
disclosure is not limited thereto. The first nozzle N1 may be held
by a first nozzle holder and a first nozzle arm, and the second
nozzle N2 may be held by a second nozzle holder and a second nozzle
arm. In this case, when the processing liquids are simultaneously
discharged from the first nozzle N1 and the second nozzle N2, the
first nozzle N1 and the second nozzle N2 may be arranged to have
the same position relationship with the aforementioned embodiments
by moving each of the first and second nozzle arms.
[0092] In the aforementioned embodiments, the target substrate is a
semiconductor wafer, but the present disclosure is not limited
thereto. The substrate may be any type of substrate used in the
manufacture field of semiconductor device, such as a glass
substrate or a ceramic substrate.
[0093] According to the present disclosure in some embodiments, it
is possible to prevent or at least significantly suppress liquid
splash which is caused by mutual interference between a first
processing liquid and a second processing liquid and/or
non-uniformity of liquid film thickness of processing liquids
formed on a substrate when the first processing liquid and the
second processing liquid are simultaneously supplied onto the
substrate from different nozzles.
[0094] It should be noted that the embodiments disclosed herein are
exemplary in all respects and are not restrictive. The
above-described embodiments may be omitted, replaced or modified in
various forms without departing from the scope and spirit of the
appended claims.
* * * * *