U.S. patent application number 15/925327 was filed with the patent office on 2018-07-26 for substrate processing method.
The applicant listed for this patent is SCREEN Holdings Co., Ltd.. Invention is credited to Atsuyasu MIURA, Naoki SAWAZAKI.
Application Number | 20180207685 15/925327 |
Document ID | / |
Family ID | 56163142 |
Filed Date | 2018-07-26 |
United States Patent
Application |
20180207685 |
Kind Code |
A1 |
MIURA; Atsuyasu ; et
al. |
July 26, 2018 |
SUBSTRATE PROCESSING METHOD
Abstract
A substrate processing method includes a substrate holding step
of holding a substrate horizontally, a liquid droplet discharging
step wherein liquid droplets of an organic solvent, formed by
mixing the organic solvent and a gas, are discharged from a
double-fluid nozzle toward a predetermined discharge region within
an upper surface of the substrate, and a liquid film forming step,
executed before the liquid droplet discharging step, of supplying
the organic solvent to the double fluid nozzle without supplying
the gas, so as to discharge the organic solvent in a continuous
stream mode from the double-fluid nozzle to form a liquid film of
the organic solvent covering the discharge region on the upper
surface of the substrate.
Inventors: |
MIURA; Atsuyasu; (Kyoto,
JP) ; SAWAZAKI; Naoki; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCREEN Holdings Co., Ltd. |
Kyoto |
|
JP |
|
|
Family ID: |
56163142 |
Appl. No.: |
15/925327 |
Filed: |
March 19, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14978693 |
Dec 22, 2015 |
9956594 |
|
|
15925327 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/67051 20130101;
H01L 21/67028 20130101; H01L 21/02065 20130101 |
International
Class: |
B08B 3/02 20060101
B08B003/02; H01L 21/67 20060101 H01L021/67; B08B 3/08 20060101
B08B003/08; B08B 3/10 20060101 B08B003/10; H01L 21/02 20060101
H01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2014 |
JP |
2014-265537 |
Claims
1. A substrate processing method comprising: a substrate holding
step of holding a substrate horizontally; a liquid droplet
discharging step wherein liquid droplets of an organic solvent, the
liquid droplets being formed by mixing the organic solvent and a
gas, are discharged from a double-fluid nozzle toward a
predetermined discharge region within an upper surface of the
substrate, while a first guard faces a peripheral end surface of
the substrate; a liquid film forming step, executed before the
liquid droplet discharging step, of supplying the organic solvent
onto the upper surface of the substrate to form a liquid film of
the organic solvent covering the discharge region on the upper
surface of the substrate; a drying step of rotating the substrate
around the rotational axis, without supplying the organic solvent
to the upper surface of the substrate, to dry the upper surface of
the substrate; and a facing guard changing step of changing the
guard facing the peripheral end surface of the substrate from the
first guard to a second guard, differing from the first guard,
after the liquid droplet discharging step is ended and before the
drying step is executed.
2. The substrate processing method according to claim 1, further
comprising: a first rotating step of rotating the substrate around
the rotational axis in parallel with the liquid droplet discharging
step.
3. The substrate processing method according to claim 2, further
comprising: a post-supplying step of supplying the organic solvent
to the upper surface of the substrate after the liquid droplet
discharging step.
4. The substrate processing method according to claim 3, further
comprising: a second rotating step, executed in parallel with the
post-supplying step, of rotating the substrate around the
rotational axis at a higher speed than that in the first rotating
step.
5. The substrate processing method according to claim 3, wherein in
the post-supplying step, the organic solvent is supplied to the
double-fluid nozzle without supplying the gas, so as to discharge
the organic solvent in a continuous stream mode from the
double-fluid nozzle.
6. The substrate treatment method according to claim 1, further
comprising a nozzle moving step of moving the double fluid nozzle;
wherein the liquid droplet discharging step starts discharging of
droplets of the organic solvent to a discharge region of the
organic solvent on the upper surface of the substrate at the end of
the liquid film forming step.
7. The treatment method according to claim 6, wherein the discharge
region includes a peripheral edge on the upper surface of the
substrate; and the liquid droplet discharging step starts
discharging of droplets of the organic solvent to the peripheral
edge on the upper surface of the substrate.
8. The substrate processing method according to claim 1, further
comprising: a first preliminary preparation step of preparing a
silicon substrate, having SiO2 disposed at the upper surface, as
the substrate.
9. The substrate processing method according to claim 1, further
comprising: a second preliminary preparation step of preparing a
semiconductor substrate, including an insulating film constituted
of a low dielectric constant material of lower relative dielectric
constant than SiO2 and a copper wiring disposed on the insulating
film, as the substrate.
10. A substrate processing method comprising: a substrate holding
step of holding a substrate horizontally; a liquid droplet
discharging step wherein liquid droplets of an organic solvent, the
liquid droplets being formed by mixing the organic solvent and a
gas, are discharged from a double-fluid nozzle toward a
predetermined discharge region within an upper surface of the
substrate; a liquid film forming step, executed before the liquid
droplet discharging step, of supplying the organic solvent onto the
upper surface of the substrate to form a liquid film of the organic
solvent covering the discharge region on the upper surface of the
substrate; a discharge region moving step of moving the position of
the discharge region within the upper surface of the substrate; and
an additional organic solvent supplying step of supplying, in
parallel to the discharge region moving step, the organic solvent
to a rearward position with respect to a direction of progress of
the discharge region; and wherein the organic solvent is not
supplied to a forward position with respect to the direction of
progress of the discharge region in the additional organic solvent
supplying step.
11. The substrate processing method according to claim 10, further
comprising: a first rotating step of rotating the substrate around
the rotational axis in parallel with the liquid droplet discharging
step.
12. The substrate processing method according to claim 11, further
comprising: a post-supplying step of supplying the organic solvent
to the upper surface of the substrate after the liquid droplet
discharging step.
13. The substrate processing method according to claim 12, further
comprising: a second rotating step, executed in parallel with the
post-supplying step, of rotating the substrate around the
rotational axis at a higher speed than that in the first rotating
step.
14. The substrate processing method according to claim 12, wherein
in the post-supplying step, the organic solvent is supplied to the
double-fluid nozzle without supplying the gas, so as to discharge
the organic solvent in a continuous stream mode from the
double-fluid nozzle.
15. The substrate treatment method according to claim 10, further
comprising a nozzle moving step of moving the double fluid nozzle;
wherein the liquid droplet discharging step starts discharging of
droplets of the organic solvent to a discharge region of the
organic solvent on the upper surface of the substrate at the end of
the liquid film forming step.
16. The treatment method according to claim 15, wherein the
discharge region includes a peripheral edge on the upper surface of
the substrate; and the liquid droplet discharging step starts
discharging of droplets of the organic solvent to the peripheral
edge on the upper surface of the substrate.
17. The substrate processing method according to claim 10, further
comprising: a first preliminary preparation step of preparing a
silicon substrate, having SiO2 disposed at the upper surface, as
the substrate.
18. The substrate processing method according to claim 10, further
comprising: a second preliminary preparation step of preparing a
semiconductor substrate, including an insulating film constituted
of a low dielectric constant material of lower relative dielectric
constant than SiO2 and a copper wiring disposed on the insulating
film, as the substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/978,693, filed Dec. 22, 2015, which claims
the benefit of Japanese Patent Application No. 2014-265537, filed
Dec. 26, 2014, the contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a substrate processing
method for processing a substrate by using an organic solvent.
Examples of substrates to be processed include semiconductor
wafers, substrates for liquid crystal displays, substrates for
plasma displays, substrates for FEDs (Field Emission Displays),
substrates for optical disks, substrates for magnetic disks,
substrates for magneto-optical disks, substrates for photomasks,
ceramic substrates, substrates for solar cells, etc.
2. Description of Related Art
[0003] In a manufacturing process for a semiconductor device or a
liquid crystal display, a cleaning processing of supplying a
cleaning liquid to a major surface of substrate, such as a
semiconductor wafer or a glass substrate for liquid crystal display
panel, etc., to clean the major surface of the substrate with the
cleaning liquid is performed. For example, a substrate processing
apparatus of a single substrate processing type that processes a
substrate at a time includes a spin chuck that rotates the
substrate while holding the substrate substantially horizontally by
means of a plurality of chuck pins and a nozzle arranged to supply
a cleaning liquid to a major surface of the substrate rotated by
the spin chuck.
[0004] In the arrangement of U.S. Patent Application No.
2003/178047 A1, a spouting nozzle that spouts minute liquid
droplets of the cleaning liquid is used as the nozzle instead of a
straight nozzle that discharges a continuous stream. Also,
isopropyl alcohol (IPA) is used as the cleaning liquid. That is,
with the arrangement of U.S. Patent Application No. 2003/178047 A1,
minute liquid droplets of IPA that are spouted from the spouting
nozzle are supplied to the major surface of the substrate and the
major surface is cleaned thereby.
SUMMARY OF THE INVENTION
[0005] However, at the start of discharge of the organic solvent
(IPA) liquid droplets, a particle diameter distribution of the
organic solvent liquid droplets discharged from a double-fluid
nozzle (spouting nozzle) is in an unstable state. Therefore, when
the discharge of the organic solvent liquid droplets from the
double-fluid nozzle onto an upper surface (major surface) of the
substrate is started, the organic solvent liquid droplets in the
state of unstable particle diameter distribution collide directly
against the upper surface of the substrate that is in a dry state
and this may cause particles to form on the upper surface of the
substrate.
[0006] An object of the present invention is thus to provide a
substrate processing method by which a substrate can be processed
satisfactorily using liquid droplets of an organic solvent from a
double-fluid nozzle while suppressing formation of particles.
[0007] The present invention provides a substrate processing method
including a substrate holding step of holding a substrate
horizontally, a liquid droplet discharging step of making liquid
droplets of an organic solvent, formed by mixing the organic
solvent and a gas, be discharged from a double-fluid nozzle toward
a predetermined discharge region within an upper surface of the
substrate, and a liquid film forming step, executed before the
liquid droplet discharging step, of supplying the organic solvent
to the double fluid nozzle without supplying the gas to discharge
the organic solvent in a continuous stream mode from the
double-fluid nozzle to form a liquid film of the organic solvent
covering the discharge region.
[0008] With the present method, the organic solvent liquid droplets
are discharged from the double-fluid nozzle toward the discharge
region within the upper surface of the substrate. Foreign matter
(particles, etc.) attached to the discharge region are removed
physically by collision of the organic solvent liquid droplets
against the upper surface of the substrate. The upper surface of
the substrate can thereby be processed satisfactorily.
[0009] Also, the organic solvent liquid film that covers the
discharge region is formed on the upper surface of the substrate
before the discharge of the organic solvent liquid droplets.
Therefore, the organic solvent liquid droplets discharged from the
double-fluid nozzle collide against the organic solvent liquid film
covering the discharge region. The organic solvent liquid droplets
can thus be prevented from directly colliding against the upper
surface of the substrate in a dry state at the start of liquid
droplet discharge at which a particle diameter distribution of the
discharged organic solvent liquid droplets is unstable. Formation
of particles in accompaniment with the execution of the liquid
droplet discharging step can thus be suppressed.
[0010] Also, the organic solvent discharged from the double-fluid
nozzle can be switched from the continuous stream mode to a liquid
droplet mode by switching the supplying of the gas to the
double-fluid nozzle from a stopped state to a supplying state. The
organic solvent used in the liquid droplet discharging step and the
organic solvent used in the liquid film forming step are discharged
from a nozzle in common and therefore the liquid droplet
discharging step can be started without delay after stopping the
supplying of the organic solvent in the liquid film forming step.
That is, the organic solvent can be supplied without interruption
to the upper surface of the substrate. Drying of the upper surface
of the substrate during transition from the liquid film forming
step to the liquid droplet discharging step can thus be suppressed
and formation of particles can thus be suppressed effectively
during the transition from the liquid film forming step to the
liquid droplet discharging step.
[0011] By the above, the substrate can be processed satisfactorily
using the organic solvent liquid droplets from a double-fluid
nozzle while suppressing the formation of particles.
[0012] Also, the substrate processing method may further include a
first rotating step of rotating the substrate around the rotational
axis in parallel to the liquid droplet discharging step.
[0013] With the present method, the organic solvent liquid film is
formed on the upper surface of the substrate in the liquid droplet
discharging step. The substrate is rotated in parallel to the
liquid droplet discharging step and therefore the liquid film
formed on the upper surface of the substrate can be made thin. The
organic solvent liquid droplets can thus be made to arrive on the
upper surface of the substrate and foreign matter attached to the
upper surface of the substrate can thus be removed
satisfactorily.
[0014] Also, the substrate processing method may further include a
post-supplying step of supplying the organic solvent to the upper
surface of the substrate after the liquid droplet discharging
step.
[0015] With the present method, the organic solvent is supplied to
the upper surface of the substrate in the post-supplying step
performed after the liquid droplet discharging step. The foreign
matter removed from the substrate upper surface by the physical
cleaning in the liquid droplet discharging step can thus be rinsed
off by the organic solvent and reattachment of the foreign matter
onto the upper surface of the substrate can thereby be suppressed
or prevented.
[0016] Also, the substrate processing method may further include a
second rotating step, executed in parallel to the post-supplying
step, of rotating the substrate around the rotational axis at a
higher speed than that in the first rotating step.
[0017] With the present method, the rotation speed of the substrate
in the post-supplying step is higher than that in the first
rotating step and therefore a large centrifugal force acts on the
organic solvent supplied to the upper surface of the substrate. The
foreign matter removed from the substrate upper surface by the
physical cleaning can thereby be spun off from sides of the
substrate together with the organic solvent and remaining of the
foreign matter on the upper surface of the substrate can thus be
suppressed or prevented.
[0018] Also, with the substrate processing method, in the
post-supplying step, the organic solvent may be supplied to the
double-fluid nozzle without supplying the gas to discharge the
organic solvent in a continuous stream mode from the double-fluid
nozzle.
[0019] With the present method, the organic solvent discharged from
the double-fluid nozzle can be switched from the liquid droplet
mode to the continuous stream mode by switching the supplying of
the gas to the double-fluid nozzle from the supplying state to the
stopped state. The organic solvent used in the liquid droplet
discharging step and the organic solvent used in the post-supplying
step are discharged from a nozzle in common and therefore the
post-supplying step can be started without delay after stopping the
supplying of the organic solvent in the liquid droplet discharging
step. That is, the organic solvent can be supplied without
interruption to the upper surface of the substrate. Drying of the
upper surface of the substrate during transition from the liquid
droplet discharging step to the post-supplying step can thus be
suppressed and formation of particles can thus be suppressed
effectively during the transition from the liquid droplet
discharging step to the post-supplying step.
[0020] The substrate treatment method may further include a nozzle
moving step of moving the double fluid nozzle, and the liquid
droplet discharging step may start discharging of droplets of the
organic solvent to a landed position of the organic solvent on the
upper surface of the substrate at the end of the liquid film
forming step, as the discharge region.
[0021] In this case, the discharge region can be reliably covered
with the organic solvent liquid film at the start of discharge of
droplets of the organic solvent. Therefore, direct collision of
droplets of the organic solvent against the upper surface of the
substrate in the dry state can be reliably avoided at the start of
discharge of droplets of the organic solvent, even in case of
forming the liquid film while moving the double-fluid nozzle.
[0022] The landed position may include a peripheral edge on the
upper surface of the substrate, and the liquid droplet discharging
step starts discharging of droplets of the organic solvent to the
peripheral edge on the upper surface of the substrate, as the
discharge region.
[0023] Also, the liquid droplet discharging step may be a step that
is executed in a state where a first guard is made to face a
peripheral end surface of the substrate, and the substrate
processing method may further include a drying step of rotating the
substrate around the rotational axis, without supplying the organic
solvent to the upper surface of the substrate, to dry the upper
surface of the substrate and a facing guard changing step of
changing the guard facing the peripheral end surface of the
substrate from the first guard to a second guard, differing from
the first guard, after the liquid droplet discharging step is ended
and before the drying step is executed.
[0024] With the present method, in the liquid droplet discharging
step in which the upper surface of the substrate is physically
cleaned by the organic solvent liquid droplets, the organic solvent
expelled from the substrate may contain foreign matter removed from
the substrate. During the liquid droplet discharging step, the
first guard faces the peripheral end surface of the substrate and
the organic solvent that contains foreign matter may thus be
attached to the first guard.
[0025] However, during the drying step, the second guard is made to
face the peripheral end surface of the substrate instead of the
first guard that may have the foreign-matter-containing organic
solvent attached thereto. Therefore during the drying step, the
substrate after the cleaning processing can be suppressed
effectively from being contaminated by the organic solvent
(foreign-matter-containing organic solvent) attached to the guard
facing the peripheral end surface of the substrate.
[0026] Also, the substrate processing method may further include a
discharge region moving step of moving the position of the
discharge region within the upper surface of the substrate and an
additional organic solvent supplying step of supplying, in parallel
to the discharge region moving step, the organic solvent to a
rearward position with respect to a direction of progress of the
discharge region. In this case, the organic solvent does not have
to be supplied to a forward position with respect to the direction
of progress of the discharge region in the additional organic
solvent supplying step.
[0027] With the present method, regardless of where in the upper
surface of the substrate the position of the discharge region is
disposed, the organic solvent is supplied separately to a vicinity
of the position of the discharge region. Although if the upper
surface of the substrate dries during the liquid droplet
discharging step, particles may form in the dried region, with the
present method, the organic solvent is supplied to the vicinity of
the position of the discharge region and therefore drying of the
upper surface of the substrate during the liquid droplet
discharging step can be prevented.
[0028] If, for instance, the organic solvent is supplied to a
forward position with respect to the direction of progress of the
discharge region of the organic solvent liquid droplets from the
double-fluid nozzle, the organic solvent liquid film at the
discharge region becomes thick. If the liquid film that covers the
discharge region is thick, the organic solvent may splash in
accompaniment with the discharge of the organic solvent liquid
droplets onto the discharge region. Contaminants contained in the
organic solvent may scatter to the periphery due to the splashing
of the organic solvent and may cause particle formation.
[0029] With the present method, the organic solvent is supplied
only to the rearward position with respect to the direction of
progress of the discharge region and therefore the organic solvent
liquid film at the discharge region can be kept thin while
preventing the drying of the upper surface of the substrate.
Splashing of the organic solvent discharged onto the discharge
region can thus be suppressed. Formation of particles in
accompaniment with the execution of the liquid droplet discharging
step can thereby be suppressed more effectively.
[0030] Also, the substrate processing method may further include a
first preliminary preparation step of preparing a silicon
substrate, having SiO.sub.2 disposed at the upper surface, as the
substrate.
[0031] With the present method, the organic solvent is low in
etching power with respect to SiO.sub.2. Therefore, a surface of
the silicon substrate can be cleaned satisfactorily without
excessively etching the SiO.sub.2 disposed at the upper surface of
the substrate.
[0032] Also, the substrate processing method may further include a
second preliminary preparation step of preparing a semiconductor
substrate, including an insulating film constituted of a low
dielectric constant material of lower relative dielectric constant
than SiO.sub.2 and a copper wiring disposed on the insulating film,
as the substrate.
[0033] With the present method, the organic solvent is used as the
cleaning liquid to clean the upper surface of the substrate. The
organic solvent is low in oxidizing power with respect to copper.
The upper surface of the semiconductor substrate can thus be
cleaned satisfactorily without excessively etching the copper
wiring.
[0034] In this case, the organic solvent may have a low surface
tension. A low dielectric constant material has a high contact
angle and therefore a surface of the insulating film exhibits high
hydrophobicity (lyophobicity). However, the surface of the
insulating film having high hydrophobicity can be wetted
satisfactorily by using an organic solvent, having a low surface
tension, as the cleaning liquid. A liquid film of the organic
solvent that covers an entirety of the upper surface of the
semiconductor substrate can thereby be formed satisfactorily.
[0035] The above and yet other objects, features, and effects of
the present invention shall be made clear by the following
description of the preferred embodiments in reference to the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a diagram of a substrate processing apparatus
which executes a substrate processing method according to a first
preferred embodiment of the present invention as viewed from a
horizontal direction.
[0037] FIG. 2A is an illustrative sectional view of the arrangement
of a double-fluid nozzle included in the substrate processing
apparatus.
[0038] FIG. 2B is a block diagram for explaining the electrical
structure of the substrate treatment apparatus shown in FIG. 1.
[0039] FIG. 3 is an enlarged sectional view of a vicinity of a
front surface of a substrate to be processed by the substrate
processing apparatus.
[0040] FIGS. 4A to 4C are illustrative sectional views showing a
method for manufacturing the substrate shown in FIG. 3 in order of
process.
[0041] FIG. 5 is a flowchart for describing a processing example of
a cleaning processing performed by the substrate processing
apparatus.
[0042] FIGS. 6A and 6B are illustrative diagrams for describing the
processing example of the cleaning processing.
[0043] FIGS. 6C and 6D are schematic diagrams for describing
processes following that of FIG. 6B.
[0044] FIG. 6E is a schematic diagram for describing a process
following that of FIG. 6D.
[0045] FIGS. 7A and 7B are diagrams of test results of a first
cleaning test performed with an example.
[0046] FIG. 8 is a diagram of a test result of the first cleaning
test performed with a comparative example.
[0047] FIG. 9 is a schematic plan view for describing a particle
mode.
[0048] FIG. 10 is a diagram of test results of a second cleaning
test.
[0049] FIG. 11 is an illustrative diagram of a portion of a
substrate processing apparatus which executes a substrate
processing method according to a second preferred embodiment of the
present invention.
[0050] FIGS. 12A and 12B are illustrative diagrams for describing a
processing example of a cleaning processing according to the second
preferred embodiment of the present invention.
[0051] FIG. 13 is an enlarged sectional view of a vicinity of a
front surface of another substrate to be processed.
[0052] FIGS. 14A to 14C are illustrative sectional views showing a
method for manufacturing the substrate shown in FIG. 13 in order of
process.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0053] FIG. 1 is a diagram of a substrate processing apparatus 1
which executes a substrate processing method according to a first
preferred embodiment of the present invention as viewed from a
horizontal direction. FIG. 2A is an illustrative sectional view of
the arrangement of a double-fluid nozzle 16 included in the
substrate processing apparatus 1.
[0054] The substrate processing apparatus 1 is a single substrate
processing type apparatus arranged to perform a cleaning processing
on a major surface (upper surface) at a device formation region
side of a substrate W, such as a silicon substrate 61 (see FIG. 3).
The substrate processing apparatus 1 includes a box-shaped
processing chamber 2 having an internal space, a spin chuck
(substrate holding unit) 3 holding a single substrate W in a
horizontal attitude inside the processing chamber 2 and rotating
the substrate W around a vertical rotational axis A1 passing
through the center of the substrate W, a double-fluid nozzle 16
arranged to discharge liquid droplets of IPA that is an example of
an organic solvent onto an upper surface of the substrate W held by
the spin chuck 3, an organic solvent supplying unit (first organic
solvent supplying unit) 4 arranged to supply IPA to the
double-fluid nozzle 16, a gas supplying unit (gas supplying unit)
80 arranged to supply nitrogen gas as an example of a gas to the
double-fluid nozzle 16, a cylindrical processing cup 5 surrounding
the spin chuck 3, and a controller (control unit) 7 controlling
operations of apparatuses and opening/closing of valves provided in
the substrate processing apparatus 1.
[0055] The processing chamber 2 includes a box-shaped partition
wall 8, an FFU (fan filter unit) 9 as a blower unit delivering
clean air from an upper portion of the partition wall 8 into an
interior of the partition wall 8 (corresponding to an interior of
the processing chamber 2), and an exhaust apparatus 10 expelling
gas inside the processing chamber 2 from a lower portion of the
partition wall 8. The spin chuck 3 and the double-fluid nozzle 16
are housed and disposed within the partition wall 8.
[0056] The FFU 9 is disposed above the partition wall 8 and is
mounted on a roof of the partition wall 8. The FFU 9 delivers the
clean air into the processing chamber 6 from the roof of the
partition wall 13. The exhaust apparatus 10 is connected via an
exhaust duct 11, connected to an interior of the processing cup 5,
to a bottom portion of the processing cup 5 and suctions the
interior of the processing cup 5 from the bottom portion of the
processing cup 5. A down flow (downward flow) is formed inside the
processing chamber 6 by the FFU 9 and the exhaust apparatus 10.
[0057] As the spin chuck 3, a clamping type chuck, which clamps the
substrate W in horizontal directions to hold the substrate W
horizontally, is adopted. Specifically, the spin chuck 3 includes a
spin motor (substrate rotating unit) 12, a spin shaft 13 made
integral to a drive shaft of the spin motor 12, and a disk-shaped
spin base 14 mounted substantially horizontally on an upper end of
the spin shaft 13.
[0058] A plurality (not less than three, that is, for example, six)
of clamping members 15 are disposed at a peripheral edge portion of
an upper surface of the spin base 14. At the upper surface
peripheral edge portion of the spin base 14, the plurality of
clamping members 15 are disposed at suitable intervals on a
circumference corresponding to an outer peripheral shape of the
substrate W.
[0059] Also, the spin chuck 3 is not restricted to a clamping type
and, for example, a vacuum suction type arrangement (vacuum chuck)
that vacuum-suctions a rear surface of the substrate W to hold the
substrate W in a horizontal attitude and further performs rotation
around a vertical rotation axis in this state to rotate the
substrate W held by the spin chuck 3 may be adopted instead.
[0060] The double-fluid nozzle 16 has a basic form of a scan nozzle
capable of changing a position on a front surface of the substrate
W to which IPA is supplied (discharge region D1 (see FIG. 6B)). The
double-fluid nozzle 16 is mounted to a tip portion of a nozzle arm
17 extending substantially horizontally above the spin chuck 3. The
nozzle arm 17 is supported by an arm supporting shaft 18 extending
substantially vertically at a side of the spin chuck 3. An arm
swinging unit (nozzle moving unit) 19 is coupled to the arm
supporting shaft 18. The double-fluid nozzle 16 is arranged to be
capable of being moved above the spin chuck 3 between the
rotational axis A1 of the substrate W and a peripheral edge of the
substrate W by swinging the nozzle arm 17 by turning the arm
supporting shaft 18 by a driving force of the arm swinging unit 19.
It is also made capable of being moved from above the spin chuck 3
toward a home position at a side of the spin chuck 3.
[0061] The organic solvent supplying unit 4 includes an organic
solvent piping 20 supplying liquid IPA at ordinary temperature from
an IPA supply source to the double-fluid nozzle 16, an organic
solvent valve 21 switching between supplying and stopping the
supply of IPA from the organic solvent piping 20 to the
double-fluid nozzle 16, and a flow control valve 22 adjusting an
opening degree of the organic solvent piping 20 to adjust a flow
rate of IPA discharged from the double-fluid nozzle 16. As shall be
described later, the IPA discharged from the double-fluid nozzle 16
is used not only in an IPA liquid droplet discharging step (S4 of
FIG. 5) but also in an IPA liquid film forming step (S3 of FIG. 5)
and an IPA post-supplying step (S5 of FIG. 5). That is, second and
third organic solvent supplying units are realized by the organic
solvent supplying unit 4 and the double-fluid nozzle 16.
[0062] A gas supplying unit 80 includes a first gas piping 23
supplying a gas from a gas supply source and a first gas valve 24
switching between supplying and stopping the supply of gas from the
first gas piping 23 to the double-fluid nozzle 16. As the gas
supplied to the double-fluid nozzle 16, an inert gas, dry air, or
clean air, etc., maybe used besides nitrogen gas.
[0063] As shown in FIG. 2A, the double-fluid nozzle 16 has a
substantially circular columnar outer shape. The double-fluid
nozzle 16 includes an outer cylinder 26 constituting a casing and
an inner cylinder 27 fitted in an interior of the outer cylinder
26.
[0064] The outer cylinder 26 and the inner cylinder 27 are
respectively disposed coaxially on a central axis L in common and
are joined to each other. An internal space of the inner cylinder
27 is a rectilinear organic solvent flow passage 28 through which
the IPA from the organic solvent piping 20 flows. Also, a circular
cylindrical first gas flow passage 29, through which the gas
supplied from the first gas piping 23 flows, is formed between the
outer cylinder 26 and the inner cylinder 27.
[0065] The organic solvent flow passage 28 opens as an organic
solvent inlet 30 at an upper end of the inner cylinder 27. The IPA
from the organic solvent piping 20 is introduced via the organic
solvent inlet 30 into the organic solvent flow passage 28. Also,
the organic solvent flow passage 28 opens as a circular organic
solvent discharge port 31 having a center on the central axis L at
a lower end of the inner cylinder 27. The IPA introduced into the
organic solvent flow passage 28 is discharged from the organic
solvent discharge port 31.
[0066] On the other hand, the first gas flow passage 29 is a
circular cylindrical gap having a central axis in common with the
central axis L, is closed at upper end portions of the outer
cylinder 26 and the inner cylinder 27, and opens as a circular
annular gas discharge port 32, having a center on the central axis
L and surrounding the organic solvent discharge port 31, at lower
ends of the outer cylinder 26 and the inner cylinder 27. A lower
end portion of the first gas flow passage 29 is made smaller in
flow passage area than an intermediate portion in a length
direction of the first gas flow passage 29 and decreases in
diameter toward a lower side. Also, a gas inlet 33 in communication
with the first gas flow passage 29 is defined at an intermediate
portion of the outer cylinder 26.
[0067] The first gas piping 23 is connected in a state of
penetrating through the outer cylinder 26 to the gas inlet 33 and
an internal space of the first gas piping 23 is in communication
with the first gas flow passage 29. The gas from the first gas
piping 23 is introduced via the gas inlet 33 into the first gas
flow passage 29 and is discharged from the gas discharge port
32.
[0068] By opening the organic solvent valve 21 to make the IPA be
discharged from the organic solvent discharge port 31 while opening
the first gas valve 24 to make the gas be discharged from the gas
discharge port 32, the gas can be made to collide (mix) with the
IPA at a vicinity of the double-fluid nozzle 16 to thereby form
minute liquid droplets of the IPA and discharge the IPA in the form
of a mist.
[0069] On the other hand, by opening the organic solvent valve 21
to make the IPA be discharged from the organic solvent discharge
port 31 with the first gas valve 24 being closed, the IPA can be
discharged from the double-fluid nozzle 16 in a continuous stream
mode. Hereinafter, the IPA (organic solvent) in the continuous
stream mode shall be referred to as the "continuous stream of IPA
(organic solvent)."
[0070] As shown in FIG. 1, the processing cup 5 includes a
cylindrical wall 35 surrounding the spin chuck 3 and having, for
example, a circular cylindrical shape, a plurality of cups 36 and
37 (first and second cups 36 and 37) disposed fixedly between the
spin chuck 3 and the cylindrical wall 35, a plurality of guards 38
and 39 (first and second guards 38 and 39) arranged to receive the
IPA that is scattered to a periphery of the substrate W, and a
guard raising/lowering unit (guard raising/lowering unit) 40 that
raises and lowers each of the guards 38 and 39 independently. The
processing cup 5 is collapsible.
[0071] The cylindrical wall 35 surrounds a periphery of the spin
chuck 3. The cylindrical wall 35 is arranged to be capable of
storing IPA in its interior. The IPA stored in the cylindrical wall
35 is guided to a drain equipment (not shown). Also, an upstream
end of an exhaust duct 11 is connected to a predetermined location
in a circumferential direction of a lower end portion of the
cylindrical wall 35. The atmosphere inside the cylindrical wall 35
is exhausted through the exhaust duct 11 by the exhaust apparatus
10.
[0072] Each of the cups 36 and 37 defines an upwardly-open, annular
groove. The IPA guided to the first cup 36 is delivered through a
first piping (not shown) connected to a bottom portion of the
groove to a recovery equipment (not shown) or the drain equipment
(not shown). The IPA guided to the second cup 37 is delivered
through a second piping (not shown) connected to a bottom portion
of the groove to the recovery equipment (not shown) or the drain
equipment (not shown). The IPA used in processing the substrate W
is thereby subject to a recovery processing or a drain
processing.
[0073] Each of the guards 38 and 39 has a circular cylindrical
inclining portion 41 extending obliquely upward toward the
rotational axis A1 and a circular cylindrical guide portion 42
extending downward from a bottom end of the inclining portion 41.
An upper end portion of each inclining portion 41 constitutes an
inner peripheral portion of the guard 38 or 39 and has a larger
diameter than the substrate W and the spin base 14. The two
inclining portions 41 are overlapped vertically and the two guide
portions 42 are disposed coaxially. Each of the guide portions 42
of the guards 38 and 39 is capable of entering into and exiting
from the corresponding cup 36 or 37. The processing cup 5 is
extended or collapsed by the guard raising/lowering unit 40 raising
or lowering at least one of the two guards 38 and 39. In FIG. 1, a
state in which the processing cup 5 differs at the right side and
the left side of the rotational axis A1 is illustrated for the sake
of description.
[0074] The guard raising/lowering unit 40 raises and lowers each of
the guards 38 and 39 between an upper position, at which an upper
end of the guard is positioned higher than the substrate W, and a
lower position, at which the upper end of the guard is positioned
lower than the substrate W. The guard raising/lowering unit 40 is
capable of holding each of the guards 38 and 39 at any position
between the upper position and the lower position. The supplying of
IPA to the substrate W and the drying of the substrate W are
performed in a state where either of the guards 38 and 39 faces a
peripheral end surface of the substrate W. For example, if the
first guard 38 at the inner side is to be made to face the
peripheral end surface of the substrate W, the guards 38 and 39 are
disposed at the lower position (state shown at the right side in
FIG. 1). Also, if the second guard 39 is to be made to face the
peripheral end surface of the substrate W, the first guard 38 is
disposed at the lower position and the second guard 39 is disposed
at the upper position (state shown at the left side in FIG. 1).
[0075] As shown in FIG. 1, the substrate processing apparatus 1
further includes a gas discharge nozzle 6 arranged to perform gas
discharge above the substrate W held by the spin chuck 3. The gas
discharge nozzle 6 includes an annular upper gas discharge port 44
opening outward at an outer peripheral surface that is a side
surface of the gas discharge nozzle 6, an annular lower gas
discharge port 45 opening outward at the outer peripheral surface
that is the side surface of the gas discharge nozzle 6, and a
central gas discharge port 46 opening downward at a lower surface
of the gas discharge nozzle 6. The upper gas discharge port 44 is
disposed higher than the lower gas discharge port 45. The central
gas discharge port 46 is disposed lower than the upper gas
discharge port 44 and the lower gas discharge port 45 and further
inward (further toward a central axis A2 of the gas discharge
nozzle 6) than the upper gas discharge port 44 and the lower gas
discharge port 45. The upper gas discharge port 44 and the lower
gas discharge port 45 are slit-shaped discharge ports centered at
the central axis A2 of the gas discharge nozzle 6 and surrounding
an entire circumference of the side surface of the gas discharge
nozzle 6. An outer diameter of the upper gas discharge port 44 may
be equal to an outer diameter of the lower gas discharge port 45 or
may be greater or less than the outer diameter of the lower gas
discharge port 45.
[0076] The gas discharge nozzle 6 is a circular columnar member of
smaller diameter than the substrate W. A second gas piping 48 and a
third gas piping 49 are connected to the gas discharge nozzle 6.
Second and third gas valves 50 and 51 are respectively interposed
in the second and third gas pipings 48 and 49. The gas from the gas
supply source is introduced into the gas discharge nozzle 6 via the
second gas piping 48 and is supplied to the upper gas discharge
port 44 and the lower gas discharge port 45 via a second gas flow
passage (not shown). Also, the gas flowing inside the third gas
piping 49 is introduced into the gas discharge nozzle 6 via the
third gas piping 49 and is supplied to the central gas discharge
port 46 via a third gas flow passage (not shown). When the second
gas valve 50 is opened, the gas is discharged radially to a
periphery of the gas discharge nozzle 6 from the gas discharge
ports 44 and 45. When the third gas valve 51 is opened, the gas is
discharged downward from the central gas discharge port 46.
Although nitrogen gas is indicated as an example of the gas
supplied to the gas discharge nozzle 6, an inert gas, dry air, or
clean air, etc., may be used instead as the gas.
[0077] A gas nozzle moving unit 52 is coupled to the gas discharge
nozzle 6. The gas nozzle moving unit 52 makes the gas discharge
nozzle 6 turn around a vertical swinging axis (not shown) provided
at a side of the spin chuck 3. The gas nozzle moving unit 52 also
moves the gas discharge nozzle 6 in an up/down direction. When the
gas nozzle moving unit 52 raises or lowers the gas discharge nozzle
6 when the gas discharge nozzle 6 is positioned above the substrate
W, the gas discharge nozzle 6 is raised or lowered above the
substrate W so that a distance between the substrate W and the gas
discharge nozzle 6 changes. The gas nozzle moving unit 52 also
makes the gas discharge nozzle 6, be positioned, for example, at
any of a retracted position, an upper position (the position shown
in FIG. 1), and a proximity position (position shown in FIG. 6E).
The retracted position is a position at which the gas discharge
nozzle 6 is retracted to a side of the spin chuck 3 and the upper
position and the proximity position are positions at which the gas
discharge nozzle 6 is positioned above a central portion of the
substrate W. The upper position is a position above the proximity
position and the proximity position is a position at which the
lower surface of the gas discharge nozzle 6 is made more proximal
to an upper surface central portion of the substrate W than at the
upper position. The gas nozzle moving unit 52 is capable of holding
the gas discharge nozzle 6 at any position between the retracted
position and the upper position and any position between the upper
position and the proximity position.
[0078] FIG. 2B is a block diagram for explaining the electrical
structure of the substrate treatment apparatus 1. The controller 7
has an arrangement that includes a microcomputer. The controller 7
includes an operation unit including a CPU and the like, a storage
unit comprising a read-only memory device, and an input-output
unit. A program for the operation unit executes is stored in the
storage unit.
[0079] The controller 7 is connected to the operations of the
exhaust apparatus 10, the spin motor 12, the arm swinging unit 19,
the guard raising/lowering unit 40, the gas nozzle moving unit 52,
the organic solvent valve 21, the flow control valve 22, the first
gas valve 24, and the like. The controller 7 controls the
operations of the exhaust apparatus 10, the spin motor 12, the arm
swinging unit 19, the guard raising/lowering unit 40, the gas
nozzle moving unit 52, etc., in accordance with a predetermined
program. The controller 7 controls the opening and closing
operation etc. on the organic solvent valve 21, the flow control
valve 22, the first gas valve 24, etc., in accordance with a
predetermined program.
[0080] FIG. 3 is an enlarged sectional view of a vicinity of the
front surface of the substrate W to be processed by the substrate
processing apparatus 1.
[0081] The substrate W to be processed constitutes a base of a
MOSFET and includes the silicon substrate 61. At a surface layer
portion of the silicon substrate 61, trenches 62 are formed by
digging from the front surface. A plurality of the trenches 62 are
formed at fixed intervals in a right/left direction in FIG. 3 with
each extending in a direction orthogonal to a paper surface of FIG.
3. SiO.sub.2 63 (silicon oxide) is embedded in each trench 62. The
SiO.sub.2 63 forms element separating portions 64 that insulate
element forming regions from other regions. The element separating
portion 64 has an STI structure, with which the trench 62 is
refilled with an insulating material (SiO.sub.2 63). A front
surface of the SiO.sub.2 63 is made substantially flush with the
front surface of the silicon substrate 61.
[0082] FIGS. 4A to 4C are illustrative sectional views showing a
method for manufacturing the substrate W in order of process. As
shown in FIG. 4A, first, the trenches 62 are formed by reactive ion
etching in the surface layer portion of the silicon substrate 61.
Next, an SiO.sub.2 film 65 is formed by a vacuum CVD (chemical
vapor deposition) method on an upper surface of the silicon
substrate W and inside each trench 62 as shown in FIG. 4B. As shown
in FIG. 4B, the SiO.sub.2 film 65 fills the interiors of the
trenches 62 completely and is also formed on the silicon substrate
61 outside the trenches 62.
[0083] Next, portions of the SiO.sub.2 film 65 protruding outside
the respective trenches 62 are removed selectively by a CMP
(chemical mechanical polishing) method. A front surface of the
SiO.sub.2 film 65 is thereby made a flat surface that is
substantially flush with the front surface of the silicon substrate
61 and the element separating portions 64 are formed as shown in
FIG. 4C (first preliminary preparation step).
[0084] The element separating portions 64 are formed by polishing
the SiO.sub.2 film 65 by the CMP method and therefore particles 66,
such as SiO.sub.2 polishing scraps (slurry), etc., are present on
the surface layer portion of the substrate W immediately after
manufacture. The substrate processing apparatus 1 applies the
cleaning processing to the substrate W to remove the SiO.sub.2
polishing scraps and other particles 66 from the substrate W.
[0085] In such a cleaning processing, the use of SC1
(ammonia-hydrogen peroxide mixture) as a cleaning liquid may be
considered. However, when SC1 is used to clean the front surface of
the substrate W, the element separating portions 64 that are
constituted of SiO.sub.2 may become etched excessively and the
front surfaces of the element separating portions 64 may become
recessed. In this case, not only are the element separating
characteristics of the element separating portions 64 degraded but
the MOSFET may also become poor in flatness after manufacture of
the MOSFET.
[0086] On the other hand, in the cleaning processing according to
the present preferred embodiment, the front surface (upper surface)
of the substrate W is cleaned using IPA as the cleaning liquid. IPA
has only low etching power with respect to SiO.sub.2. The front
surface (upper surface) of the substrate W can thus be cleaned
satisfactorily without excessively etching the element separating
portions 64 that are constituted of SiO.sub.2.
[0087] FIG. 5 is a flowchart for describing a processing example of
the cleaning processing performed by the substrate processing
apparatus 1. FIGS. 6A to 6E are illustrative diagrams for
describing the processing example of the cleaning processing.
[0088] An example of the cleaning processing shall now be described
with reference to FIG. 1, FIG. 3, and FIG. 5. FIGS. 6A to 6E shall
be referenced where appropriate.
[0089] When the cleaning processing is to be applied to the
substrate W by the substrate processing apparatus 1, the substrate
W (in the state shown in FIG. 4C) after removal of the SiO.sub.2
film 65 (see FIG. 4B) by CMP is carried into the interior of the
processing chamber 2 (step S1 of FIG. 5). Specifically, the
controller 7 makes a hand (not shown) of a substrate transfer robot
(not shown), which holds the substrate W, enter into the interior
of the processing chamber 2 in a state where all nozzles are
retracted from above the spin chuck 3 and the first and second
guards 38 are lowered to the lower position so that the upper ends
of the first and second guards 38 and 39 are all disposed lower
than the position of holding of the substrate W by the spin chuck
3. The substrate W is thereby passed onto the spin chuck 3 and held
by the spin chuck 3 in a state where the major surface, which is to
be processed, is faced upward (substrate holding step).
[0090] Thereafter, the controller 7 controls the guard
raising/lowering unit 40 to raise both the first and second guards
38 and 39 to the upper positions and make the first guard 38 face
the peripheral end surface of the substrate W.
[0091] The controller 7 starts the rotation of the substrate W by
the spin motor 12 (step S2 of FIG. 5). The rotation speed of the
substrate W is raised to a predetermined first high rotation speed
(for example of approximately 1000 rpm) and is held at that first
high rotation speed.
[0092] When rotation of the substrate W reaches the first high
rotation speed, the controller 7 then performs the IPA liquid film
forming step (liquid film forming step; step S3 of FIG. 5) of
forming a liquid film of IPA on the upper surface of the substrate
W as shown in FIG. 6A. Specifically, the controller 7 controls the
arm swinging unit 19 so that the double-fluid nozzle 16 is moved
from the home position retracted to the side of the spin chuck 3 to
a central position (position indicated by solid lines in FIG. 6A),
at which the discharged IPA lands on an upper surface central
portion of the substrate W, and then kept still at the central
position. After the double-fluid nozzle 16 is disposed at the
central position, the controller 7 opens the organic solvent valve
21 while closing the first gas valve 24. A continuous stream of IPA
is thereby discharged from the double-fluid nozzle 16. The
discharge flow rate of the IPA from the double-fluid nozzle 16 is
set to a low flow rate (for example of 0.1 (liters/minute)) by
opening degree adjustment of the organic solvent piping 20 by the
flow control valve 22. Also, a period from the start of rotation of
the substrate W to the start of discharge of the IPA is, for
example, approximately 2.5 seconds.
[0093] As shown in FIG. 6A, the IPA discharged from the
double-fluid nozzle 16 lands on the upper surface of the substrate
W rotating at the first high rotation speed and thereafter receives
a centrifugal force due to the rotation of the substrate W and
flows outward along the upper surface of the substrate W. The IPA
is thus supplied to an entirety of the upper surface of the
substrate W and an IPA liquid film covering the entirety of the
upper surface of the substrate W is formed on the substrate W. The
IPA that has reached a peripheral edge portion upon flowing on the
upper surface of the substrate W is scattered toward sides of the
substrate W from the peripheral edge portion of the substrate
W.
[0094] As shown in FIG. 6A, the IPA that scatters from the
peripheral edge portion of the substrate W is received by an inner
wall of the first guard 38. The IPA that flows down along the inner
wall of the first guard 38 is received by the first cup 36 and
collected at a bottom portion of the first cup 36. The IPA
collected at the bottom portion of the first cup 36 is delivered
through the first piping (not shown) to the recovery equipment (not
shown) or the drain equipment (not shown).
[0095] When a predetermined period elapses from the start of
discharge of the IPA, the controller 7 controls the spin motor 12
to decelerate the rotation speed of the substrate W to a liquid
processing speed (for example of approximately 400 rpm) and
maintain the rotation speed at the liquid processing speed.
Thereafter, while sustaining the discharge of IPA from the
double-fluid nozzle 16 (while maintaining the discharge flow rate
of IPA as it is), the controller 7 controls the arm swinging unit
19 so that the double-fluid nozzle 16 is moved toward a peripheral
edge position (position indicated by solid lines in FIG. 6B), at
which the IPA discharged from the double-fluid nozzle 16 lands on
an upper surface peripheral edge portion of the substrate W, and
disposed at the peripheral edge position. The IPA liquid film
forming step (S3) is thereby ended. A processing period of the IPA
liquid film forming step (S3) is, for example, approximately 5 to 6
seconds.
[0096] Also, the rotation speed of the substrate W is decelerated
to the liquid processing speed prior to the end of the IPA liquid
film forming step (S3) because if the rotation of the substrate W
at the first high rotation speed is continued as it is, the IPA
supplied to the upper surface of the substrate W may volatilize,
causing the upper surface of the substrate W to dry and thereby
cause particle formation.
[0097] After the double-fluid nozzle 16 is disposed at the
peripheral edge position, the IPA liquid droplet discharging step
(liquid droplet discharging step; first rotating step; step S4 of
FIG. 5) of discharging liquid droplets of the IPA onto the upper
surface of the substrate W from the double-fluid nozzle 16 is
performed as shown in FIG. 6B. Specifically, the controller 7 opens
the first gas valve 24 while sustaining the discharge of IPA (while
maintaining the discharge flow rate of IPA as it is). The IPA and
the nitrogen gas, which is an example of the gas, are thereby
supplied simultaneously to the double-fluid nozzle 16 and the
supplied IPA and nitrogen gas are mixed at a vicinity of the
discharge port (organic solvent discharge port 31 (see FIG. 2B)) at
the exterior of the double-fluid nozzle 16. A jet of minute liquid
droplets of the IPA is thereby formed and the jet of IPA liquid
droplets is discharged from the double-fluid nozzle 16. A circular
discharge region D1 is thus formed on the upper surface of the
substrate W and the position of the discharge region D1 is disposed
at a peripheral edge portion of the substrate W.
[0098] Numerous IPA liquid droplets from the double-fluid nozzle 16
are blown onto the discharge region D1 of the substrate W and
therefore foreign matter (particles, etc.) attached to the
discharge region D1 can be removed physically by collision of the
IPA liquid droplets (physical cleaning). Also, the IPA liquid
droplets are blown onto the discharge region D1 in the state where
the entirety of the upper surface of the substrate W is covered by
the liquid film and thereafter reattachment of the foreign matter
to the substrate W is suppressed or prevented.
[0099] Also, the IPA liquid film covering the discharge region D1
is formed on the upper surface of the substrate W prior to the
discharge of the IPA liquid droplets. Therefore, at the start of
discharge of the IPA liquid droplets, the IPA liquid droplets
discharged from the double-fluid nozzle 16 collide against the IPA
liquid film covering the discharge region D1. Direct collision of
the IPA liquid droplets against the upper surface of the substrate
Win the dry state can thus be avoided at the start of discharge of
the IPA liquid droplets.
[0100] Also, by switching the supplying of the gas to the
double-fluid nozzle 16 from the stopped state to the supplying
state while sustaining the supplying of the IPA to the double-fluid
nozzle 16, the IPA discharged from the double-fluid nozzle 16 can
be switched from the continuous stream mode to the liquid droplet
mode. That is, the IPA supplied to the upper surface of the
substrate W in the IPA liquid film forming step (S3) is discharged
from the double-fluid nozzle 16.
[0101] Also, in parallel to the discharge of the jet of IPA liquid
droplets from the double-fluid nozzle 16, the controller 7 controls
the arm swinging unit 19 to make the double-fluid nozzle 16 move
back and forth horizontally between the central position and the
peripheral edge position. Specifically, first, the double-fluid
nozzle 16 disposed at the peripheral edge position is moved toward
the central position. The position of the discharge region D1 is
thereby moved along the upper surface of the substrate W toward the
central axis A1 while being covered by the IPA liquid film.
[0102] When the double-fluid nozzle 16 reaches the central
position, the controller 7 controls the arm swinging unit 19 to
reverse the swinging direction of the nozzle arm 17. The
double-fluid nozzle 16 is thus made to start movement from the
central position toward the peripheral edge position. The position
of the discharge region D1 is thereby moved along the upper surface
of the substrate W toward the peripheral edge portion of the
substrate W while being covered by the IPA liquid film. When the
double-fluid nozzle 16 reaches the peripheral edge position, the
controller 7 controls the arm swinging unit 19 to reverse the
swinging direction of the nozzle arm 17. The position of the
discharge region D1 is thereby moved along the upper surface of the
substrate W toward the central axis A1. The position of the
discharge region D1 is thus moved back and forth between the
peripheral edge portion of the substrate W and the central portion
of the substrate W.
[0103] The double-fluid nozzle 16 is moved between the central
position and the peripheral edge position while rotating the
substrate W, and therefore the upper surface of the substrate W is
scanned by the discharge region D1 and the position of the
discharge region D1 passes through the entirety of the upper
surface of the substrate W. The IPA discharged from the
double-fluid nozzle 16 is thus supplied to the entirety of the
upper surface of the substrate W and the entirety of the upper
surface of the substrate W is processed uniformly. The IPA supplied
to the upper surface of the substrate W is scattered from the
peripheral edge portion of the substrate W toward the sides of the
substrate W.
[0104] A moving speed of the double-fluid nozzle 16 (that is, a
scanning speed of the discharge region D1) is set, for example, to
approximately 30 to 80 mm/second.
[0105] As shown in FIG. 6B, the IPA that scatters from the
peripheral edge portion of the substrate W is received by the inner
wall of the first guard 38. The IPA that flows down along the inner
wall of the first guard 38 is received by the first cup 36 and
collected at the bottom portion of the first cup 36. The IPA
collected at the bottom portion of the first cup 36 is delivered
through the first piping (not shown) to the recovery equipment (not
shown) or the drain equipment (not shown).
[0106] When a predetermined period elapses from the start of supply
of gas with respect to the double-fluid nozzle 16, the controller 7
controls the spin motor 12 to accelerate the rotation speed of the
substrate W to a second high rotation speed (for example of
approximately 1000 rpm) and thereafter maintain the rotation speed
at the second high rotation speed. Also, while sustaining the
discharge of IPA, the controller 7 controls the arm swinging unit
19 so that the double-fluid nozzle 16 is moved toward the central
position and disposed at the central position. The IPA liquid
droplet discharging step (S4) is thereby ended. A processing period
of the IPA liquid droplet discharging step (S4) is, for example,
approximately 8 to 96 seconds.
[0107] After the double-fluid nozzle 16 is disposed at the central
position, an IPA post-supplying step (post-supplying step; second
rotating step; step S5 of FIG. 5) of supplying a continuous stream
of IPA to the upper surface of the substrate W is performed as
shown in FIG. 6C. Specifically, the controller 7 closes the first
gas valve 24 that was open up to this point. The supplying of the
gas with respect to the double-fluid nozzle 16 is thereby stopped
and the continuous stream of IPA is discharged from the
double-fluid nozzle 16 (the discharge flow rate of IPA is 0.1
(liters/minute)). By switching the supplying of the gas to the
double-fluid nozzle 16 from the supplying state to the stopped
state while sustaining the supplying of the IPA to the double-fluid
nozzle 16, the IPA discharged from the double-fluid nozzle can be
switched from the liquid droplet mode to the continuous stream
mode.
[0108] The continuous stream of IPA discharged from the
double-fluid nozzle 16 lands on the upper surface of the substrate
W rotating at the second high rotation speed and thereafter
receives a centrifugal force due to the rotation of the substrate W
and flows outward along the upper surface of the substrate W. The
IPA is thus supplied to the entirety of the upper surface of the
substrate W and an IPA liquid film covering the entirety of the
upper surface of the substrate W is formed on the substrate W as
shown in FIG. 6C. The IPA that has reached the peripheral edge
portion upon flowing on the upper surface of the substrate W is
scattered toward the sides of the substrate W from the peripheral
edge portion of the substrate W. In the IPA post-supplying step
(S5), the foreign matter removed from the substrate W upper surface
by the physical cleaning in the IPA liquid droplet discharging step
(S4) is rinsed off by the IPA.
[0109] Also, the IPA liquid film formed on the upper surface of the
substrate W can be levelled prior to a drying step (S7) because the
IPA liquid film is formed on the upper surface of the substrate Win
the IPA post-supplying step (S5).
[0110] As shown in FIG. 6C, the IPA that scatters from the
peripheral edge portion of the substrate W is received by the inner
wall of the first guard 38. The IPA that flows down along the inner
wall of the first guard 38 is received by the first cup 36 and
collected at the bottom portion of the first cup 36. The IPA
collected at the bottom portion of the first cup 36 is delivered
through the first piping (not shown) to the recovery equipment (not
shown) or the drain equipment (not shown).
[0111] When a predetermined period elapses from the start of
discharge of the IPA, the controller 7 controls the spin motor 12
to decelerate the rotation speed of the substrate W to a medium
rotation speed (for example of approximately 500 rpm) and maintain
the rotation speed at the medium rotation speed. Thereafter, the
controller 7 controls the organic solvent valve 21 to stop the
discharge of IPA from the double-fluid nozzle 16 and controls the
arm swinging unit 19 so that the double-fluid nozzle 16 is
retracted from the central position (processing position) to the
home position. The IPA post-supplying step (S5) is ended by
stoppage of discharge of IPA from the double-fluid nozzle 16. A
processing period of the IPA post-supplying step (S5) is, for
example, approximately 5 to 6 seconds.
[0112] Also, the rotation speed of the substrate W is decelerated
to the medium rotation speed prior to the end of the IPA
post-supplying step (S5) because if the rotation of the substrate W
at the second high rotation speed is continued as it is, the IPA
supplied to the upper surface of the substrate W may volatilize,
causing the upper surface of the substrate W to dry and thereby
cause particle formation.
[0113] After the discharge of IPA from the double-fluid nozzle 16
is stopped, the controller 7 controls the spin motor 12 to
decelerate the rotation speed of the substrate W, rotating at the
medium rotation speed, to a low rotation speed (for example of
approximately 10 rpm) and maintain the rotation speed at the low
rotation speed. The low rotation speed may be zero (that is,
stoppage of rotation).
[0114] After the substrate W reaches the low rotation speed, the
controller 7 controls the guard raising/lowering unit 40, while
maintaining the rotation speed of the substrate W at the low
rotation speed, to lower the first guard 38 from the upper position
to the lower position while maintaining the second guard 39 at the
upper position and thereby make the second guard 39 face the
peripheral end surface of the substrate W as shown in FIG. 6D. That
is, the guard facing the peripheral end surface of the substrate W
is switched (changed (step S6 of FIG. 5: facing guard changing
step)) from the first guard 38 to the second guard 39.
[0115] After the second guard 39 is disposed to face the peripheral
end surface of the substrate W, the controller 7 executes the
drying step (step S7 of FIG. 5) as shown in FIG. 6E.
[0116] Specifically, the controller 7 controls the spin motor 12 to
increase the rotation speed of the substrate W from the low
rotation speed. Also, the controller 7 controls the gas nozzle
moving unit 52 to move the gas discharge nozzle 6 from the upper
position to the proximity position. After the gas discharge nozzle
6 is disposed at the proximity position, the controller 7 opens the
second gas valve 50 and the third gas valve 51 to make nitrogen
gas, which is an example of the gas, be discharged from the three
gas discharge ports (the upper gas discharge port 44, the lower gas
discharge port 45, and the central gas discharge port 46). Three
annular gas streams overlapping in the up/down direction are
thereby formed above the substrate W and the upper surface of the
substrate W is protected by the three annular gas streams.
[0117] After starting the discharge of nitrogen gas from the three
gas discharge ports 44, 45, and 46 of the gas discharge nozzle 6,
the controller 7 controls the spin motor 12 to make the substrate W
rotate at a predetermined drying speed (for example of
approximately 1000 rpm). The IPA on the substrate W is thereby spun
off outward and the substrate W dries. Also, the drying of the
substrate W is performed in a state where the upper surface of the
substrate W is covered by the three annular gas streams, and
therefore particles and other foreign matter and IPA mist that are
suspended inside the processing chamber 2 are suppressed or
prevented from attaching to the substrate W during the drying step
(S7).
[0118] The IPA liquid droplets that scatter from the peripheral
edge portion of the substrate W in the drying step (S7) are
received by an inner wall of the second guard 39 as shown in FIG.
6E. The IPA that flows down along the inner wall of the second
guard 39 is received by the second cup 37 and collected at a bottom
portion of the second cup 37. The IPA collected at the bottom
portion of the second cup 37 is delivered through the second piping
(not shown) to the recovery equipment (not shown) or the drain
equipment (not shown).
[0119] When the drying step (S7) has been performed for a
predetermined period (for example of 12 seconds), the controller 7
drives the spin motor 12 to stop the rotation of the spin chuck 3
(rotation of the substrate W) (step S8 of FIG. 5). After stopping
the rotation of the substrate W by the spin chuck 3, the controller
7 closes the second gas valve 50 and the third gas valve 51 to stop
the discharge of gas from the three gas discharge ports 44, 45, and
46. After stopping the discharge of gas from the three gas
discharge ports 44, 45, and 46, the controller 7 controls the gas
nozzle moving unit 52 to make the gas discharge nozzle 6 retract to
the periphery of the spin chuck 3.
[0120] The cleaning processing of the single substrate W is thereby
ended and, as when the substrate W was carried in, the controller 7
carries the processed substrate W out from inside the processing
chamber 2 by means of the transfer robot (step S9 of FIG. 5).
[0121] First and second cleaning tests shall now be described.
[0122] In each of the first and second cleaning tests, a substrate
processing method (cleaning processing) according to an example
described below is applied to a sample.
[0123] Example: A bare silicon substrate W (outer diameter: 300
(mm)) was adopted as the sample and IPA was adopted as the organic
solvent. The substrate processing apparatus 1 was used to execute
the processing example of the cleaning processing shown in FIG. 5
to FIG. 6E described above on the sample held by the spin chuck 3
(see FIG. 1) and put in a rotating state.
[0124] Also, in the first cleaning test, a substrate processing
method (cleaning processing) according to a comparative example
described below is applied to a sample.
[0125] Comparative example: A bare silicon substrate W (outer
diameter: 300 (mm)) was adopted as the sample and IPA was adopted
as the organic solvent. The substrate processing apparatus 1 was
used to execute a cleaning processing on the sample held by the
spin chuck 3 (see FIG. 1) and put in a rotating state. The cleaning
processing according to the comparative example differs from the
processing example of the cleaning processing shown in FIG. 5, FIG.
6B, FIG. 6D, and FIG. 6E described above in the point that both the
IPA liquid film forming step (S3 of FIG. 5) and the IPA
post-supplying step (S5 of FIG. 5) are abolished and is the same as
the processing example of the cleaning processing described above
in regard to other points.
<First Cleaning Test>
[0126] For the example, a distribution and number of particles on
the front surface of the substrate W after the cleaning processing
were measured. The cleaning test was performed twice and test
results of the first cleaning test performed with the example are
shown respectively in FIGS. 7A and 7B.
[0127] On the front surface of the substrate W after the cleaning
test shown in FIG. 7A, 47 particles of not less than 26 nm were
present. The number of particles on the front surface of the
substrate W before performing the test was 46 and although this
means that the number of particles increased by one, this is within
the range of measurement error. It is therefore believed that there
is no practical increase or decrease in the number of particles on
the substrate W front surface before and after the cleaning
test.
[0128] Also, on the front surface of the substrate W after the
cleaning test shown in FIG. 7B, 32 particles of not less than 26 nm
were present. The number of particles on the front surface of the
substrate W before performing the cleaning test was 25 and although
this means that the number of particles increased by seven, this is
within the range of measurement error. It is therefore believed
that there is no practical increase or decrease in the number of
particles on the substrate W front surface before and after the
cleaning test.
[0129] It can thus be understood that when both the IPA liquid film
forming step (S3 of FIG. 5) and the IPA post-supplying step (S5 of
FIG. 5) are performed, particles formed in the IPA liquid droplet
discharging step (S4 of FIG. 5) can be suppressed effectively from
remaining on the substrate W.
[0130] Meanwhile, for the comparative example, the distribution and
number of particles on the front surface of the substrate W after
the cleaning processing were measured. A test result of the first
cleaning test performed with a comparative example is shown in FIG.
8. A measurement result of the particle distribution is shown in
FIG. 8. White portions appearing in FIG. 8 are particles. On the
front surface of the substrate W after the cleaning test, not less
than approximately 45000 particles were present. It can thus be
understood that when both the IPA liquid film forming step (S3 of
FIG. 5) and the IPA post-supplying step (S5 of FIG. 5) are not
performed, many of the particles formed in the IPA liquid droplet
discharging step (S4 of FIG. 5) remain on the front surface of the
substrate W.
[0131] A description regarding the distribution of particles shall
now be provided. In each of the examples of FIG. 7A and FIG. 7B,
biasing of the particles on the substrate W after the cleaning test
was not seen in particular. On the other hand, with the comparative
example of FIG. 8, a pattern where especially many particles form
in a double annular form at the peripheral edge portion of the
substrate W was seen. A reason for formation of the particle
pattern at the peripheral edge portion of the substrate W is
considered to be that the IPA liquid film forming step (S3 of FIG.
5) was not performed before the IPA liquid droplet discharging step
(S4 of FIG. 5). That is, in the IPA liquid droplet discharging step
(S4 of FIG. 5), the double-fluid nozzle 16 starts scanning the
substrate W from the peripheral edge portion of the substrate W.
The IPA liquid droplets from the double-fluid nozzle 16 immediately
after the start of discharge vary greatly in particle diameter. It
is known that particle characteristics of the substrate W after
cleaning degrade when the jet of IPA liquid droplets, which vary
greatly in particle diameter, is made to collide against the
substrate W front surface. In each of the examples of FIG. 7A and
FIG. 7B, the IPA liquid film forming step (S3 of FIG. 5) is
performed before the IPA liquid droplet discharging step (S4 of
FIG. 5) and therefore the jet of IPA liquid droplets collide not
directly against the front surface of the substrate W but collide
via the IPA liquid film. The particle characteristics at the
peripheral edge portion of the substrate W (that is, at the
location at which the jet of IPA liquid droplets is oriented
immediately after the start of discharge) are thus satisfactory. On
the other hand, with the comparative example of FIG. 8, the IPA
liquid film forming step (S3 of FIG. 5) is not performed and the
jet of IPA liquid droplets, which vary greatly in particle
diameter, collide against the front surface of the substrate W
without intervention of an IPA liquid film. The particle
characteristics are thus degraded at the peripheral edge portion of
the substrate W.
[0132] Further, a reason as to why the mode of particles exhibit a
double annular form at the peripheral edge portion of the substrate
W in FIG. 8 is considered to be as follows. That is, in the
circular discharge region D1 (see FIG. 6B) on the upper surface of
the substrate W, whereas a large amount of liquid droplets are
supplied to a central portion of the discharge region D1, only a
minute amount of liquid droplets are supplied to an outer
peripheral portion of the discharge region D1. Therefore variation
of particle diameter of the IPA liquid droplets tends to be
significant and particles form readily at the outer peripheral
portion of the discharge region D1. This is considered to be a
factor for the double annular form of particles.
[0133] <Second Cleaning Test>
[0134] As the rotation speed of the substrate W increases, the IPA
liquid film in the IPA liquid droplet discharging step (S4 of FIG.
5) becomes thinner and the liquid droplets of the IPA jet begin to
act directly on the upper surface of the substrate W. Also as the
rotation speed of the substrate W increases, gaps do no form in a
locus of the discharge region D1 (see FIG. 6B) and the entirety of
the substrate W begins to be scanned by the discharge region D1.
Removal performance of the cleaning processing is thus improved as
the rotation speed of the substrate W increases.
[0135] On the other hand, as the rotation speed of the substrate W
becomes high, particles begin to form slightly at a central portion
of the upper surface of the substrate W (this state shall
hereinafter referred to as the "particle mode"). FIG. 9 is a
schematic plan view for describing the particle mode. When the
rotation speed of the substrate W is high, a centrifugal force acts
on the IPA supplied to the substrate W and the IPA moves toward the
peripheral edge portion of the substrate W. In particular, the
central portion of the upper surface of the substrate W dries in
some cases in a state where the discharge region D1 (see FIG. 6B)
is disposed at the peripheral edge portion of the substrate W. It
may be considered that particles are formed slightly (the particle
mode became manifest) due to the drying of the central portion of
the substrate W.
[0136] In the second cleaning test, the rotation speed of the
substrate W in the IPA liquid droplet discharging step (S4 of FIG.
5) of the example was varied at 300 rpm, 400 rpm, 500 rpm, and 1000
rpm. A degree of cleanness of the front surface of the substrate W
(removal performance (cleaning performance) of the cleaning
processing) after the cleaning processing and whether or not the
particle mode occurred on the substrate W after the cleaning
processing were respectively observed visually. Also, the number of
particles of size not less than 26 (nm) on the front surface of the
substrate W after the cleaning processing was also measured.
[0137] The test results of the second cleaning test are shown in
FIG. 10. FIG. 10 shows, for the example, relationships of the
rotation speed of the substrate W with respect to the occurrence of
the particle mode after the cleaning processing and the removal
performance of the cleaning processing. In regard to whether or not
the particle mode occurred, "Good" is indicated in a case where the
particle mode does not occur and "Insufficient" is indicated in a
case where the particle mode occurs. Also, in regard to the degree
of cleanness of the substrate W (removal performance (cleaning
performance) of the cleaning processing), "Good" is indicated in a
case where the degree of cleanness is satisfactory and
"Insufficient" is indicated in a case where the degree of cleanness
is poor. Also, the number of particles that formed at the central
portion of the front surface of the substrate W after the cleaning
processing is indicated in parenthesis.
[0138] It can be understood from FIG. 10 that the removal
performance of the cleaning processing is low when the rotation
speed of the substrate Win the IPA liquid droplet discharging step
(S4 of FIG. 5) is not more than 300 rpm. As one cause, it is
considered that the liquid film on the substrate W becomes too
thick and consequently a sufficient amount of IPA liquid droplets
do not reach the upper surface of the substrate W in the IPA liquid
droplet discharging step (S4 of FIG. 5). Also, as another cause, it
is considered that the rotation speed of the substrate W is too
slow with respect to the moving speed of the discharge region D1,
causing gaps to form in the locus of the discharge region D1 (see
FIG. 6B) so that, consequently, the entirety of the substrate W
cannot be scanned by the discharge region D1.
[0139] It can be understood from FIG. 10 that the particle mode
occurs when the rotation speed of the substrate W in the IPA liquid
droplet discharging step (S4) is not less than 500 rpm.
[0140] It can be understood from the above that the removal
performance of the cleaning processing is high and the occurrence
of the particle mode can be suppressed when the rotation speed of
the substrate W exceeds 300 rpm and is less than 500 rpm (and
especially when the rotation speed is approximately 400 rpm).
[0141] As described above, with the first preferred embodiment, IPA
liquid droplets are discharged from the double-fluid nozzle 16
toward the discharge region D1 within the upper surface of the
substrate W. Foreign matter (particles, etc.) attached to the
discharge region D1 are removed physically by collision of the IPA
liquid droplets against the upper surface of the substrate W. The
upper surface of the substrate W can thereby be cleaned
satisfactorily.
[0142] Also, the IPA liquid film that covers the discharge region
D1 within the upper surface of the substrate W is formed before the
discharge of the IPA liquid droplets. Therefore, the IPA liquid
droplets discharged from the double-fluid nozzle 16 collide against
the IPA liquid film covering the discharge region D1. The IPA
liquid droplets can thus be prevented from directly colliding
against the upper surface of the substrate Win the dry state at the
start of IPA liquid droplet discharge at which the particle
diameter distribution of the IPA liquid droplets discharged from
the double-fluid nozzle 16 is unstable. Formation of particles in
accompaniment with the execution of the IPA liquid droplet
discharging step (S4) can thus be suppressed.
[0143] By the above, the upper surface of the substrate W can be
processed satisfactorily using the IPA liquid droplets from a
double-fluid nozzle 16 while suppressing the formation of
particles.
[0144] Also, damage of the substrate W in accompaniment with the
supplying of liquid droplets of the IPA jet can be suppressed to
the minimum because the discharge region D1 within the upper
surface of the substrate W is protected by the IPA liquid film.
[0145] As described above, by setting the rotation speed of the
substrate W to 400 rpm and setting the discharge flow rate of IPA
from the double-fluid nozzle 16 at a low value of 0.1
liters/minute, the thickness of the IPA liquid film on the upper
surface of the substrate W can be kept thin. The particle
performance of the cleaning processing using IPA can thereby be
improved. Moreover, under these conditions, the formation of
particles (the occurrence of the particle mode) in accompaniment
with the IPA liquid droplet discharging step (S4) can be suppressed
effectively.
[0146] Also, in the IPA liquid film forming step (S3), the IPA
supplied to the upper surface of the substrate W is discharged from
the double-fluid nozzle 16.
[0147] If, for instance, a liquid film forming nozzle (not shown)
is provided separately from the double-fluid nozzle 16 and the IPA
to be supplied to the upper surface of the substrate W is made to
be discharged from the liquid film forming nozzle in the IPA liquid
film forming step (S3), a waiting time until the start of IPA
discharge from the double-fluid nozzle 16 (start of the IPA liquid
droplet discharging step (S4)) arises after the end of execution of
the IPA liquid film forming step (S3) due to movement of the
double-fluid nozzle 16 and the liquid film forming nozzle, etc.,
and the upper surface of the substrate W may dry during the waiting
time.
[0148] On the other hand, with the first preferred embodiment, the
IPA to be supplied to the upper surface of the substrate W is
discharged from the double-fluid nozzle 16 in the IPA liquid film
forming step (S3). Therefore, during the transition from the IPA
liquid film forming step (S3) to the IPA liquid droplet discharging
step (S4), the IPA can be supplied without interruption to the
upper surface of the substrate W. Drying of the upper surface of
the substrate W during the transition from the IPA liquid film
forming step (S3) to the IPA liquid droplet discharging step (S4)
can thus be suppressed. The formation of particles can thus be
suppressed effectively during the transition from the IPA liquid
film forming step (S3) to the liquid droplet discharging step
(S4).
[0149] Also, in the IPA post-supplying step (S5) performed after
the IPA liquid droplet discharging step (S4), a continuous stream
of the IPA is supplied to the upper surface of the substrate W. The
foreign matter removed from the substrate W upper surface by the
physical cleaning in the IPA liquid droplet discharging step (S4)
can thus be rinsed off by the IPA and reattachment of the foreign
matter onto the upper surface of the substrate W can thereby be
suppressed or prevented.
[0150] Also, the rotation speed of the substrate W in the IPA
post-supplying step (S5) is a higher speed (the second high
rotation speed) than that in the IPA liquid droplet discharging
step (S4) and therefore a large centrifugal force acts on the IPA
supplied to the upper surface of the substrate W. The foreign
matter removed from the upper surface of the substrate W by the
physical cleaning can thereby be spun off from sides of the
substrate W together with the IPA and remaining of the foreign
matter on the upper surface of the substrate W can thus be
suppressed or prevented.
[0151] Also, in the IPA post-supplying step (S5), the IPA supplied
to the upper surface of the substrate W is discharged from the
double-fluid nozzle 16.
[0152] If, for instance, a post-supplying nozzle (not shown) is
provided separately from the double-fluid nozzle 16 and the IPA to
be supplied to the upper surface of the substrate W is made to be
discharged from the post-supplying nozzle in the IPA post-supplying
step (S5), a waiting time until the start of IPA discharge from the
post-supplying nozzle (start of the IPA post-supplying step (S5))
arises after the end of execution of the IPA liquid droplet
discharging step (S4) due to movement of the double-fluid nozzle 16
and the post-supplying nozzle, etc., and the upper surface of the
substrate W may dry during the waiting time.
[0153] On the other hand, with the first preferred embodiment, the
IPA to be supplied to the upper surface of the substrate W is
discharged from the double-fluid nozzle 16 in the IPA
post-supplying step (S5). Therefore, during the transition from the
IPA liquid droplet discharging step (S4) to the IPA post-supplying
step (S5), the IPA can be supplied without interruption to the
upper surface of the substrate W, and drying of the upper surface
of the substrate W during the transition from the IPA liquid
droplet discharging step (S4) to the IPA post-supplying step (S5)
can thus be suppressed effectively. Formation of particles during
the transition from the IPA liquid droplet discharging step (S4) to
the IPA post-supplying step (S5) can thus be suppressed
effectively.
[0154] Also, in the IPA liquid droplet discharging step (S4), in
which the upper surface of the substrate W is physically cleaned by
the IPA liquid droplets, the IPA expelled from the substrate W
contains the foreign matter removed from the substrate W. During
the IPA liquid drop discharging step (S4), the first guard 38 faces
the peripheral end surface of the substrate W and the IPA that
contains the foreign matter becomes attached to the first guard
38.
[0155] In the drying step (S7) according to the first preferred
embodiment, the second guard 39 is made to face the peripheral end
surface of the substrate W instead of the first guard 38 that has
the foreign-matter-containing IPA attached thereto. Therefore
during the drying step (S7), the substrate W after the cleaning
processing can be suppressed effectively from being contaminated by
the IPA attached to the guard facing the peripheral end surface of
the substrate W. The substrate W can thereby be processed
satisfactorily using the IPA liquid droplets from the double-fluid
nozzle 16 while suppressing the formation of particles even more
effectively.
[0156] FIG. 11 is an illustrative diagram of a portion of a
substrate processing apparatus 101 which executes a substrate
processing method according to a second preferred embodiment of the
present invention. FIGS. 12A and 12B are illustrative diagrams for
describing the IPA liquid droplet discharging step (S4) in a
cleaning processing according to the second preferred embodiment of
the present invention.
[0157] In FIG. 11 and FIGS. 12A and 12B, portions corresponding to
respective portions indicated in the first preferred embodiment
shall be indicated by attaching the same reference symbols as in
the case of FIG. 1 to FIG. 10 and description thereof shall be
omitted.
[0158] The substrate processing apparatus 101 according to the
second preferred embodiment differs from the substrate processing
apparatus 1 according to the first preferred embodiment in the
point of being provided with an additional organic solvent
supplying unit (fourth organic solvent supplying unit) 102 in
addition to the organic solvent supplying unit 4.
[0159] The additional organic solvent supplying unit 102 includes
an organic solvent nozzle 103 constituted of a straight nozzle. The
organic solvent nozzle 103 is a nozzle that discharges IPA in a
continuous stream mode and is mounted on the nozzle arm 17.
Therefore, when the nozzle arm 17 is swung to move the position of
the discharge region D1 (see FIGS. 12A and 12B), the double-fluid
nozzle 16 and the organic solvent nozzle 103 move while keeping
fixed a positional relationship of the double-fluid nozzle 16 and
the organic solvent nozzle 103. The organic solvent nozzle 103 is
mounted on the nozzle arm 17 so that an IPA supply region Su10 in
the upper surface of the substrate W is positioned at an outer side
in a radial direction with respect to the discharge region D1.
[0160] The additional organic solvent supplying unit 102 includes
an additional organic solvent piping 104 guiding IPA from an IPA
supply source to the organic solvent nozzle 103 and an additional
organic solvent valve 105 opening and closing the additional
organic solvent piping 104. When the additional organic solvent
valve 105 is opened, liquid IPA at ordinary temperature from the
IPA supply source is supplied to the organic solvent nozzle 103
through the additional organic solvent piping 104. A continuous
stream of the IPA is thereby discharged from the organic solvent
nozzle 103.
[0161] As shown indicated by the two-dot-and-dash line in FIG. 2B,
in addition to the description of the controller 7 in the first
embodiment, the controller 7 further is connected to the operations
of the additional organic solvent valve 105, and the like. The
controller 7 controls the opening and closing operation etc. on the
additional organic solvent valve 105, etc., in accordance with a
predetermined program.
[0162] In the cleaning processing according to the second preferred
embodiment, a cleaning processing equivalent to the cleaning
processing according to the first preferred embodiment (the
cleaning processing shown in FIG. 5) is executed. In the IPA liquid
droplet discharging step (S4), discharge of the continuous stream
of IPA from the organic solvent nozzle 103 is performed in parallel
to the discharge of IPA liquid droplets from the double-fluid
nozzle 16. The step differs from the IPA liquid droplet discharging
step (S4) according to the first preferred embodiment in this
point. The point of difference shall now be described.
[0163] In the IPA liquid droplet discharging step (S4), the
controller 7 controls the arm swinging unit 19 to make the
double-fluid nozzle 16, which is discharging the jet of IPA liquid
droplets, move back and forth horizontally between the central
position and the peripheral edge position, and the position of the
discharge region D1 is thereby moved between the central portion of
the substrate Wand the peripheral edge portion of the substrate W
(discharge region moving step). The organic solvent nozzle 103 is
also moved back and forth horizontally accordingly.
[0164] When as shown in FIG. 12A, the double-fluid nozzle 16 is
being moved from the peripheral edge position toward the central
position, the controller 7 opens the additional organic solvent
valve 105 to make a continuous stream of IPA be discharged from the
organic solvent nozzle 103 (additional organic solvent supplying
step). The continuous stream of IPA is thereby supplied to a
rearward position with respect to a direction of progress of the
discharge region D1 in the upper surface of the substrate W. On the
other hand, when as shown in FIG. 12B, the double-fluid nozzle 16
is being moved from the central position toward the peripheral edge
position, the controller 7 closes the additional organic solvent
valve 105 so that the IPA is not discharged from the organic
solvent nozzle 103.
[0165] In other words, the continuous stream of IPA is discharged
from the organic solvent nozzle 103 when the supply region Su1 is
positioned rearward with respect to the direction of progress of
the discharge region D1, and the IPA is not discharged from the
organic solvent nozzle 103 when the IPA supply region Su1 is
positioned forward with respect to the direction of progress of the
discharge region D1.
[0166] With the second preferred embodiment, regardless of where in
the upper surface of the substrate W the position of the discharge
region D1 is disposed, the IPA is supplied separately to a vicinity
of the position of the discharge region D1. If the upper surface of
the substrate W dries during the IPA liquid droplet discharging
step (S4), particles may form in the dried region. However, the IPA
is supplied to the vicinity of the position of the discharge region
D1 and therefore drying of the upper surface of the substrate W
during the IPA liquid droplet discharging step (S4) can be
prevented.
[0167] If, for instance, the IPA supply region Su1 is disposed at a
forward position with respect to the direction of progress of the
discharge region D1, the IPA liquid film at the discharge region D1
becomes thick. If the liquid film that covers the discharge region
D1 is thick, the IPA may splash in accompaniment with the discharge
of the IPA liquid droplets onto the discharge region. Contaminants
contained in the IPA may scatter to the periphery due to the
splashing of the IPA and may cause particle formation.
[0168] With the second preferred embodiment, the IPA is supplied
only to the rearward position with respect to the direction of
progress of the discharge region D1 and therefore the IPA liquid
film at the discharge region D1 can be kept thin while preventing
the drying of the upper surface of the substrate W. Splashing of
the IPA discharged onto the discharge region D1 can thus be
suppressed. Formation of particles in accompaniment with the
execution of the IPA liquid droplet discharging step (S4) can
thereby be suppressed more effectively.
[0169] Although two preferred embodiments of the present invention
have been described above, the present invention may be implemented
in yet other modes.
[0170] For example, in the second preferred embodiment, the organic
solvent nozzle 103 may be mounted on the nozzle arm 17 so that the
IPA supply region Su1 in the upper surface of the substrate W is
positioned at an inner side in the radial direction with respect to
the discharge region D1. In this case, the continuous stream of IPA
is discharged from the organic solvent nozzle 103 when the
double-fluid nozzle 16 is moved from the central position toward
the peripheral edge position. On the other hand, the IPA is not
discharged from the organic solvent nozzle 103 when the
double-fluid nozzle 16 is moved from the peripheral edge position
toward the central position. In other words, the continuous stream
of IPA is discharged from the organic solvent nozzle 103 when the
supply region Su1 is positioned rearward with respect to the
direction of progress of the discharge region D1, and the IPA is
not discharged from the organic solvent nozzle 103 when the IPA
supply region Su1 is positioned forward with respect to the
direction of progress of the discharge region D1. In this case,
actions and effects equivalent to those of the second preferred
embodiment are exhibited.
[0171] Also, with each of the first and second preferred
embodiments, the substrate W having the SiO.sub.2 63 disposed at
the front surface of the silicon substrate 61 (see FIG. 3) was
subject to processing. In place of the substrate W, a substrate W1,
described below, may be subject to the processing by the substrate
processing apparatus 1 or 101.
[0172] FIG. 13 is an enlarged sectional view of a vicinity of a
front surface of the substrate W1 to be processed by the substrate
processing apparatus 1 or 101.
[0173] The substrate W1 to be processed constitutes a base of a
semiconductor device having a multilayer wiring structure of copper
wirings and has an insulating film 71, constituted of a low-k (a
low dielectric constant material of lower relative dielectric
constant than SiO.sub.2, more preferably an ULK (ultra low-k)) film
formed at a surface layer portion. The insulating film 71 functions
as an insulating layer. Wiring trenches 72 are formed in the
insulating film 71 by digging from its front surface. A plurality
of the wiring trenches 72 are formed at fixed intervals in a
right/left direction in FIG. 13 with each extending in a direction
orthogonal to a paper surface of FIG. 13. A copper wiring 73 is
embedded in each wiring trench 72. A front surface of the copper
wiring 73 is made substantially flush with the front surface of the
insulating film 71.
[0174] FIGS. 14A to 14C are illustrative sectional views showing a
method for manufacturing the substrate W1 in order of process.
[0175] First, the insulating film 71 is formed on a semiconductor
substrate by a CVD method. Thereafter, the wiring trenches 72 are
formed by reactive ion etching in the surface layer portion of the
insulating film 71 as shown in FIG. 14A. Thereafter, a copper film
74 is formed on an upper surface of the insulating film 71 and
inside each wiring trench 72 as shown in FIG. 14B. As shown in FIG.
14B, the copper film 74 fills the interiors of the wiring trenches
72 completely and is also formed on the insulating film 71 outside
the wiring trenches 72.
[0176] Next, portions of the copper film 74 protruding outside the
respective wiring trenches are removed selectively by a CMP method.
A front surface of the copper film 74 is thereby made a flat
surface that is substantially flush with the front surface of the
insulating film 71 and the copper wirings 73 are formed as shown in
FIG. 14C (second preliminary preparation step).
[0177] The copper wirings 73 are formed by polishing the copper
film 74 by the CMP method and therefore copper polishing scraps
(slurry) 75 are present on the surface layer portion of the
substrate W1 immediately after manufacture. The substrate
processing apparatus 1 applies the cleaning processing to the
substrate W1 to remove the copper polishing scraps 75 from the
substrate W1.
[0178] Generally in such a cleaning processing, a chemical liquid,
such as hydrofluoric acid (HF), SC2 (hydrochloric acid/hydrogen
peroxide mixture), SPM (sulfuric acid/hydrogen peroxide mixture),
etc., is supplied to a substrate held by a spin chuck and
thereafter, water, such as pure water (de-ionized water), etc., is
supplied to rinse off the chemical liquid on the substrate with the
pure water (rinsing processing).
[0179] However, if pure water is supplied to the front surface of
the substrate W1 during the rinsing processing, the front surfaces
of the copper wirings 73 may become oxidized and this may influence
the performance of the semiconductor device after manufacture. Thus
with the substrate processing apparatus 1, IPA (organic solvent) is
used as a cleaning liquid to clean the front surface (upper
surface) of the substrate W1. IPA (organic solvent) is low in
oxidizing power with respect to copper. The front surface (upper
surface) of the substrate W1 can thus be cleaned satisfactorily
without excessively etching the front surfaces of the copper
wirings 73.
[0180] Also, the front surface of the insulating film 71 exhibits
high hydrophobicity (lyophobicity) because a low-k material has a
high contact angle. However, the front surface of the insulating
film 71 having high hydrophobicity can be wetted satisfactorily by
using IPA or other organic solvent, having a low surface tension,
as the cleaning liquid. An IPA liquid film that covers an entirety
of the upper surface of the substrate W1 can thereby be formed
satisfactorily.
[0181] In this case, if the front surface of the substrate W1
exhibits hydrophobicity, the IPA tends to dry non-uniformly on the
upper surface (front surface) of the substrate W1 in the drying
step (S7). There is thus a problem that particles tend to form on
the upper surface of the substrate W1 during the drying step (S7).
However, in the present preferred embodiment, the drying of the
substrate W1 is performed in a state where the upper surface of the
substrate W1 is covered by the annular gas streams from the gas
discharge nozzle 6 and therefore the formation of particles on the
upper surface of the substrate W1 can be suppressed.
[0182] Also in each of the first and second preferred embodiments,
a liquid film forming nozzle (not shown), constituted of a straight
nozzle capable of discharging a continuous stream, may be provided
separately from the double-fluid nozzle 16 and the IPA to be
supplied to the upper surface of the substrate Win the IPA liquid
film forming step (S3) may be discharged from the liquid film
forming nozzle. In this case, a second organic solvent supplying
unit includes the liquid film forming nozzle and an IPA supplying
apparatus supplying the IPA to the liquid film forming nozzle.
[0183] Also in each of the first and second preferred embodiments,
a post-supplying nozzle (not shown), constituted of a straight
nozzle capable of discharging a continuous stream, maybe provided
separately from the double-fluid nozzle 16 and the IPA to be
supplied to the upper surface of the substrate W in the IPA
post-supplying step (S5) may be discharged from the post-supplying
nozzle. In this case, a third organic solvent supplying unit
includes the post-supplying nozzle and an IPA supplying apparatus
supplying the IPA to the post-supplying nozzle.
[0184] In this case, the IPA supplying apparatus for the liquid
film forming nozzle and the IPA supplying apparatus for the
post-supplying nozzle maybe an apparatus in common or may be
separate, individual apparatuses. Further, a single nozzle may be
used in common as the liquid film forming nozzle (not shown) and
the post-supplying nozzle (not shown).
[0185] Also, although with each of the first and second preferred
embodiments, it was described that the rotation speed of the
substrate W in the IPA post-supplying step (S5) is a higher speed
than the rotation speed of the substrate Win the IPA liquid droplet
discharging step (S4), it may instead be approximately the same
speed as the rotation speed of the substrate W in the IPA liquid
droplet discharging step or may be a lower speed than the rotation
speed of the substrate W in that step.
[0186] Also, the IPA post-supplying step (S5) may be abolished.
That is, the drying step (S7) may be entered immediately after the
end of the IPA liquid droplet discharging step (S4). In this case,
the foreign matter removed in the IPA liquid droplet discharging
step (S4) is preferably eliminated from above the substrate W by
supplying a gas after the end of the IPA liquid droplet discharging
step (S4).
[0187] Also, although in each of the first and second preferred
embodiments, the changing of the guard facing the peripheral end
surface of the substrate W (S6) is executed after the end of the
IPA post-supplying step (S5) and before starting the drying step
(S7), it may be performed before the end of the IPA post-supplying
step (S5). For example, it may be performed before the start of IPA
post-supplying step (S5) after the end of the IPA liquid droplet
discharging step.
[0188] Also, the second guard 39 may be made to face the peripheral
end surface of the substrate W during the drying step (S7) without
performing the changing of the guard facing the peripheral end
surface of the substrate W (S6).
[0189] Also, although it was described that the gas discharge
nozzle 6 has the three gas discharge ports 44, 45, and 46, it does
not have to have all three gas discharge ports 44, 45, and 46 and
suffices to have at least one gas discharge port.
[0190] Also, in the first preferred embodiment, just one of either
the substrate W or the double-fluid nozzle 16 may be moved to make
the IPA liquid droplets collide against the entirety of the upper
surface of the substrate W. Specifically, the double-fluid nozzle
16 may be moved in a state where the substrate W is set still so
that the discharge region D1 passes across the entirety of the
upper surface of the substrate W. Also, the substrate W may be
moved in a state where the double-fluid nozzle 16 is set still so
that the discharge region D1 passes across the entirety of the
upper surface of the substrate W.
[0191] Also in each of the first and second preferred embodiments,
the movement locus of the discharge region D1 on the upper surface
of the substrate W may be a straight line. That is, the locus may
be a straight line extending along the upper surface of the
substrate W held by the spin chuck 3 and passing through a central
portion (preferably a center) of the upper surface of the substrate
W when viewed from a perpendicular direction perpendicular to the
upper surface of the substrate W.
[0192] Also, although with each of the first and second preferred
embodiments, it was described that the discharge region D1 is
arranged to be moved back and forth (half-scanned) between one
peripheral edge portion of the upper surface of the substrate W and
the upper surface central portion of the substrate W, it may
instead be arranged to be moved (full-scanned) between one
peripheral edge portion of the upper surface of the substrate W and
another peripheral edge portion at an opposite side of the one
peripheral edge portion across the substrate W upper surface
central portion.
[0193] Further, the gas discharge nozzle 6 may be abolished.
[0194] Also, although with each of the first and second preferred
embodiments, the two stage type processing cup 5 was described as
an example, the present invention is applicable to a substrate
processing apparatus including a processing cup of a multiple stage
type or a single cup type.
[0195] Also, although with each of the first and second preferred
embodiments, the externally-mixing type double-fluid nozzle 16,
which forms liquid droplets by mixing a gas and a liquid by making
these collide outside the nozzle body (at the outer cylinder 26
(see FIG. 6)), was described as an example of the double-fluid
nozzle 16, the present invention is also applicable to an
internally-mixing type double-fluid nozzle, which forms liquid
droplets by mixing a gas and a liquid inside the nozzle body.
[0196] Also, the organic solvent used in the present invention is
not restricted to IPA. The organic solvent includes at least one of
IPA, methanol, ethanol, HFE (hydrofluoroether), acetone, and
trans-1,2-dichloroethylene. Also, the organic solvent is not
restricted to a case of being constituted of a single component but
may also be a liquid mixed with another component. For example, it
may be a mixed liquid of IPA and acetone or a mixed liquid of IPA
and methanol.
[0197] Also, although with each of the first and second preferred
embodiments, the case where the substrate processing apparatus 1 or
101 is an apparatus arranged to process a disk-shaped substrate was
described, the substrate processing apparatus 1 or 101 may instead
be an apparatus arranged to process a polygonal substrate, such as
a substrate for liquid crystal display device, etc.
[0198] While preferred embodiments of the present invention have
been described in detail above, these are merely specific examples
used to clarify the technical contents of the present invention,
and the present invention should not be interpreted as being
limited only to these specific examples, and the spirit and scope
of the present invention shall be limited only by the appended
claims.
[0199] The present application corresponds to Japanese Patent
Application No. 2014-265537 filed on Dec. 26, 2014 in the Japan
Patent Office, and the entire disclosure of this application is
incorporated herein by reference.
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