U.S. patent application number 13/953002 was filed with the patent office on 2014-07-31 for semiconductor manufacturing apparatus and manufacturing method of semiconductor device.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Masahiro KIYOTOSHI, Tatsuhiko KOIDE, Yoshihiro OGAWA.
Application Number | 20140213064 13/953002 |
Document ID | / |
Family ID | 51223390 |
Filed Date | 2014-07-31 |
United States Patent
Application |
20140213064 |
Kind Code |
A1 |
KOIDE; Tatsuhiko ; et
al. |
July 31, 2014 |
SEMICONDUCTOR MANUFACTURING APPARATUS AND MANUFACTURING METHOD OF
SEMICONDUCTOR DEVICE
Abstract
A semiconductor manufacturing apparatus according to the present
embodiment comprises a chamber. A chemical-agent supply part is
configured to supply a water-repellent agent or an organic solvent
to a surface of a semiconductor substrate having been cleaned with
a cleaning liquid in the chamber. A spray part is configured to
spray a water-capture agent capturing water into an atmosphere in
the chamber.
Inventors: |
KOIDE; Tatsuhiko;
(Kuwana-Shi, JP) ; OGAWA; Yoshihiro;
(Yokkaichi-Shi, JP) ; KIYOTOSHI; Masahiro;
(Yokkaichi-Shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-Ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-Ku
JP
|
Family ID: |
51223390 |
Appl. No.: |
13/953002 |
Filed: |
July 29, 2013 |
Current U.S.
Class: |
438/758 ;
118/300; 118/313; 118/320; 118/50 |
Current CPC
Class: |
H01L 21/3086 20130101;
H01L 21/67034 20130101; H01L 27/11521 20130101; H01L 21/02057
20130101; H01L 21/0206 20130101; H01L 21/02068 20130101 |
Class at
Publication: |
438/758 ;
118/300; 118/50; 118/313; 118/320 |
International
Class: |
H01L 21/02 20060101
H01L021/02; H01L 21/67 20060101 H01L021/67 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 25, 2013 |
JP |
2013-011850 |
Claims
1. A semiconductor manufacturing apparatus comprising: a chamber; a
chemical-agent supply part supplying a water-repellent agent or an
organic solvent to a surface of a semiconductor substrate having
been cleaned with a cleaning liquid in the chamber; and a spray
part spraying a water-capture agent capturing water into an
atmosphere in the chamber.
2. The apparatus of claim 1, wherein the water-capture agent is
made of a material same as a material of the water-repellent
agent.
3. The apparatus of claim 1, wherein the water-repellent agent is a
silane coupling agent, and the organic solvent is isopropyl
alcohol.
4. The apparatus of claim 2, wherein the water-repellent agent is a
silane coupling agent, and the organic solvent is isopropyl
alcohol.
5. The apparatus of claim 1, wherein the spray part sprays the
water-capture agent into the atmosphere in the chamber either
simultaneously with or before a timing at which the chemical-liquid
supply part supplies the water-repellent agent or the organic
solvent to the surface of the semiconductor substrate.
6. The apparatus of claim 1, wherein the chemical-agent supply part
sprays the organic solvent to the surface of the semiconductor
substrate.
7. The apparatus of claim 1, wherein the chamber accommodates a
plurality of the semiconductor substrates, and the chemical-agent
supply part sprays the organic solvent to surfaces of the
semiconductor substrates.
8. The apparatus of claim 1, wherein the spray part is formed
integrally with the chemical-agent supply part.
9. The apparatus of claim 1, further comprising a mounting part
mounting the semiconductor substrate in the chamber, wherein the
mounting part rotates the semiconductor substrate in order to drain
off a liquid on the semiconductor substrate.
10. The apparatus of claim 1, comprising a vacuum device evacuating
air from interior of the chamber.
11. A manufacturing method of a semiconductor device for
manufacturing the semiconductor device using a semiconductor
manufacturing apparatus, which comprises a chamber, a
chemical-agent supply part supplying a water-repellent agent or an
organic solvent into the chamber, and a spray part spraying a
water-capture agent capturing water into the chamber, the method
comprising: arranging a semiconductor substrate having been cleaned
with a cleaning liquid in the chamber; spraying the water-capture
agent capturing water into an atmosphere in the chamber; and
supplying the water-repellent agent or the organic solvent to a
surface of the semiconductor substrate either simultaneously with
or after spraying of the water-capture agent.
12. The method of claim 11, wherein the water-capture agent is a
chemical liquid same as the water-repellent agent.
13. The method of claim 11, wherein the water-repellent agent is a
silane coupling agent, and the organic solvent is isopropyl
alcohol.
14. The method of claim 12, wherein the water-repellent agent is a
silane coupling agent, and the organic solvent is isopropyl
alcohol.
15. The method of claim 11, further comprising rinsing the surface
of the semiconductor substrate with deionized water after supplying
the water-repellent agent.
16. The method of claim 11, further comprising rotating the
semiconductor substrate in order to drain off a liquid on the
semiconductor substrate after supplying the water-repellent agent
or the organic solvent.
17. The method of claim 11, wherein supply of the organic solvent
is performed by allowing the chemical-agent supply part to spray
the water-repellent agent or the organic solvent to the surface of
the semiconductor substrate.
18. The method of claim 11, wherein the chamber accommodates a
plurality of the semiconductor substrates, and the chemical-agent
supply part sprays the organic solvent to surfaces of the
semiconductor substrates.
19. The method of claim 15, wherein the chamber accommodates a
plurality of the semiconductor substrates, and the chemical-agent
supply part sprays the organic solvent to surfaces of the
semiconductor substrates.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2013-011850, filed on Jan. 25, 2013, the entire contents of which
are incorporated herein by reference.
FIELD
[0002] The embodiments of the present invention relate to a
semiconductor manufacturing apparatus and a manufacturing method of
a semiconductor device.
BACKGROUND
[0003] Semiconductor device manufacturing processes include various
processes such as a lithographic process, an etching process, and
an ion implantation process. After the end of each process and
before shifting to the next process, a cleaning process and a
drying process are performed so as to remove impurities and
residues remaining on the surface of a semiconductor substrate to
clean the surface of the semiconductor substrate.
[0004] In recent years, following the downscaling of elements, the
aspect ratio of patterns on a semiconductor substrate has become
higher. At a higher aspect ratio, there occurs a problem that
capillary (surface tension) causes collapsing of the patterns on
the semiconductor substrate in the drying process.
[0005] To deal with such a problem, generally, there has been
proposed to use Isopropyl alcohol (IPA), which is an organic
solvent in the wet cleaning process. In a case of using the IPA,
the IPA displaces DIW (deionized water) on a semiconductor
substrate W and the surface of the semiconductor substrate is dried
with the IPA (subjected to an IPA drying treatment). However, when
much water is contained in the atmosphere in a chamber, there is a
probability that the IPA absorbs the water at a time of the IPA
drying treatment and that watermarks are formed on the surface of
the semiconductor substrate when the surface is dried.
[0006] Furthermore, there has been proposed a technique for making
the surface of the semiconductor substrate water repellent and
lowering the capillary that acts between the patterns and a
chemical liquid or DIW. However, a water-repellent agent used for
making the surface of the semiconductor substrate water repellent
is often deactivated after reacting to the water. For example, it
often occurs in a cleaning device that the water-repellent agent is
deactivated after reacting to the water in a chamber. If such
deactivation of the water-repellent agent occurs, the
water-repellent agent is unable to make the surface of the
semiconductor substrate water repellent and to suppress collapsing
of the patterns on the semiconductor substrate resulting from the
capillary (surface tension).
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows an example of a configuration of a surface
treatment apparatus 10 for a semiconductor substrate according to a
first embodiment;
[0008] FIG. 2 shows a contact angle .theta. of a liquid on patterns
4 on the semiconductor substrate W;
[0009] FIGS. 3A to 3D are cross-sectional views showing a
manufacturing method of a NAND flash memory according to the first
embodiment;
[0010] FIG. 4 is a flowchart showing the surface treatment method
according to the first embodiment;
[0011] FIG. 5 is a flowchart showing the surface treatment method
according to the second embodiment;
[0012] FIGS. 6A and 6B show an example of a configuration of a
surface treatment apparatus 30 for semiconductor substrates
according to a third embodiment; and
[0013] FIG. 7 is a flowchart showing a surface treatment method
according to the third embodiment.
DETAILED DESCRIPTION
[0014] Embodiments will now be explained with reference to the
accompanying drawings. The present invention is not limited to the
embodiments.
[0015] A semiconductor manufacturing apparatus according to the
present embodiment comprises a chamber. A chemical-agent supply
part is configured to supply a water-repellent agent or an organic
solvent to a surface of a semiconductor substrate having been
cleaned with a cleaning liquid in the chamber. A spray part is
configured to spray a water-capture agent capturing water into an
atmosphere in the chamber.
First Embodiment
[0016] FIG. 1 shows an example of a configuration of a surface
treatment apparatus 10 for a semiconductor substrate according to a
first embodiment. The surface treatment apparatus 10 includes a
mounting unit 100 on which a semiconductor substrate (a wafer) W is
mounted, a liquid supply unit 200 that supplies liquids, a chamber
300 that hermetically seals the semiconductor substrate W, and a
spray unit 400 that sprays a water-capture agent 2.
[0017] The mounting unit 100 includes a rotary shaft 102, a spin
base 103, and chuck pins 104. The rotary shaft 102 extends
substantially in a vertical direction and the disk-like spin base
103 is attached on an upper end of the rotary shaft 102. A motor
(not shown) can rotate the rotary shaft 102 and the spin base
103.
[0018] The chuck pins 104 are provided on peripheral edges of the
spin base 103, respectively. The chuck pins 104 fix the
semiconductor substrate W on the spin base 103 by putting the
semiconductor substrate W between the chuck pins 104. The mounting
unit 100 can rotate the semiconductor substrate W while keeping the
semiconductor substrate W substantially horizontally.
[0019] The liquid supply unit 200 discharges a liquid 1 to a
surface of the semiconductor substrate W near a rotation center
thereof. By allowing the mounting unit 100 to rotate the
semiconductor substrate W, the discharged liquid 1 can spread in a
radial direction of the semiconductor substrate W and can be
applied on the surface of the semiconductor substrate W.
[0020] Furthermore, by allowing the mounting unit 100 to rotate the
semiconductor substrate W, the liquid 1 on the semiconductor
substrate W can be drained off and the semiconductor substrate W
can be spin-dried. The excessive liquid 1 spattering in the radial
direction of the semiconductor substrate W is discharged via a
waste liquid pipe 105. For example, the liquid 1 is a cleaning
liquid, a water-repellent agent, DIW (deionized water) or an
organic solvent.
[0021] The liquid supply unit 200 includes a first chemical-liquid
supply unit 210 that supplies the cleaning liquid for cleaning the
semiconductor substrate W to the surface of the semiconductor
substrate W, a second chemical-liquid supply unit 220 serving as a
chemical-agent supply unit that supplies the water-repellent agent
for forming a water-repellent protection film to the surface of the
semiconductor substrate W, and a DIW supply unit 230 that supplies
the DIW to the surface of the semiconductor substrate W.
[0022] The cleaning liquid supplied from the first chemical-liquid
supply unit 210 passes through a supply pipe 212 and is discharged
from a nozzle 211. For example, the cleaning liquid is an SC1
liquid (Ammonia-Hydrogen Peroxide mixture) or an SPM liquid
(Sulfuric acid-Hydrogen Peroxide Mixture) and is a chemical liquid
used for removing etching residues and the like.
[0023] The water-repellent agent supplied from the second
chemical-liquid supply unit 220 passes through a supply pipe 222
and is discharged from a nozzle 221. The water-repellent agent is a
chemical liquid for forming the water-repellent protection film on
surfaces of patterns formed on the semiconductor substrate W and
making the surfaces of the patterns water repellent. For example,
the water-repellent agent is a silane coupling agent. The silane
coupling agent contains hydrolytic groups having an affinity and a
reactivity to inorganic materials and organic functional groups
chemically bonding organic materials in molecules. Examples of the
silane coupling agent include hexamethyldisilazane (HMDS), tetra
methylsilyldimethyla mine (TMSDMA), and trimethylsilyldimethylamine
(TMSDEA).
[0024] The DIW supplied from the DIW supply unit 230 passes through
a supply pipe 232 and is discharged from a nozzle 231. The DIW is
used to rinse away a chemical liquid on the semiconductor substrate
W.
[0025] The spray unit 400 sprays the water-capture agent 2 into the
chamber 300 so as to capture water contained in an atmosphere in
the chamber 300. Although not limited to a specific one, the
water-capture agent 2 suffices to be a chemical agent that easily
reacts to the water and that does not react to the chamber 300, the
semiconductor substrate W, and the water-repellent agent. For
example, the silane coupling agent serving as the water-repellent
agent can be used as the water-capture agent 2. Examples of the
silane coupling agent include HMDS, TMSDMA, and TMSDEA mentioned
above.
[0026] A material same as that of the water-repellent agent can be
used as that of the water-capture agent 2. However, when any one of
HMDS, TMSDMA, and TMSDEA is used as the water-repellent agent, any
of HMDS, TMSDMA, and TMSDEA can be used as the water-capture agent
2. In this case, a different material from that of the
water-repellent agent can be used as the material of the
water-capture agent 2.
[0027] The spray unit 400 evaporates the water-repellent agent 2
and sprays the evaporated water-repellent agent 2 into the chamber
300. The water-repellent agent 2 thereby reacts to the water in the
atmosphere in the chamber 300 and captures the water. In other
words, the water-capture agent 2 absorbs the water in the chamber
300.
[0028] The spray unit 400 sprays the evaporated water-capture agent
2 into the atmosphere in the chamber 300 either simultaneously with
or before a timing at which the second chemical-liquid supply unit
220 supplies the water-repellent agent to the surface of the
semiconductor substrate W. The spray unit 400 can continue spraying
the water-repellent agent into the chamber 300 in parallel to the
supply of the water-repellent agent while the second
chemical-liquid supply unit 220 is supplying the water-repellent
agent. The water-capture agent 2 can thereby sufficiently capture
the water in the chamber 300 before the water-repellent agent is
supplied to the semiconductor substrate W. Therefore, it is
possible to suppress the water-repellent agent from reacting to the
water in the atmosphere in the chamber 300 and being deactivated.
The spray unit 400 can spray the water-capture agent 2
continuously, instantaneously or intermittently.
[0029] The surface treatment apparatus 10 can include a vacuum
device (not shown) that evacuates the air from the interior of the
chamber 300. In this case, the vacuum device discharges the water
in the chamber 300 to outside to some extent and the spray unit 400
sprays the water-repellent agent into the chamber 300 in a vacuum.
It is thereby possible to remove the water in the chamber 300 more
efficiently.
[0030] Furthermore, the surface treatment apparatus 10 can include
an excimer UV (ultraviolet) irradiation unit (not shown). The
excimer UV irradiation unit can selectively remove the
water-repellent protection film by irradiating UV light on the
semiconductor substrate W.
[0031] FIG. 2 shows a contact angle .theta. of a liquid on patterns
4 on the semiconductor substrate W. When an aspect ratio of the
patterns 4 becomes higher by downscaling the patterns 4, a liquid 5
enters between adjacent patterns 4 by the capillary of the liquid
5. In this case, power P with which the liquid 5 acts on the
patterns 4 is represented by the following Equation (1).
P=2.times..gamma..times.cos .theta.H/SPACE (1)
In this equation, SPACE denotes a space between adjacent patterns
4. H denotes the height of each pattern 4. .gamma. denotes the
surface tension of the liquid 5.
[0032] It is understood that as the contact angle .theta. is closer
to 90.degree., then cos .theta. becomes closer to zero and the
power P acting on the patterns 4 becomes lower. The fact that the
contact angle .theta. is closer to 90.degree. means that the
surface of the semiconductor substrate W (the surface of each
pattern 4) is made water repellent. Therefore, pattern collapsing
can be suppressed by making the surface of the semiconductor
substrate W water repellent.
[0033] To make the surface of the semiconductor substrate W water
repellent, the water-repellent protection film is formed on the
surface of the semiconductor substrate W using the water-repellent
agent such as the silane coupling agent (a sililation treatment).
However, when the water is present in the chamber 300, the silane
coupling agent has a hydrolytic reaction to the water in the
chamber 300 and loses a water-repellent function. That is, the
silane coupling agent is deactivated. For example, when the silane
coupling agent is supplied to the rotation center of the
semiconductor substrate W shown in FIG. 1, it is likely that the
silane coupling agent reacts to the water and is deactivated before
the silane coupling agent spreads through peripheral edges of the
semiconductor substrate W. In this case, the water-repellent
protection film is formed on the patterns 4 near a central portion
of the semiconductor substrate W but not on the patterns 4 near the
peripheral edges of the semiconductor substrate W.
[0034] On the other hand, according to the first embodiment, the
spray unit 400 sprays the evaporated water-capture agent 2 into the
chamber 300 at or before a time of supplying the water-repellent
agent. Because the water-capture agent 2 reacts to the water in the
chamber 300, a water amount in the chamber 300 greatly decreases at
the time of supplying the water-repellent agent. This can suppress
deactivation of the water-repellent agent. As a result, it is
possible to ensure making the surface of the semiconductor
substrate W and the surfaces of the patterns 4 water repellent, to
make the contact angle .theta. closer to 90.degree., and to
suppress collapsing of the patterns 4 on the semiconductor
substrate W.
[0035] FIGS. 3A to 3D are cross-sectional views showing a
manufacturing method of a NAND flash memory according to the first
embodiment. FIG. 4 is a flowchart showing a surface treatment
method according to the first embodiment.
[0036] The surface treatment method according to the first
embodiment is applied to, for example, processes of cleaning and
drying the semiconductor substrate W in processing of charge
accumulation layers CA (floating gates, for example) of the NAND
flash memory. Although a sidewall transfer process is often used to
process the charge accumulation layers CA, an ordinary resist
transfer process is used here for the brevity of descriptions.
Needless to mention, the first embodiment is also applicable to
cleaning and drying processes in the sidewall transfer process.
[0037] First, a gate dielectric film 20 is formed on the
semiconductor substrate W. The gate dielectric film 20 is formed by
thermally oxidizing the semiconductor substrate W. The thickness of
the gate dielectric film 20 is about 5 nm, for example.
[0038] Next, a polysilicon layer 30 is formed on the gate
dielectric film 20. The polysilicon layer 30 is used as the
material of the charge accumulation layers CA. The thickness of the
polysilicon layer 30 is about 100 nm, for example.
[0039] Next, a silicon nitride film 40 is formed on the polysilicon
layer 30. The silicon nitride film 40 functions as an etching
stopper. The thickness of the silicon nitride film 40 is about 100
nm, for example.
[0040] Next, a silicon oxide film 50 is formed on the silicon
nitride film 40. The silicon oxide film 50 is used as hard masks HM
for processing the polysilicon layer 30 (the charge accumulation
layers CA) or the like. The thickness of the silicon oxide film 50
is 250 nm, for example.
[0041] Next, a sacrificial film 60 is formed on the silicon oxide
film 50. It suffices that the sacrificial film 60 is made of a
material that can selectively etch the silicon oxide film 50. For
example, a silicon nitride film, a polysilicon film or the like can
be used as the sacrificial film 60. The thickness of the
sacrificial film 60 is 100 nm, for example.
[0042] Next, using a lithographic technique, a resist layer 70 is
formed on the sacrificial film 60. The resist layer 70 is patterned
to process the sacrificial film 60 into patterns of the charge
accumulation layers CA. For example, the resist layer 70 is formed
into line-and-space patterns. The line width and space width of the
resist layer 70 are both about 20 nm, for example. The structure
shown in FIG. 3A is obtained in this manner.
[0043] Next, using the resist layer 70 as a mask, the sacrificial
film 60 is processed by a RIE (Reactive Ion Etching) method.
[0044] After removing the resist layer 70 using, for example, a SPM
liquid (Sulfuric acid-Hydrogen Peroxide Mixture), the silicon oxide
film 50 is processed by the RIE method with the sacrificial film 60
used as a mask. Etching of the silicon oxide film 50 stops on the
silicon nitride film 40. The structure of the hard masks HM is
thereby obtained as shown in FIG. 3B. At this time, an aspect ratio
of each hard mask HM is about 10. The sacrificial film 60 can be
removed at the time of etching the silicon oxide film 50.
[0045] When the sidewall transfer process is used, the sacrificial
film 60 is used as a core of sidewall masks (not shown). For
example, after narrowing the width of the sacrificial film 60 by
slimming, a sidewall film (not shown) is deposited on the
sacrificial film 60. Thereafter, the sidewall film is etched back,
thereby leaving the sidewall film on both side surfaces of the
sacrificial film 60 as the sidewall masks. The sidewall masks are
formed by removing the sacrificial film 60. When the silicon oxide
film 50 is etched using the sidewall masks as a mask, it is
possible to form the hard masks HM each having a smaller line width
and a smaller space width than those of a minimum feature size F
(Feature size) that can be formed by the lithographic technique. In
this way, the hard masks HM can be alternatively processed using
the sidewall transfer process. Needless to mention, the hard masks
HM can be processed into smaller patterns by repeating the sidewall
transfer process.
[0046] Next, the semiconductor substrate W is cleaned so as to
remove etching residues generated in the etching of the silicon
oxide film 50. For example, the semiconductor substrate W is
subjected to a cleaning treatment using the SPM liquid or the SC1
liquid.
[0047] After the cleaning treatment, the chemical liquid is rinsed
away with the DIW. At this time, the DIW enters between the
adjacent hard masks HM. When the surface of the semiconductor
substrate W is dried in a state where the DIW is present between
the hard masks HM, the capillary or surface tension (the power P
represented by the Equation (1) mentioned above) of the DIW
possibly causes collapsing of the hard masks HM.
[0048] To prevent this possibility, the surface treatment apparatus
10 according to the first embodiment forms a water-repellent
protection film R on the surface of the semiconductor substrate W
and those of the patterns after the cleaning treatment. A method of
forming the water-repellent protection film R is described below
with reference to FIG. 4.
[0049] FIG. 4 is a flowchart showing the surface treatment method
according to the first embodiment. As shown in FIG. 4, after
mounting the semiconductor substrate W on the mounting unit 10
(S10), the mounting unit 10 rotates the semiconductor substrate W.
The first chemical-liquid supply unit 210 supplies the cleaning
liquid for cleaning the semiconductor substrate W to the surface of
the semiconductor substrate W arranged in the chamber 300. The
cleaning liquid spreads throughout the surface of the semiconductor
substrate W by rotation of the semiconductor substrate W. The
etching residues are thereby removed (S20: cleaning treatment).
After cleaning the semiconductor substrate W, the DIW supply unit
230 supplies the DIW to the semiconductor substrate W. The DIW
spreads throughout the surface of the semiconductor substrate W by
the rotation of the semiconductor substrate W. The cleaning liquid
on the surface of the semiconductor substrate W is thereby rinsed
away with the DIW (S30: DIW rinse treatment).
[0050] Next, the spray unit 400 evaporates the water-capture agent
2 and sprays the evaporated water-capture agent 2 into the chamber
300. The water-capture agent 2 thereby captures the water in the
atmosphere in the chamber 300 (S40: water capture treatment). For
example, HMDS serving as the silane coupling agent can be used as
the water-capture agent 2. In this case, HMDS reacts to the water
and changes to silanol. Furthermore, the bimolecular silanol is
condensed into inactive siloxane. In this way, because the
water-capture agent 2 reacts to the water and changes to the
inactive substance, the water in the chamber 300 can be
reduced.
[0051] Simultaneously with or after spraying of the water-capture
agent 2, the second chemical-liquid supply unit 220 supplies the
water-repellent agent to the surface of the semiconductor substrate
W (S50: sililation treatment). The water-repellent agent spreads
throughout the surface of the semiconductor substrate W by the
rotation of the semiconductor substrate W. For example, the
water-repellent agent is TMSDMA serving as the silane coupling
agent. At this time, the water-repellent agent can spread
throughout the surface of the semiconductor substrate W without
being deactivated because the water is hardly present in the
chamber 300. The water-repellent protection film R is thereby
formed on the entire surfaces of the patterns on the semiconductor
substrate W.
[0052] When the patterns on the semiconductor substrate W are
formed of a silicon-based film such as the silicon nitride film or
the polysilicon film, sufficient water repellency is not often
ensured because of an insufficient sililation reaction even after
the sililation treatment using the silane coupling agent. In this
case, before Step S50, the surfaces of the silicon-based patterns
are changed to silicon oxide-based chemical oxide films using
another chemical liquid. When the sililation treatment is
subsequently performed, it is possible to improve water repellency
after the sililation treatment.
[0053] Many residues are generated after the etching by the RIE
method. It is difficult to form the water-repellent protection film
in a state where many residues remain. Therefore, it is effective
to remove the residues by the cleaning treatment so as to form the
water-repellent protection film. In addition, plasma damages are
accumulated on the surfaces of the patterns by the RIE method and
dangling bonds are generated. When a reforming treatment is
performed using a cleaning liquid having an oxidation effect, the
dangling bonds terminate at OH groups. If many OH groups are
present, the sililation reaction probability increases, which
facilitates forming the water-repellent protection film. This can
further improve the water repellency. Even when the patterns are
formed of the silicon oxide film, identical effects can be
obtained. When the cleaning liquid has also a reforming effect (an
oxidation effect), it is possible to simultaneously perform the
cleaning treatment and the reforming treatment using the single
cleaning liquid.
[0054] Next, the DIW supply unit 230 supplies the DIW on the
semiconductor substrate W and rinses again the surface of the
semiconductor substrate W (S60: DIW rinse treatment). The DIW
spreads throughout the surface of the semiconductor substrate W by
the rotation of the semiconductor substrate W. The mounting unit
100 accelerates a rotational speed for rotating the semiconductor
substrate W to a predetermined speed, thereby draining off and
drying the DIW on the surface of the semiconductor substrate W
(S70: spin drying treatment). At this time, the DIW can be easily
removed from the semiconductor substrate W because surfaces of the
hard masks HM are already in a water repellent state. Furthermore,
even if the DIW is present between the adjacent hard masks HM, the
capillary or surface tension of the DIW is very low because the
surfaces of the hard masks HM are already in the water repellent
state. Therefore, it is difficult for the hard masks HM to
collapse.
[0055] Next, using the hard masks HM as a mask, the polysilicon
layer 30, the gate dielectric film 20, and the semiconductor
substrate W are processed by the RIE method. The structure shown in
FIG. 3D is thereby obtained.
[0056] Thereafter, STI (Shallow Trench Isolation), IPD (Inter Poly
Dielectric), control gates, and the like are formed using
well-known processes, thereby completing the NAND flash memory.
[0057] As described above, according to the first embodiment, the
water-capture agent 2 is sprayed into the atmosphere in the chamber
300 either simultaneously with or before the timing of supplying
the water-repellent agent to the surface of the semiconductor
substrate W. The water-capture agent 2 thereby captures the water
in the chamber 300 before the water-repellent agent is supplied to
the semiconductor substrate W. Therefore, it is possible to
suppress the water-repellent agent from reacting to the water in
the atmosphere in the chamber 300 and being deactivated. As a
result, according to the first embodiment, it is possible to ensure
making the surface of the semiconductor substrate W water repellent
and to suppress collapsing of the patterns on the semiconductor
substrate W.
Second Embodiment
[0058] The surface treatment apparatus 10 and a surface treatment
method according to a second embodiment differ from those according
to the first embodiment in the use of an organic solvent in place
of the water-repellent agent. Therefore, the second chemical-liquid
supply unit 220 shown in FIG. 1 supplies not the water-repellent
agent but the organic solvent to the semiconductor substrate W. In
this case, it is unnecessary to perform the DIW rinse treatment in
Step S60 shown in FIG. 4. Other configurations and processes of the
second embodiment can be identical to those of the first
embodiment. Because configurations of the surface treatment
apparatus according to the second embodiment are basically
identical to those of the surface treatment apparatus 10 according
to the first embodiment shown in FIG. 1, detailed explanations
thereof will be omitted.
[0059] In the second embodiment, the organic solvent is IPA, for
example. The water-repellent agent can be used as the water-capture
agent 2 similarly to the water-capture agent 2 in the first
embodiment. The organic solvent is used in place of the
water-repellent agent. This is because most of organic solvents
have properties of low surface tension and high volatility. Because
of the low surface tension, it is possible to suppress collapsing
of the patterns on the semiconductor substrate W as described
above. Because of the high volatility, the drying treatment can be
performed swiftly and easily. Therefore, the liquid supplied from
the second chemical-liquid supply unit 220 suffices to be a liquid
low in surface tension without being specifically limited to the
organic solvent. The liquid having the high volatility as well as
the low surface tension is preferable because the high volatility
is advantageous in the drying treatment.
[0060] The spray unit 400 sprays the water-capture agent 2 into the
atmosphere in the chamber 300 either simultaneously with or before
a timing at which the second chemical-liquid supply unit 220
supplies the organic solvent to the surface of the semiconductor
substrate W. The spray unit 400 can continue spraying the
water-repellent agent 2 into the chamber 300 in parallel to the
supply of the organic solvent while the second chemical-liquid
supply unit 220 is supplying the organic solvent. The water-capture
agent 2 can thereby capture the water in the chamber 300 before the
organic solvent is supplied to the semiconductor substrate W.
Therefore, the organic solvent is suppressed from absorbing the
water in the atmosphere in the chamber 300 and the organic solvent
displaces the water present on the surfaces of the patterns on the
semiconductor substrate W. The spray unit 400 can spray the
water-capture agent 2 continuously, instantaneously or
intermittently.
[0061] FIG. 5 is a flowchart showing the surface treatment method
according to the second embodiment. Because Steps S10 to S40 in
FIG. 5 are identical to Steps S10 to S40 in FIG. 4, detailed
explanations thereof will be omitted.
[0062] Simultaneously with or after spraying of the water-capture
agent 2, the second chemical-liquid supply unit 220 supplies the
organic solvent (IPA, for example) to the surface of the
semiconductor substrate W (S51). At this time, the organic solvent
spreads throughout the surface of the semiconductor substrate W
without absorbing the water because the water is hardly present in
the chamber 300. The organic solvent thereby displaces the water
present on the surfaces of the patterns on the semiconductor
substrate W. Therefore, it is possible to suppress watermarks from
being formed on the surface of the semiconductor substrate W at the
time of an IPA drying treatment.
[0063] Thereafter, the semiconductor substrate W is dried by the
spin drying treatment. Step S70 shown in FIG. 5 is the same as Step
S70 shown in FIG. 4.
[0064] Generally, when the IPA that is the organic solvent is used
in the cleaning process, the IPA displaces the DIW on the
semiconductor substrate W and dries the surface of the
semiconductor substrate W (the IPA drying treatment). However, if
much water is contained in the atmosphere in the chamber 300, there
is a probability that the IPA absorbs the water at the time of the
IPD drying treatment and that watermarks are formed on the surface
of the semiconductor substrate W when the surface is dried.
[0065] According to the second embodiment, the water-capture agent
2 is sprayed into the atmosphere in the chamber 300 either
simultaneously with or before the timing of supplying the organic
solvent to the surface of the semiconductor substrate W. The
water-capture agent 2 can thereby capture the water in the chamber
300 before the organic solvent is supplied to the semiconductor
substrate W. Therefore, the organic solvent can displace the water
on the surface of the semiconductor substrate W and those of the
patterns without absorbing the water in the chamber 300. If the IPA
displaces the water on the surface of the semiconductor substrate W
and those of the patterns, then wettability of the liquid 5 on the
surface of the semiconductor substrate W improves and cos .theta.
in the Equation (1) becomes larger, but .gamma. in the Equation (1)
becomes smaller. The power P thereby becomes lower as a whole. As a
result, it is possible to suppress collapsing of the patterns on
the semiconductor substrate W and to suppress the watermarks from
being formed on the semiconductor substrate W.
[0066] The first and second embodiments are not limited to the
patterns of the hard masks HM described above but applicable to
arbitrary patterns having a high aspect ratio. Furthermore, the
first and second embodiments are not limited to the patterns of the
hard masks HM in the process of cleaning the semiconductor
substrate W but applicable to resist patterns after development in
a lithographic process.
[0067] Furthermore, while the spray unit 400 shown in FIG. 1 can be
arranged in an upper portion of the chamber 300 in the first
embodiment, the spray unit 400 can be formed integrally with the
second chemical-liquid supply unit 220. When the material of the
water-capture agent 2 is the same as that of the water-repellent
agent, a common pipe to the spray unit 400 and the second
chemical-liquid supply unit 220 can be used by forming the spray
unit 400 and the second chemical-liquid supply unit 220 integrally.
This makes it relatively easier to pull out the pipe.
[0068] The first and second embodiments can be combined. In this
case, the surface treatment apparatus 10 includes both a
water-repellent-agent supply unit that supplies the water-repellent
agent and an IPA supply unit that supplies the IPA. For example,
after cleaning the semiconductor substrate W, the surface treatment
apparatus 10 rinses the cleaning liquid with the DIW and supplies
the IPA to the semiconductor substrate W by the method according to
the second embodiment. The IPA thereby displaces the water on the
semiconductor substrate W. The surface treatment apparatus 10
supplies the water-repellent agent to the semiconductor substrate W
by the method according to the first embodiment. The
water-repellent protection film is thereby formed on the surface of
the semiconductor substrate W (the surface of each pattern). The
surface treatment apparatus 10 supplies the IPA again to the
semiconductor substrate W by the method according to the second
embodiment. The IPA thereby displaces the water-repellent agent.
Furthermore, the water treatment apparatus 10 supplies the DIW
again to the semiconductor substrate W. The DIW thereby displaces
the IPA. Thereafter, the water treatment apparatus 10 dries the
semiconductor substrate W by spinning the semiconductor substrate
W. At this time, the semiconductor substrate W can be dried without
collapsing of the patterns on the semiconductor substrate W because
the surfaces of the patterns on the semiconductor substrate W are
in a water repellent state.
Third Embodiment
[0069] FIGS. 6A and 6B show an example of a configuration of a
surface treatment apparatus 30 for semiconductor substrates
according to a third embodiment. In the first and second
embodiments, the surface treatment apparatus 10 is a single-wafer
surface treatment apparatus for processing semiconductor substrates
W one by one. On the other hand, the surface treatment apparatus 30
according to the third embodiment is a batch surface treatment
apparatus for batch-processing a plurality of semiconductor
substrates W. Therefore, the chamber 300 accommodates a plurality
of semiconductor substrates W (semiconductor substrates W
corresponding to two lots, for example) at a time. The interior of
the chamber 300 can be kept in a vacuum when processing the
semiconductor substrates W.
[0070] The chemical-liquid supply unit 220 sprays an evaporated
organic solvent (IPA, for example) 3 into the chamber 300 so as to
supply the organic solvent 3 to the semiconductor substrates W. The
organic solvent 3, which is evaporated, can spread through surfaces
of the semiconductor substrates W. The spray unit 400 sprays the
evaporated water-capture agent 2 into the chamber 300. The
water-capture agent 2, which is evaporated similarly, can spread
through the surfaces of the semiconductor substrates W. Forms of
the chemical-liquid supply unit 220 and the spray unit 400 are not
limited to specific ones, so that either nozzle-like units shown in
FIGS. 6A and 6B or the box-like units shown in FIG. 1 can be used
as the chemical-liquid supply unit 220 and the spray unit 400.
[0071] For example, the IPA can be used as the organic solvent 3
similarly to the organic solvent in the second embodiment. Any of
the water-repellent agents can be used as the water-capture agent 2
similarly to the water-capture agent 2 in the first embodiment.
[0072] A DIW reservoir 500 is a reservoir that stores therein the
DIW and in which a batch of semiconductor substrates W can be
immersed in the DIW. The DIW in the DIW reservoir 500 is
circulated, filtered so as to keep a lightly doped state after use,
and reused.
[0073] FIG. 7 is a flowchart showing a surface treatment method
according to the third embodiment. The surface treatment method
according to the third embodiment is described with reference to
FIGS. 6A, 6B, and 7.
[0074] First, the semiconductor substrates W are subjected to the
cleaning treatment using the cleaning liquid (S22). The cleaning
treatment can be performed either outside or inside of the chamber
300. In the third embodiment, it is assumed that the semiconductor
substrates W are cleaned outside of the chamber 300 and that the
semiconductor substrates W are arranged in the chamber 300 after
the cleaning liquid is rinsed away with the DIW.
[0075] The cleaning treatment can be performed either on every
semiconductor substrate W or collectively on a plurality of
semiconductor substrates W as a batch process. When the cleaning
treatment is performed as the batch process, it suffices to store
the cleaning liquid in a reservoir (not shown) similar to the DIW
reservoir 500 and to immerse the semiconductor substrates W in the
reservoir. A case of performing the cleaning treatment inside of
the chamber 300 is described later in a modification of the third
embodiment.
[0076] As described above, after the cleaning treatment, the
cleaning liquid on the semiconductor substrates W is rinsed away
with the DIW (S32). As shown in FIG. 6A, the semiconductor
substrates W are introduced into the chamber 300 in a vacuum, the
semiconductor substrates W are immersed in the DIW reservoir 500,
and surfaces of the semiconductor substrates W are rinsed with the
DIW (S42). Before or after arranging the semiconductor substrates W
in the chamber 300, the spray unit 400 evaporates the water-capture
agent 2 and sprays the evaporated water-capture agent 2 into the
chamber 300. The water-capture agent 2 thereby captures the water
in the atmosphere in the chamber 300 (S52).
[0077] Simultaneously with or after spraying of the water-capture
agent 2, the chemical-liquid supply unit 220 supplies the
evaporated organic solvent 3 to the surfaces of the semiconductor
substrates W (S62). The organic solvent 3 can easily spread through
the surfaces of the semiconductor substrates W because the organic
solvent 3 is sprayed in an evaporated state. At this time, the
organic solvent 3 can spread throughout the surfaces of the
semiconductor substrates W without absorbing the water because the
water is hardly present in the chamber 300. The organic solvent
(IPA, for example) 3 can thereby easily displace the water on the
entire surfaces of the semiconductor substrates W when the
chemical-liquid supply unit 220 supplies the organic solvent 3.
[0078] Next, the semiconductor substrates W are pulled out of the
DIW reservoir 500 and dried (S72). At this time, the organic
solvent 3 displaces the water on the surfaces of the hard masks HM.
Therefore, it is easy to remove the DIW from the semiconductor
substrates W and it is difficult for the patterns of the hard masks
HM to collapse. It is also possible to suppress watermarks from
being formed on the surfaces of the semiconductor substrates W.
[0079] Other processes in the third embodiment can be performed
similarly to the corresponding processes in the second embodiment.
According to the third embodiment, it is thereby possible to
perform the IPA drying treatment collectively on a batch of the
semiconductor substrates W. The third embodiment can achieve
effects identical to those of the second embodiment.
Modification of Third Embodiment
[0080] In the third embodiment, the cleaning treatment for cleaning
the semiconductor substrates W (S22 in FIG. 7) and the DIW rinse
treatment for rinsing away the cleaning liquid with the DIW (S32 in
FIG. 7) are performed outside of the chamber 300. In the
modification of the third embodiment, the cleaning treatment for
cleaning the semiconductor substrates W and the rinse treatment for
rinsing away the cleaning liquid with the DIW are performed inside
of the chamber 300. In this case, it suffices to initially store
the cleaning liquid in the treatment reservoir 500 and to replace
the cleaning liquid in the treatment reservoir 500 with the DIW
after performing the cleaning treatment. At this time, the
semiconductor substrates W can be kept stored in the treatment
reservoir 500. Alternatively, the semiconductor substrates W can be
temporarily pulled out of the treatment reservoir 500 and, after
replacing the cleaning liquid in the treatment reservoir 500 with
the DIW, the semiconductor substrates W can be stored again in the
treatment reservoir 500 and the cleaning liquid on the
semiconductor substrates W can be rinsed with the DIW.
[0081] After rinsing the cleaning liquid with the DIW, the
semiconductor substrates W are pulled out of the treatment
reservoir 500, and Steps S42 to S72 shown in FIG. 7 are performed.
According to this modification, the cleaning treatment and the
drying treatment can be performed for every batch of the
semiconductor substrates W. This modification can also achieve
effects identical to those of the third embodiment.
[0082] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
methods and systems described herein may be embodied in a variety
of other forms; furthermore, various omissions, substitutions and
changes in the form of the methods and systems described herein may
be made without departing from the spirit of the inventions. The
accompanying claims and their equivalents are intended to cover
such forms or modifications as would fall within the scope and
spirit of the inventions.
* * * * *