U.S. patent application number 09/800537 was filed with the patent office on 2001-09-13 for substrate dryer.
This patent application is currently assigned to Dainippon Screen Mfg. Co., Ltd.. Invention is credited to Kimura, Masahiro.
Application Number | 20010020337 09/800537 |
Document ID | / |
Family ID | 27342608 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020337 |
Kind Code |
A1 |
Kimura, Masahiro |
September 13, 2001 |
Substrate dryer
Abstract
A substrate dryer causing no water mark on a substrate having a
refined.multidot.complicated structure and capable of suppressing
increase of a cost required for a drying treatment is provided.
Drying gas of low-molecular silicone generated in a drying gas
generation part is heated by a heater and thereafter supplied from
a drying gas supply nozzle. The drying gas is supplied to the main
surface of a substrate being pulled up from de-ionized water stored
in a cleaning bath as a stream. Silicone contained in the drying
gas is condensed on the surface of the substrate, substitutes for
moisture, and thereafter vaporizes. Silicone is excellent in
permeability.multidot.dryability, and hence can suppress formation
of a water mark also on a substrate having a
refined.multidot.complicated structure. Further, silicone applies
no load to the environment, and hence increase of a cost required
for the drying treatment can be suppressed without requiring
specific treatment for disposal.
Inventors: |
Kimura, Masahiro; (Kyoto,
JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Dainippon Screen Mfg. Co.,
Ltd.
|
Family ID: |
27342608 |
Appl. No.: |
09/800537 |
Filed: |
March 7, 2001 |
Current U.S.
Class: |
34/72 |
Current CPC
Class: |
H01L 21/67034
20130101 |
Class at
Publication: |
34/72 |
International
Class: |
F26B 021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2000 |
JP |
2000-063678 |
Apr 26, 2000 |
JP |
2000-125805 |
Apr 26, 2000 |
JP |
2000-125806 |
Claims
What is claimed is:
1. A substrate dryer for drying a substrate cleaned with de-ionized
water, comprising: a cleaning bath storing de-ionized water for
dipping a substrate in said de-ionized water thereby cleaning said
substrate; a pull-up robot pulling up cleaned said substrate from
said cleaning bath; and a drying gas supply part supplying drying
gas containing silicone gas to the main surface of said substrate
being pulled up by said pull-up robot.
2. The substrate dryer according to claim 1, wherein said drying
gas supply part is provided on a side portion of said substrate
being pulled up from said cleaning bath by said pull-up robot, and
supplies a stream of said drying gas containing said silicone gas
toward said substrate.
3. The substrate dryer according to claim 2, wherein said drying
gas supply part substantially horizontally forms a stream of said
drying gas on the gas-liquid interface of said de-ionized water
stored in said cleaning bath.
4. The substrate dryer according to claim 3, wherein said cleaning
bath cleans a plurality of substrates stacked at intervals from
each other, said pull-up robot collectively pulls up said plurality
of substrates, and said drying gas supply part forms said stream of
said drying gas between the respective ones of said plurality of
substrates being pulled up by said pull-up robot.
5. The substrate dryer according to claim 4, further comprising: a
drying gas heating part heating said drying gas to a temperature
higher than that of said substrates to be dried by at least
10.degree. C. and feeding the same to said drying gas supply
part.
6. The substrate dryer according to claim 5, wherein said silicone
gas is a gas phase of low-molecular silicone.
7. The substrate dryer according to claim 6, wherein said drying
gas is made of only said silicone gas.
8. The substrate dryer according to claim 6, wherein said drying
gas contains said silicone gas and not more than 10 volume % of gas
of a water-soluble solvent.
9. A substrate dryer for drying a substrate cleaned with de-ionized
water, comprising: a cleaning bath storing de-ionized water for
dipping a substrate in said de-ionized water thereby cleaning said
substrate; a pull-up robot pulling up cleaned said substrate from
said cleaning bath; and a drying gas supply part supplying drying
gas containing gas of a fluorine-based inactive liquid to the main
surface of said substrate being pulled up by said pull-up
robot.
10. The substrate dryer according to claim 9, wherein said drying
gas supply part is provided on a side portion of said substrate
being pulled up from said cleaning bath by said pull-up robot, and
supplies a stream of said drying gas containing said gas of said
fluorine-based inactive liquid toward said substrate.
11. The substrate dryer according to claim 10, wherein said drying
gas supply part substantially horizontally forms said stream of
said drying gas on the gas-liquid interface of said de-ionized
water stored in said cleaning bath.
12. The substrate dryer according to claim 11, wherein said
cleaning bath cleans a plurality of substrates stacked at intervals
from each other, said pull-up robot collectively pulls up said
plurality of substrates, and said drying gas supply part forms said
stream of said drying gas between the respective ones of said
plurality of substrates being pulled up by said pull-up robot.
13. The substrate dryer according to claim 12, further comprising:
a drying gas heating part heating said drying gas to a temperature
higher than that of said substrates to be dried by at least
10.degree. C. and feeding the same to said drying gas supply
part.
14. The substrate dryer according to claim 13, wherein said
fluorine-based inactive liquid is expressed in the following
general formula: (C.sub.(n)F.sub.(2n+1)--O--R.sub.1) where R.sub.1
represents an alkyl group and n represents a natural number.
15. The substrate dryer according to claim 14, wherein said drying
gas is made of only said gas of said fluorine-based inactive
liquid.
16. The substrate dryer according to claim 14, wherein said drying
gas contains said gas of said fluorine-based inactive liquid and
not more than 10 volume % of gas of a water-soluble solvent.
17. The substrate dryer according to claim 14, wherein said
fluorine-based inactive liquid is ethyl perfluorobutyl ether.
18. A substrate dryer for drying a substrate cleaned with
de-ionized water, comprising: a cleaning bath storing de-ionized
water for dipping a substrate in said de-ionized water thereby
cleaning said substrate; a pull-up robot pulling up cleaned said
substrate from said cleaning bath; and a silicone layer forming
part supplying a drying liquid containing silicone to the surface
of said de-ionized water stored in said cleaning bath for forming a
silicone layer, wherein said pull-up robot pulls up cleaned said
substrate from said cleaning bath thereby passing said substrate
through said silicone layer formed on the surface of said
de-ionized water stored in said cleaning bath.
19. The substrate dryer according to claim 18, further comprising:
an ultrasonic vibration supply part supplying ultrasonic vibration
to said de-ionized water stored in said cleaning bath and said
silicone layer formed on the surface of said de-ionized water.
20. The substrate dryer according to claim 19, further comprising:
a de-ionized water supply part supplying said de-ionized water to
said cleaning bath, wherein said de-ionized water supply part
supplies said de-ionized water to said cleaning bath thereby
continuously discharging said de-ionized water and said silicone
from an upper end of said cleaning bath and said silicone layer
forming part continuously supplies said drying liquid to said
cleaning bath while said pull-up robot passes said substrate
through said silicone layer.
21. The substrate dryer according to claim 20, wherein said
silicone is low-molecular silicone.
22. The substrate dryer according to claim 21, wherein said drying
liquid is made of only said silicone.
23. The substrate dryer according to claim 21, wherein said drying
liquid contains said silicone and not more than 10 volume % of a
water-soluble solvent.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a substrate dryer for
drying a semiconductor substrate, a glass substrate for a liquid
crystal display unit, a glass substrate for a photomask, a
substrate for an optical disk or the like (hereinafter simply
referred to as "substrate") cleaned with de-ionized water (pure
water).
[0003] 2. Description of the Background Art
[0004] In general, a surface treatment such as etching with a
chemical solution or cleaning with de-ionized water and a drying
treatment are successively performed on the aforementioned
substrate, to achieve a series of substrate treatments. In such
series of treatments, the drying treatment is generally executed as
the final treatment following finishing cleaning with de-ionized
water.
[0005] In general, the substrate is dried by a method (the
so-called spin drying) of rotating the substrate at a high speed
and draining water by centrifugal force or a method employing IPA
(isopropyl alcohol). Following recent complication of the
semiconductor device structure, however, a drying failure called as
a water mark is noted, and the drying method employing IPA hardly
causing this problem is now forming the mainstream. The water mark,
which is a drying spot caused by moisture adhering to the surface
of the substrate and reacting with silicon forming the substrate
and oxygen contained in the air to form particles, is readily
caused as the time when the moisture adheres to the surface of the
substrate increases.
[0006] The drying method employing IPA includes a method (IPA vapor
drying) of spraying vapor of IPA onto the surface of the substrate
to which moisture adheres or a method (Marangoni drying) of pulling
up and passing the substrate through a thin liquid layer of IPA
formed on the surface of de-ionized water. IPA substitutes for the
moisture adhering to the surface of the substrate and vaporizes in
a short time, to relatively hardly cause a water mark in the drying
method employing IPA.
[0007] As generally known, however, importance is recently attached
to environmental problems, while IPA applies load on the
environment if discharged as such. In any of the aforementioned
methods, therefore, a prescribed disposal treatment must be
performed for making IPA harmless to the environment. However, such
a disposal treatment requires a considerably high cost as a matter
of course, to disadvantageously increase the cost for the substrate
treatment.
[0008] Further, the structure of a device formed on the surface of
the substrate is recently so refined.multidot.complicated that the
problem of a water mark may arise also in the drying method
employing IPA. In Marangoni drying, further, a Marangoni convection
formed on the interface between the liquid layer of IPA and the
de-ionized water may disadvantageously result in transfer of
particles adhering to the surface of the substrate.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a substrate dryer for
drying a substrate cleaned with de-ionized water.
[0010] According to a first aspect of the present invention, a
substrate dryer for drying a substrate cleaned with de-ionized
water comprises a cleaning bath storing de-ionized water for
dipping a substrate in the de-ionized water thereby cleaning the
substrate, a pull-up robot pulling up the cleaned substrate from
the cleaning bath, and a drying gas supply part supplying drying
gas containing silicone gas to the main surface of the substrate
being pulled up by the pull-up robot.
[0011] Silicone can suppress formation of a water mark also on a
substrate having a refined.multidot.complicated structure due to
its excellent permeability.multidot.dryability while applying no
load to the environment. Therefore, no specific treatment is
required for disposing silicone but increase of the cost required
for the drying treatment can be suppressed.
[0012] According to another aspect of the present invention, a
substrate dryer for drying a substrate cleaned with de-ionized
water comprises a cleaning bath storing de-ionized water for
dipping a substrate in the de-ionized water thereby cleaning the
substrate, a pull-up robot pulling up the cleaned substrate from
the cleaning bath, and a drying gas supply part supplying drying
gas containing gas of a fluorine-based inactive liquid to the main
surface of the substrate being pulled up by the pull-up robot.
[0013] The fluorine-based inactive liquid can suppress formation of
a water mark also on a substrate having a
refined.multidot.complicated structure due to its excellent
permeability.multidot.dryability while applying no load to the
environment. Therefore, no specific treatment is required for
disposing the fluorine-based inactive liquid but increase of the
cost required for the drying treatment can be suppressed.
[0014] According to still another aspect of the present invention,
a substrate dryer for drying a substrate cleaned with de-ionized
water comprises a cleaning bath storing de-ionized water for
dipping a substrate in the de-ionized water thereby cleaning the
substrate, a pull-up robot pulling up the cleaned substrate from
the cleaning bath, and a silicone layer forming part supplying a
drying liquid containing silicone to the surface of the de-ionized
water stored in the cleaning bath for forming a silicone layer,
while the pull-up robot pulls up the cleaned substrate from the
cleaning bath thereby passing the substrate through the silicone
layer formed on the surface of the de-ionized water stored in the
cleaning bath.
[0015] Silicone allows no adhesion of particles onto a substrate
having a refined.multidot.complicated structure due to its
excellent permeability.multidot.dryability while applying no load
to the environment. Therefore, no specific treatment is required
for disposing silicone but increase of the cost required for the
drying treatment can be suppressed.
[0016] Accordingly, an object of the present invention is to
provide a substrate dryer causing no water mark also on a substrate
having a refined.multidot.complicated structure and capable of
suppressing increase of a cost required for a drying treatment.
[0017] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 illustrates the overall structure of a substrate
dryer according to a first embodiment of the present invention;
[0019] FIG. 2 is a plan view of a drying vessel in the substrate
dryer shown in FIG. 1;
[0020] FIG. 3 is a side elevational view of the drying vessel of
the substrate dryer shown in FIG. 1;
[0021] FIGS. 4 to 7 illustrate the process of a drying treatment in
the substrate dryer shown in FIG. 1;
[0022] FIG. 8 illustrates the overall structure of a substrate
dryer according to a third embodiment of the present invention;
[0023] FIG. 9 is a plan view of a drying vessel in the substrate
dryer shown in FIG. 8;
[0024] FIG. 10 is a side elevational view of the drying vessel in
the substrate dryer shown in FIG. 8;
[0025] FIGS. 11 to 15 illustrate the process of a drying treatment
in the substrate dryer shown in FIG. 8; and
[0026] FIG. 16 illustrates a substrate being pulled up and passed
through a silicone layer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] <First Embodiment>
[0028] FIG. 1 illustrates the overall structure of a substrate
dryer according to a first embodiment of the present invention.
This substrate dryer is generally formed by a drying vessel 10 for
performing a drying treatment and a mechanism supplying various
types of gas to the drying vessel 10. FIGS. 2 and 3 are a plan view
and a side elevational view of the drying vessel 10
respectively.
[0029] The drying vessel 10 is a box which can be brought into a
closed space state by closing a lid (not shown). Substrates W are
introduced into/discharged from the drying vessel 10 by a
transporting robot (not shown) in a state opening the lid.
[0030] A cleaning bath 20 is fixed/arranged in the drying vessel
10. The cleaning bath 20 stores de-ionized water for dipping the
substrates W in the de-ionized water thereby cleaning the
substrates W. The cleaning bath 20 is provided with a de-ionized
water supply mechanism (not shown) and a drain mechanism (not
shown), which can supply new de-ionized water to the cleaning bath
20 and drain used de-ionized water from the cleaning bath 20
respectively. The cleaning bath 20 may be further provided with a
mechanism for supplying.multidot.discharging a chemical solution
such as an etching solution, in addition to those for the
de-ionized water.
[0031] A lifter LH is provided in the drying vessel 10 (see FIGS. 2
and 3). The lifter LH has a function of vertically moving up/down a
lifter arm 25. Three holding bars 26a, 26b and 26c are fixed to the
lifter arm 25 so that the longitudinal direction thereof is
substantially horizontal, while a plurality of holding grooves for
receiving outer edge portions of the substrates W and holding the
substrates W in an upright state are arranged on each of the three
holding bars 26a, 26b and 26c at regular intervals.
[0032] Due to the aforementioned structure, the lifter LH can move
the plurality of substrates W stacked/arranged in parallel with
each other and held by the three holding bars 26a, 26b and 26c at
intervals between positions dipped in the de-ionized water stored
in the cleaning bath 20 and positions pulled up from the de-ionized
water. A mechanism such as a feed screw mechanism employing ball
screws or a belt mechanism employing pulleys and a belt can be
employed for the lifter LH as the mechanism for moving up/down the
lifter arm 25.
[0033] Further, two drying gas supply nozzles 30 and two nitrogen
gas supply nozzles 50 are provided in the drying vessel 10. The two
drying gas supply nozzles 30 and the two nitrogen gas supply
nozzles 50 are hollow cylindrical members so arranged that the
longitudinal direction thereof is substantially horizontal (in
parallel with the three holding bars 26a, 26b and 26c). Each drying
gas supply nozzle 30 is formed with a plurality of discharge holes
30a, and each nitrogen gas supply nozzle 50 is also formed with a
plurality of discharge holes 50a (see FIG. 3).
[0034] The discharge holes 30a provided on the drying gas supply
nozzles 30 are so formed that the discharge direction thereof is
substantially horizontal. On the other hand, the discharge holes
50a provided on the nitrogen gas supply nozzles 50 are so formed
that the discharge direction is obliquely downward. The discharge
holes 30a are formed to be positioned between the plurality of
substrates W arranged/held in parallel with each other by the three
holding bars 26a, 26b and 26c of the lifter LH (see FIG. 3).
[0035] The drying gas supply nozzles 30 are supplied with drying
gas from a drying gas supply mechanism provided outside the drying
vessel 10. This drying gas supply mechanism is formed by a nitrogen
gas supply source 32, a drying gas generation part 31, a pipe 35
and a heater 37. The drying gas generation part 31 stores liquid
silicone.
[0036] Silicone, the general term for chain organopolysiloxane
having a main chain of (Si--O).sub.x, includes liquid type, grease
type, rubber type and resin type ones depending on the degrees of
polymerization. The substrate dryer according to the first
embodiment employs liquid type low-molecular silicone having a low
degree of polymerization (low viscosity). This low-molecular
silicone has the following structural formula: 1
[0037] The low-molecular silicone in the present invention is in
the range of a dimer to a pentamer (n: 2 to 5), and the substrate
dryer according to the first embodiment employs a dimer. The degree
of polymerization of the low-molecular silicone in the present
invention is limited to the range of a dimer to a pentamer since
silicone in this range is in a liquid state having low viscosity
and hence can be readily supplied as drying gas by nitrogen
bubbling described later. Throughout the specification, the term
"low-molecular silicone" stands for that in the range of a dimer to
a pentamer unless otherwise stated.
[0038] The nitrogen gas supply source 32 can supply nitrogen gas
into the liquid silicone stored in the drying gas generation part
31 as bubbles, for performing the so-called bubbling with nitrogen
gas. A gas phase of the silicone is mixed into the nitrogen gas due
to this bubbling, so that drying gas consisting of silicone gas can
be fed to the pipe 35 with carrier gas of the nitrogen gas.
According to the first embodiment, the drying gas generation part
31 stores only the liquid silicone, and the drying gas consists of
only the silicone gas. The concentration of the drying gas
contained in the gas flowing through the pipe 35 may be set to
about 2 volume %, and the flow velocity thereof may be set to about
101/min.
[0039] The heater 37 is provided on an intermediate portion of the
path of the pipe 35, for heating the drying gas carried by the
carrier gas. At this time, the heater 37 heats the drying gas to a
temperature higher than that of the substrates W to be dried in the
drying vessel 10 by at least 10.degree. C. When the temperature of
the substrates W to be dried is 23.degree. C., for example, the
heater 37 heats the drying gas to at least 33.degree. C. The drying
gas heated by the heater 37 is further fed to the drying gas supply
nozzles 30 through the pipe 35, and supplied into the drying vessel
10 from the discharge holes 30a of the drying gas supply nozzles
30.
[0040] While the mode of supplying the drying gas from the drying
gas supply nozzles 30 is further described later, the drying gas
supply nozzles 30 are provided on side portions of the substrates W
being pulled up from the cleaning bath 20 by the lifter LH, and
hence it follows that the drying gas is supplied from the side
portions of the substrates W being pulled up. The drying gas supply
nozzles 30 substantially horizontally form streams of the drying
gas on the gas-liquid interface of the de-ionized water stored in
the cleaning bath 20 between the plurality of substrates W being
pulled up.
[0041] On the other hand, the nitrogen gas supply source 52
provided outside the drying vessel 10 supplies nitrogen gas to the
nitrogen gas supply nozzles 50. The nitrogen gas supply source 52
is connected with the nitrogen gas supply nozzles 50 through a pipe
55. A heater 57 is provided on an intermediate portion of the path
of the pipe 55. The nitrogen gas fed from the nitrogen gas supply
source 52 passes through the pipe 55, is heated by the heater 57 on
the intermediate portion and thereafter reaches the nitrogen gas
supply nozzles 50, to be obliquely downwardly discharged from the
discharge holes 50a of the nitrogen gas supply nozzles 50.
[0042] The procedure of the drying treatment in the substrate dryer
according to the first embodiment having the aforementioned
structure is now described with reference to FIGS. 4 to 7. FIGS. 4
to 7 illustrate the process of the drying treatment in the
aforementioned substrate dryer.
[0043] Referring to FIG. 4, the substrates W are subjected to a
cleaning treatment (rinsing) with de-ionized water. In this
rinsing, the lifter LH holds the plurality of substrates W
stacked/arranged at intervals and dips the same in the de-ionized
water stored in the cleaning bath 20. At this time, the de-ionized
water is continuously supplied from a lower portion of the cleaning
bath 20, to regularly overflow the cleaning bath 20 from its upper
end (the so-called up-flow treatment). Thus, contaminants are
separated from the substrates W and discharged from the cleaning
bath 20. The used de-ionized water overflowing the cleaning bath 20
is collected and discharged from the drying vessel 10, as a matter
of course. In advance of the rinsing, the substrates W may be
subjected to a surface treatment with a chemical solution in the
cleaning bath 20, or may be treated with a chemical solution in
another vessel and introduced into the drying vessel 10.
[0044] In the stage of the rinsing, the drying gas supply nozzles
30 stop supplying the drying gas. On the other hand, the nitrogen
gas supply nozzles 50 may supply the nitrogen gas to the drying
vessel 10.
[0045] When the rinsing is terminated after a lapse of a prescribed
time, the drying gas supply nozzles 30 start supplying the drying
gas while the lifter LH collectively pulls up the held plurality of
substrates W (FIG. 5). At this time, the drying gas supply nozzles
30 supply the drying gas from the side portions of the substrates W
being pulled up from the cleaning bath 20 by the lifter LH, and
substantially horizontally form streams of the drying gas on the
gas-liquid interface of the de-ionized water stored in the cleaning
bath 20 between the substrates W, as shown by arrows A5 in FIG.
5.
[0046] Large quantities of droplets of the de-ionized water adhere
to the main surfaces of the substrates W being pulled up by the
lifter LH, and the drying gas supply nozzles 30 supply the streams
of the drying gas consisting of silicone gas to the main surfaces
of the substrates W to which the de-ionized water adheres. The
heater 37 heats the drying gas supplied from the drying gas supply
nozzles 30 to a temperature higher than that of the pulled-up
substrates W by at least 10C. Therefore, the silicone gas is
readily condensed on the main surfaces of the respective ones of
the plurality of substrates W, so that the liquid silicone
substitutes for the droplets and adheres to the surfaces of the
substrates W.
[0047] Also in the stage of pulling up the substrates W by the
lifter LH, the de-ionized water is continuously supplied to the
cleaning bath 20 from the lower portion thereof while overflowing
the cleaning bath 20 from its upper end, for discharging impurities
from the cleaning bath 20.
[0048] Then, the lifter LH completely separates the substrates W
from the de-ionized water stored in the cleaning bath 20, and the
drying gas supply nozzles 30 stop supplying the drying gas while
the nitrogen gas supply nozzles 50 supply the nitrogen gas or the
nitrogen gas heated by the heater 57 (FIG. 6). Thus, the inactive
nitrogen gas substitutes for the atmosphere in the drying vessel
10, and silicone adhering to the substrates W vaporizes.
Particularly when the heated nitrogen gas is sprayed to the
substrates W, vaporization of silicone is prompted for reducing the
drying time. In this stage, supply of the de-ionized water to the
cleaning bath 20 is stopped while the used de-ionized water is
discharged from the cleaning bath 20.
[0049] Thereafter the nitrogen gas supply nozzles 50 stop supplying
the nitrogen gas after the silicone adhering to the substrates W
completely vaporizes, and the lid of the drying vessel 10 is opened
for discharging the dried substrates W from the drying vessel 10
(FIG. 7). Thus, the series of treatments of the substrates W is
terminated.
[0050] As hereinabove described, the substrate dryer according to
the first embodiment supplies the streams of the low-molecular
silicone gas to the main surfaces of the substrates W to which
de-ionized water adheres, and condenses the silicone gas on the
main surfaces for replacing the droplets of the de-ionized water
with the silicone thereby drying the substrates W. Silicone, also
employed for cosmetics or the like, is a material applying only
light load to the environment and causing no problem such as
disruption of the ozone layer or global warning, which requires no
specific treatment in disposal. Thus, increase of the cost required
for the drying treatment can be suppressed.
[0051] Further, the low-molecular silicone has small surface
tension of not more than 16.5 dyn/cm while those of water and IPA
are 71.8 dyn/cm and 20.8 dyn/cm respectively. This means that the
low-molecular silicone having small surface tension has higher
permeability than IPA. Thus, the low-molecular silicone can readily
substitute for moisture also in the recent
refined.multidot.complicated device structure, particularly in a
portion such as a hole having a large aspect ratio (the ratio of
the length to the diameter).
[0052] Therefore, the drying method employing the low-molecular
silicone exhibits excellent dryability also in the recent
refined.multidot.complic- ated device structure, and hardly causes
the problem of a water mark resulting from adhering moisture.
[0053] Further, the low-molecular silicon also has small latent
heat of vaporization of not more than 300 J/g while those of water
and IPA are 2256 J/g and 674 J/g respectively.
[0054] This means that the low-molecular silicone having small
latent heat of vaporization has a higher drying speed than IPA.
Therefore, the drying method employing the low-molecular silicone
can reduce the time required for drying as compared with the case
of employing IPA, improve the throughput, and further suppress
formation of a water mark resulting from adhering moisture.
[0055] According to the first embodiment, the drying gas supply
nozzles 30 supply the drying gas of the low-molecular silicone from
the side portions of the substrates W being pulled up from the
cleaning bath 20 by the lifter LH and substantially horizontally
form the streams of the drying gas on the gas-liquid interface of
the de-ionized water stored in the cleaning bath 20, thereby
spraying the drying gas to separated areas substantially
simultaneously with separation of the surfaces of the substrates W
from the de-ionized water. Thus, the moisture on the main surfaces
of the substrates W are hardly exposed to the outside air but
quickly replaced with the low-molecular silicone, and formation of
a water mark can be more efficiently suppressed.
[0056] Part of the supplied drying gas drops into the cleaning bath
20 to be mixed with the de-ionized water at this time, while the
silicone is water-insoluble, completely separated from water and
causes no Marangoni convection, to cause no problem such as
transfer of particles resulting from a Marangoni convection.
[0057] The drying gas supply nozzles 30 forming the streams of the
drying gas between the plurality of substrates W being pulled up by
the lifter LH can homogeneously spray the drying gas of the
low-molecular silicone to the respective substrates W.
[0058] Further, the heater 37 heats the drying gas to a temperature
higher than that of the pulled-up substrates W by at least
10.degree. C., whereby the low-molecular silicone is readily
condensed on the main surfaces of the substrates W so that the
liquid silicone can quickly substitute for the droplets adhering to
the substrates W and formation of a water mark can be more
effectively suppressed as a result.
[0059] While the first embodiment of the present invention has been
described, the present invention is not restricted to the
aforementioned example. While the substrate dryer according to the
aforementioned first embodiment stores only the liquid
low-molecular silicone in the drying gas generation part 31 for
forming the drying gas only by the silicone gas, the drying gas
generation part 31 may alternatively store a mixed solution of
liquid low-molecular silicone and a water-soluble solvent for
preparing the drying gas from a gas mixture of the silicone gas and
gas of the water-soluble solvent. The water-soluble solvent can be
prepared from alcohol such as IPA, acetone, ketone or carboxylic
acid, for example. The content of the gas of the water-soluble
solvent in the mixed drying gas must be not more than 10 volume %.
If the content of the gas of the water-soluble solvent in the mixed
drying gas exceeds 10 volume %, the ratio of the silicone gas in
the mixed drying gas is so reduced that the aforementioned effect
resulting from employment of silicone is hard to attain and a
specific problem (a problem of disposal or the like) results from
employment of IPA or the like. Such a problem hardly arises when
the content of the gas of the water-soluble solvent in the mixed
drying gas is not more than 10 volume %.
[0060] While the substrate dryer according to the first embodiment
generates the drying gas by bubbling the nitrogen gas, the drying
gas generation method is not restricted to this but the drying gas
generation part 31 may be provided with a heater for heating liquid
silicone (or a mixed solution of liquid silicone and a
water-soluble solvent) thereby generating drying gas, for
example.
[0061] While the substrate dryer according to the first embodiment
heats the drying gas by the heater 37 to a temperature higher than
that of the substrates W to be dried by at least 10.degree. C., the
drying gas may not necessarily be heated. When the drying gas is
not heated, the temperatures of the substrates W and the drying gas
are substantially equivalent to each other to more hardly cause
condensation than the first embodiment, and hence the speed for
pulling up the substrates W by the lifter LH must be reduced (to
about 1 mm/sec.) as compared with the first embodiment. When
reducing the speed for pulling up the substrates W, condensation of
silicone is caused without heating the drying gas, and an effect
similar to that of the first embodiment can be attained.
[0062] While the drying gas supply nozzles 30 are provided on the
side portions of the substrates W being pulled up from the cleaning
bath 20 by the lifter LH in the first embodiment, the present
invention is not restricted to this but the drying gas supply
nozzles 30 may be located on positions capable of supplying streams
of the drying gas to the main surfaces of the substrates W.
[0063] While the substrate dryer according to the first embodiment
is the so-called batch-system apparatus collectively treating the
plurality of substrates W, the technique of the aforementioned
embodiment is also applicable to the so-called sheet-feed apparatus
treating the substrates W one by one.
[0064] <Second Embodiment>
[0065] A substrate dryer according to a second embodiment of the
present invention is now described. The basic structure of the
substrate dryer according to the second embodiment is absolutely
identical to that of the first embodiment (see FIGS. 1 to 3).
[0066] The substrate dryer according to the second embodiment is
different from the first embodiment in a point that the same
employs gas of a fluorine-based inactive liquid as drying gas in
place of the low-molecular silicone. In other words, a drying gas
generation part 31 stores the fluorine-based inactive liquid in
place of the liquid silicone.
[0067] The fluorine-based inactive liquid is an inactive material
not corroding a material such as a metal, plastic or rubber,
nonflammable and applies no load to the environment. The
fluorine-based inactive liquid employed in the present invention
has the following general structural formula:
[C.sub.(n)F.sub.(2n+1)--O--R.sub.1] (2)
[0068] where R.sub.1 represents an alkyl group, and n represents a
natural number. The substrate dryer according to the present
invention employs ethyl perfluorobutyl ether as the fluorine-based
inactive liquid. This ethyl perfluorobutyl ether has the following
structural formula:
[C.sub.4F.sub.9--O--C.sub.2H.sub.5] (3)
[0069] A nitrogen gas supply source 32 can supply nitrogen gas to
the fluorine-based inactive liquid stored in the drying gas
generation part 31 as bubbles, for performing the so-called
bubbling with the nitrogen gas. Due to this bubbling, a gas phase
of the fluorine-based inactive liquid is mixed into the nitrogen
gas, so that drying gas consisting of gas of the fluorine-based
inactive liquid can be fed to a pipe 35 with carrier gas of the
nitrogen gas. According to the second embodiment, the drying gas
generation part 31 stores only the fluorine-based inactive liquid,
and the drying gas is prepared from only the gas of the
fluorine-based inactive liquid. The concentration of the drying gas
in the gas flowing through the pipe 35 may be set to about 2 volume
%, and the flow velocity thereof may be set to about 101/min.
[0070] The remaining structure of the substrate dryer according to
the second embodiment is identical to that of the substrate dryer
according to the first embodiment, and hence redundant description
is omitted. The procedure of a drying treatment in the substrate
dryer according to the second embodiment is also identical to that
of the first embodiment (see FIGS. 4 to 7). In other words, after
the stage of the rinsing, large quantities of droplets of
de-ionized water adhere to the main surfaces of substrates W being
pulled up by a lifter LH, and drying gas supply nozzles 30 supply
streams of the drying gas consisting of the gas of the
fluorine-based inactive liquid to the main surfaces of the
substrates W. A heater 37 heats the drying gas supplied from the
drying gas supply nozzles 30 to a temperature higher than that of
the pulled-up substrates W by at least 10.degree. C. Therefore, the
gas of the fluorine-based inactive liquid is readily condensed on
the main surfaces of the respective ones of the plurality of
substrates W, so that the fluorine-based inactive liquid
substitutes for the droplets and adheres to the surfaces of the
substrates W.
[0071] Then, the lifter LH completely separates the substrates W
from the de-ionized water stored in a cleaning bath 20, and the
drying gas supply nozzles 30 stop supplying the drying gas while
nitrogen gas supply nozzles 50 supply nitrogen gas or the nitrogen
gas heated by a heater 57. Thus, the inactive nitrogen gas
substitutes for the atmosphere in a drying vessel 10, and the
fluorine-based inactive liquid adhering to the substrates W
vaporizes. Particularly when the heated nitrogen gas is sprayed to
the substrates W, vaporization of the fluorine-based inactive gas
is prompted for reducing the drying time. In this stage, supply of
the de-ionized water to the cleaning bath 20 is stopped while the
used de-ionized water is discharged from the cleaning bath 20.
[0072] Thereafter the nitrogen gas supply nozzles 50 stop supplying
the nitrogen gas after the fluorine-based inactive liquid adhering
to the substrates W completely vaporizes, and a lid of the drying
vessel 10 is opened for discharging the dried substrates W from the
drying vessel 10. Thus, the serial drying treatment of the
substrates W is terminated.
[0073] As hereinabove described, the substrate dryer according to
the second embodiment supplies the streams of the gas of the
fluorine-based inactive liquid to the main surfaces of the
substrates W to which de-ionized water adheres, and condenses the
gas of the fluorine-based inactive liquid on the main surfaces for
replacing the droplets of de-ionized water with the fluorine-based
inactive liquid thereby drying the substrates W. The fluorine-based
inactive liquid, also employed as substitutional flon, is a
material applying only light load to the environment and causing no
problem such as disruption of the ozone layer or global warming,
which requires no specific treatment in disposal. Thus, increase of
the cost required for the drying treatment can be suppressed.
[0074] Further, the fluorine-based inactive liquid and the gas
thereof are nonflammable, and hence the dryer may not be provided
with a specific safety mechanism such as an explosion-proof
structure. Increase of the cost required for the drying treatment
can be suppressed also by this.
[0075] In addition, the fluorine-based inactive liquid has small
surface tension of not more than 18 dyn/cm while those of water and
IPA are 71.8 dyn/cm and 20.8 dyn/cm respectively. This means that
the fluorine-based inactive liquid having small surface tension has
higher permeability than IPA. Thus, the fluorine-based inactive
liquid can readily substitute for moisture also in the recent
refined.multidot.complicated device structure particularly in a
portion such as a hole having a large aspect ratio (the ratio of
the length to the diameter). Therefore, the drying method employing
the fluorine-based inactive liquid exhibits excellent dryability
also in the recent refined.multidot.complicated device structure,
and hardly causes the problem of a water mark resulting from
adhering moisture.
[0076] Further, the fluorine-based inactive liquid also has small
latent heat of vaporization of not more than 84 J/g while those of
water and IPA are 2256 J/g and 674 J/g respectively. This means
that the fluorine-based inactive liquid having small latent heat of
vaporization has a higher drying speed than IPA. Therefore, the
drying method employing the fluorine-based inactive liquid can
reduce the time required for drying as compared with the case of
employing IPA, improve the throughput, and further suppress
formation of a water mark resulting from adhering moisture.
[0077] According to the second embodiment, the drying gas supply
nozzles 30 supply the drying gas of the fluorine-based inactive
liquid from the side portions of the substrates W being pulled up
from the cleaning bath 20 by the lifter LH and substantially
horizontally form the streams of the drying gas on the gas-liquid
interface of the de-ionized water stored in the cleaning bath 20,
thereby spraying the drying gas to separated areas substantially
simultaneously with separation of the surfaces of the substrates W
from the de-ionized water. Thus, it follows that the moisture on
the main surfaces of the substrates W are hardly exposed to the
outside air but quickly replaced with the fluorine-based inactive
liquid, and formation of a water mark can be more efficiently
suppressed.
[0078] Part of the supplied drying gas drops into the cleaning bath
20 to be mixed with the de-ionized water at this time, while the
fluorine-based inactive liquid is water-insoluble, completely
separated from water and causes no Marangoni convection, to cause
no problem such as transfer of particles resulting from a Marangoni
convection.
[0079] The drying gas supply nozzles 30 forming the streams of the
drying gas between the plurality of substrates W being pulled up by
the lifter LH can homogeneously spray the drying gas of the
fluorine-based inactive liquid to the respective substrates W.
[0080] Further, the heater 37 heats the drying gas to a temperature
higher than that of the pulled-up substrates W by at least
10.degree. C., whereby the fluorine-based inactive liquid is
readily condensed on the main surfaces of the substrates W so that
the droplets adhering to the substrates W can be quickly replaced
with the fluorine-based inactive liquid and formation of a water
mark can be more effectively suppressed as a result.
[0081] While the second embodiment of the present invention has
been described, the present invention is not restricted to the
aforementioned example. While the substrate dryer according to the
aforementioned second embodiment stores only the fluorine-based
inactive liquid in the drying gas generation part 31 for forming
the drying gas only by the gas of the fluorine-based inactive
liquid, the drying gas generation part 31 may alternatively store a
mixed solution of the fluorine-based inactive liquid and a
water-soluble solvent for preparing the drying gas from a gas
mixture of the gas of the fluorine-based inactive liquid and gas of
the water-soluble solvent. The water-soluble solvent can be
prepared from alcohol such as IPA, acetone, ketone or carboxylic
acid, for example. The content of the gas of the water-soluble
solvent in the mixed drying gas must be not more than 10 volume %.
If the content of the gas of the water-soluble solvent in the mixed
drying gas exceeds 10 volume %, the ratio of the gas of the
fluorine-based inactive liquid in the mixed drying gas is so
reduced that the aforementioned effect resulting from employment of
the fluorine-based inactive liquid is hard to attain and a specific
problem (a problem of disposal or the like) results from employment
of IPA or the like. Such a problem hardly arises when the content
of the gas of the water-soluble solvent in the mixed drying gas is
not more than 10 volume %.
[0082] While the substrate dryer according to the second embodiment
generates the drying gas by bubbling the nitrogen gas, the drying
gas generation method is not restricted to this but the drying gas
generation part 31 may be provided with a heater for heating the
fluorine-based inactive liquid (or a mixed solution of the
fluorine-based inactive liquid and a water-soluble solvent) thereby
generating drying gas, for example.
[0083] While the substrate dryer according to the second embodiment
heats the drying gas by the heater 37 to a temperature higher than
that of the substrates W to be dried by at least 10.degree. C., the
drying gas may not necessarily be heated. When the drying gas is
not heated, the temperatures of the substrates W and the drying gas
are substantially equivalent to each other to more hardly cause
condensation than the second embodiment, and hence the speed for
pulling up the substrates W by the lifter LH must be reduced (to
about 1 mm/sec.) as compared with the aforementioned embodiment.
When reducing the speed for pulling up the substrates W,
condensation of the fluorine-based inactive liquid is caused
without heating the drying gas, and an effect similar to that of
the aforementioned embodiment can be attained.
[0084] While the drying gas supply nozzles 30 are provided on the
side portions of the substrates W being pulled up from the cleaning
bath 20 by the lifter LH in the second embodiment, the present
invention is not restricted to this but the drying gas supply
nozzles 30 may be located on positions capable of supplying the
streams of the drying gas to the main surfaces of the substrates
W.
[0085] While the fluorine-based inactive liquid is prepared from
ethyl perfluorobutyl ether in the second embodiment, the
fluorine-based inactive liquid is not restricted to this but may be
prepared from methyl perfluoroisobutyl ether, ethyl perfluorobutyl
ether, ethyl perfluoroisobutyl ether, propyl perfluorobutyl ether,
propyl perfluoroisobutyl ether, methyl perfluoropropyl ether,
methyl perfluoroisopropyl ether, ethyl perfluoropropyl ether, ethyl
perfluoroisopropyl ether, methyl perfluoropentyl ether or ethyl
perfluoropentyl ether, for example, if they include the structure
as shown in the chemical formula (2).
[0086] While the substrate dryer according to the second embodiment
is the so-called batch-system apparatus collectively treating the
plurality of substrates W, the technique of the second embodiment
is also applicable to the so-called sheet-feed apparatus treating
the substrates W one by one.
[0087] <Third Embodiment>
[0088] A substrate dryer according to a third embodiment of the
present invention is now described. FIG. 8 illustrates the overall
structure of the substrate dryer according to the third embodiment
of the present invention. This substrate dryer is generally formed
by a drying vessel 10 for drying and a mechanism supplying various
types of gas and liquid to the drying vessel 10. FIGS. 9 and 10 are
a plan view and a side elevational view of the drying vessel 10
respectively.
[0089] The drying vessel 10 is a box which can be brought into a
closed space state by closing a lid (not shown). Substrates W are
introduced into/discharged from the drying vessel 10 by a
transporting robot (not shown) in a state opening the lid.
[0090] A cleaning bath 20 is fixed/arranged in the drying vessel
10. The cleaning bath 20 stores de-ionized water for dipping the
substrates W in the de-ionized water thereby cleaning the
substrates W. Two de-ionized water supply nozzles 22 are arranged
on the inner bottom portion of the cleaning bath 20. The de-ionized
water supply nozzles 22 are so provided that the longitudinal
direction thereof is substantially horizontal, and connected with a
de-ionized water supply source 21 provided outside the drying
vessel 10 through a pipe 23. Each de-ionized water supply nozzle 22
is provided with a plurality of discharge holes 22a (see FIG. 10).
Fresh de-ionized water fed from the de-ionized water supply source
21 flows through the pipe 23 and reaches the de-ionized water
supply nozzles 22, to be discharged into the cleaning bath 20 from
the discharge holes 22a of the de-ionized water supply nozzles 22.
The discharge holes 22a are directed obliquely upward, for
discharging the de-ionized water supplied from the de-ionized water
supply nozzles 22 obliquely upward (toward a portion around the
center of the cleaning bath 20).
[0091] The de-ionized water supplied from the de-ionized water
supply nozzles 22 is stored in the cleaning bath 20, to finally
overflow the cleaning bath 20 from its upper end. The de-ionized
water overflowing the cleaning bath 20 from the upper end flows
into a collecting part 24 (see FIG. 8: description of the
collecting part 24 is omitted in FIGS. 9 and 10 for convenience of
illustration). The collecting part 24 is connected to a discharge
mechanism (not shown), so that the de-ionized water flowing into
the collecting part 24 is discharged from the apparatus through the
discharge mechanism.
[0092] An outer bath 60 is provided in the drying vessel 10 outside
the cleaning bath 20. The outer bath 60 is a container of stainless
steel, for example, and an ultrasonic vibration source 61 having an
ultrasonic vibrator is provided on its outer bottom portion. The
clearance between the outer bath 60 and the cleaning bath 20 is
filled with propagation water 62. Thus, ultrasonic vibration of the
megahertz band generated from the ultrasonic vibration source 61 is
transmitted to the cleaning bath 20 through the propagation water
62, and supplied to the de-ionized water and the substrates W
dipped therein through the cleaning bath 20. The ultrasonic
vibration source 61 is not directly provided on the cleaning bath
20 since the ultrasonic vibration source 61 cannot be brought into
direct contact with the cleaning bath 20 of quartz. The ultrasonic
vibration from the ultrasonic vibration source 61 is not restricted
to the megahertz band, as a matter of course.
[0093] A lifter LH is provided in the drying vessel 10 (see FIGS. 9
and 10). The lifter LH has a function of vertically moving up/down
a lifter arm 25. Three holding bars 26a, 26b and 26c are fixed to
the lifter arm 25 so that the longitudinal direction thereof is
substantially horizontal (parallel to the de-ionized water supply
nozzles 22), while a plurality of holding grooves for receiving
outer edge portions of the substrates W and holding the substrate W
in an upright state are arranged on each of the three holding bars
26a, 26b and 26c at regular intervals.
[0094] Due to the aforementioned structure, the lifter LH can move
the plurality of substrates W stacked/arranged in parallel with
each other and held by the three holding bars 26a, 26b and 26c
between positions dipped in the de-ionized water stored in the
cleaning bath 20 and positions pulled up from the de-ionized water.
A mechanism such as a feed screw mechanism employing ball screws or
a belt mechanism employing pulleys and a belt can be employed for
the lifter LH as the mechanism for moving up/down the lifter arm
25.
[0095] Further, two drying liquid supply nozzles 40 and two
nitrogen gas supply nozzles 50 are provided in the drying vessel
10. The two drying liquid supply nozzles 40 and the two nitrogen
gas supply nozzles 50 are hollow cylindrical members so arranged
that the longitudinal direction thereof is substantially horizontal
(in parallel with the three holding bars 26a, 26b and 26c). Each
drying liquid supply nozzle 40 is formed with a plurality of
discharge holes 40a, and each nitrogen gas supply nozzle 50 is also
formed with a plurality of discharge holes 50a (see FIG. 10).
[0096] The discharge holes 40a provided on the drying liquid supply
nozzles 40 are so formed that the discharge direction thereof is
substantially horizontal. On the other hand, the discharge holes
50a provided on the nitrogen gas supply nozzles 50 are so formed
that the discharge direction thereof is obliquely downward. The
discharge holes 40a are located between the plurality of substrates
W arranged/held by the three holding bars 26a, 26b and 26c in
parallel with each other respectively (see FIG. 10).
[0097] The drying liquid supply nozzles 40 are supplied with a
drying liquid from a drying liquid supply mechanism provided
outside the drying vessel 10. This drying liquid supply mechanism
is formed by a drying liquid vessel 41, a feed pump 42 and a pipe
45. The drying liquid vessel 41 stores liquid silicone.
[0098] As described with reference to the first embodiment,
silicone, the general term for chain organopolysiloxane having a
main chain of (Si--O).sub.x, includes liquid type, grease type,
rubber type and resin type ones depending on the degrees of
polymerization. The substrate dryer according to the third
embodiment employs liquid type low-molecular silicone having a low
degree of polymerization (low viscosity). The structural formula of
the low-molecular silicone is identical to the chemical formula (1)
described above with reference to the first embodiment.
[0099] The low-molecular silicone in the present invention is in
the range of a dimer to a pentamer (n: 2 to 5), and the substrate
dryer according to the third embodiment employs a dimer. The degree
of polymerization of the low-molecular silicone in the present
invention is limited to the range of a dimer to a pentamer since
the silicone in this range is in a liquid state having low
viscosity and hence can be readily supplied as the drying liquid by
the feed pump 42 in the third embodiment.
[0100] The feed pump 42 feeds the liquid silicone stored in the
drying liquid vessel 41 to the drying liquid supply nozzles 40
through the pipe 45 as the drying liquid. The drying liquid fed to
the drying liquid supply nozzles 40 are discharged into the
cleaning bath 20 from the discharge holes 40a of the drying liquid
supply nozzles 40 in the form of mist. According to this
embodiment, the drying liquid vessel 41 stores only the liquid
silicone, and the drying liquid is made of only silicone.
[0101] While the behavior of the drying liquid supplied to the
cleaning bath 20 is further described later, water-insoluble
silicone having smaller specific gravity than water forms a thin
liquid layer of silicone on the surface of the de-ionized water
stored in the cleaning bath 20.
[0102] On the other hand, the nitrogen gas supply source 52
provided outside the drying vessel 10 feeds nitrogen gas to the
nitrogen gas supply nozzles 50. The nitrogen gas supply source 52
is connected with the nitrogen gas supply nozzles 50 through a pipe
55. A heater 57 is provided on an intermediate portion of the path
of the pipe 55. The nitrogen gas fed from the nitrogen gas supply
source 52 passes through the pipe 55, is heated by the heater 57 on
the intermediate portion and thereafter reaches the nitrogen gas
supply nozzles 50, to be obliquely downwardly discharged from the
discharge holes 50a of the nitrogen gas supply nozzles 50.
[0103] The procedure of a drying treatment in the substrate dryer
according to the third embodiment having the aforementioned
structure is now described with reference to FIGS. 11 to 15. FIGS.
11 to 15 illustrate the process of the drying treatment in the
substrate dryer according to the third embodiment.
[0104] Referring to FIG. 11, the substrates W are subjected to a
cleaning treatment (rinsing) with de-ionized water. In this
rinsing, the lifter LH holds the plurality of substrates W
stacked/arranged at intervals, and dips the same in the de-ionized
water stored in the cleaning bath 20. At this time, the de-ionized
water is continuously supplied from the de-ionized water supply
nozzles 22 into the cleaning bath 20 to regularly overflow the
cleaning bath 20 from its upper end (the so-called up-flow
treatment). Thus, contaminants such as particles are separated from
the substrates W and discharged from the cleaning bath 20, so that
the substrates W are cleaned. The used de-ionized water overflowing
the cleaning bath 20 flows into a collecting part 24 and is
collected, to be discharged from the drying vessel 10. In advance
of the rinsing, the substrates W may be subjected to a surface
treatment with a chemical solution in the cleaning bath 20, or the
substrates W may be treated with a chemical solution in another
vessel and introduced into the drying vessel 10.
[0105] In the stage of the rinsing, the drying liquid supply
nozzles 40 supply no drying liquid. On the other hand, the nitrogen
gas supply nozzles 50 may supply the nitrogen gas to the drying
vessel 10, for executing the rinsing under a nitrogen
atmosphere.
[0106] When the rinsing is terminated after a lapse of a prescribed
time, the drying liquid supply nozzles 40 start supplying the
drying liquid before pulling up substrates W (FIG. 12). The drying
liquid is supplied from the drying liquid supply nozzles 40 into
the cleaning bath 20 in the form of mist, as shown by arrows A12 in
FIG. 12. As described above, the drying liquid is made of only
silicone in this embodiment. The supplied water-insoluble silicone
having smaller specific gravity than water completely separates
from the de-ionized water and forms a thin liquid silicone layer on
the surface of the de-ionized water stored in the cleaning bath
20.
[0107] In this stage, the substrates W remain on the same positions
as those in the rinsing, while the de-ionized water is continuously
supplied from the de-ionized water supply nozzles 22 to overflow
the cleaning bath 20 from the upper end. While the silicone layer
formed on the surface of the de-ionized water also overflows the
cleaning bath 20 from the upper end along with the de-ionized
water, the drying liquid supply nozzles 40 continuously supply the
drying liquid and hence the silicone layer is regularly formed on
the surface of the de-ionized water stored in the cleaning bath
20.
[0108] After the silicone layer is formed on the surface of the
de-ionized water stored in the cleaning bath 20, the lifter LH
collectively pulls up the cleaned plurality of substrates W held by
the same (FIG. 13). Also in this stage, the de-ionized water is
continuously supplied from the de-ionized water supply nozzles 22
to overflow the cleaning bath 20 from the upper end at least while
the substrates W pass through the silicone layer. Further, the
drying liquid supply nozzles 40 continuously supply the drying
liquid as shown by arrows A13 and the ultrasonic vibration source
61 performs ultrasonic oscillation as shown by arrows A14 at least
while the substrates W pass through the silicone layer.
[0109] Also when the substrates W are pulled up, the drying liquid
is continuously supplied while the liquid layer of silicone flows
out from the upper end of the cleaning bath 20 along with the
de-ionized water, and hence the silicone layer is regularly formed
on the surface of the de-ionized water stored in the cleaning bath
20. Therefore, the plurality of substrates W pulled by the lifter
LH pass through the silicon layer formed on the surface of the
de-ionized water. Further, the ultrasonic vibration source 61
supplies ultrasonic vibration to the de-ionized water stored in the
cleaning bath 20, the silicone layer formed on the surface of the
de-ionized water and the pulled-up substrates W through the
propagation water 62.
[0110] FIG. 16 illustrates the pulled-up substrates W passing
through the silicone layer. A liquid silicone layer SL is formed on
the surface of de-ionized water DI stored in the cleaning bath 20.
The substrates W are pulled upward as shown by arrow A16 in FIG.
16. Thus, the substrates W pass through the silicone layer SL
successively from the upper end. When the substrates W are present
in the de-ionized water DI, the surfaces thereof are in contact
with the water, as a matter of course. When the substrates W pass
through the silicone layer SL, the liquid silicone forming the
silicone layer SL adheres to the surfaces of the substrates W in
place of moisture having been in contact therewith.
[0111] When the substrates W are pulled up, the ultrasonic
vibration source 61 supplies ultrasonic vibration as shown by
arrows A14 in FIG. 16. This ultrasonic vibration is propagated also
to boundary portions between the silicone layer SL, the de-ionized
water DI and the substrates W, to contribute to separation of the
water layer which is in contact with the surfaces of the substrates
W. In other words, the ultrasonic vibration from the ultrasonic
vibration source 61 prompts replacement of the liquid silicone with
the moisture having been in contact with the surfaces of the
substrates W.
[0112] Thus, the moisture having been in contact with the surfaces
of the substrates W is completely replaced with silicone, so that
only the liquid silicone adheres to the surfaces of the substrates
W exposed in the air (the surfaces of the substrates W located
above the silicone layer SL in FIG. 16).
[0113] The moisture separated by the aforementioned replacement
floats in the silicone layer SL as a number of fine droplets, and
the replacement efficiency with silicone is reduced if the quantity
of such fine droplets is excessively increased. According to the
third embodiment, however, the up-flow treatment is continuously
performed also when pulling up the substrates W at least while the
substrates W pass through the silicone layer SL as described above,
and the silicone layer SL gradually flows out from the upper end of
the cleaning bath 20 to flow into the collecting part 24.
Therefore, the fine droplets floating in the silicone layer SL are
successively discharged from the cleaning bath 20. Thus, the
quantity of the fine droplets floating in the silicone layer SL is
suppressed below a constant level, for maintaining the replacement
efficiency with the silicone.
[0114] When the lifter LH completely separates the substrates W
from the cleaning bath 20, the drying liquid supply nozzles 40 stop
supplying the drying liquid while the nitrogen gas supply nozzles
50 supply nitrogen gas or nitrogen gas heated by the heater 57
(FIG. 14). Thus, the inactive nitrogen gas supplied from the
nitrogen gas supply nozzles 50 substitutes for the atmosphere in
the drying vessel 10 while the silicone adhering to the substrates
W vaporizes. Particularly when heated nitrogen gas is sprayed
toward the substrates W, vaporization of the silicone is prompted
for reducing the drying time. In this stage, the ultrasonic
vibration source 61 stops ultrasonic oscillation while the
de-ionized water supply nozzles 22 stop supplying the de-ionized
water, for discharging the used de-ionized water and silicone from
the cleaning bath 20.
[0115] After the silicone adhering to the substrates W completely
vaporizes, the nitrogen gas supply nozzles 50 stop supplying the
nitrogen gas, and the lid of the drying vessel 10 is opened to
discharge the dried substrates W from the apparatus (FIG. 15). The
serial drying treatment of the substrates W is terminated in the
aforementioned manner.
[0116] As hereinabove described, the substrate dryer according to
the third embodiment forms the silicone layer on the surface of the
de-ionized water stored in the cleaning bath 20 for passing the
cleaned substrates W through the silicone layer thereby separating
moisture having been in contact with the surfaces of the substrates
W and replacing the same with the low-molecular silicone. Then, the
low-molecular silicone adhering to the surfaces of the substrates W
is vaporized after the replacement, thereby drying the substrates
W. The silicone, also employed for cosmetics or the like, is a
material applying only light load to the environment and causing no
problem such as disruption of the ozone layer or global warming,
which requires no specific treatment in disposal. Thus, increase of
the cost required for the drying treatment can be suppressed.
[0117] In addition, the low-molecular silicone having small surface
tension has higher permeability than IPA, as described above. The
low-molecular silicone can readily substitute for moisture also in
the recent refined.multidot.complicated device structure
particularly in a portion such as a hole having a large aspect
ratio. Therefore, the drying method employing the low-molecular
silicone exhibits excellent dryability also in the recent
refined.multidot.complicated device structure, and hardly causes
the problem of a water mark resulting from adhering moisture while
preventing the substrates W from adhesion of particles.
[0118] Further, the low-molecular silicone having small latent heat
of vaporization has a higher drying speed than IPA. Therefore, the
drying method employing the low-molecular silicone can reduce the
time required for drying as compared with the case of employing
IPA, improve the throughput, further suppress formation of a water
mark resulting from adhering moisture, and more effectively inhibit
the substrates W from adhesion of particles.
[0119] According to the third embodiment, the substrates W are
passed through the silicone layer formed on the surface of the
de-ionized water stored in the cleaning bath 20 for replacing
moisture having been in contact with the surfaces thereof with
silicone, whereby the moisture in contact with the main surfaces of
the substrates W is replaced with the silicone with no exposure to
the outside air, and formation of a water mark can be more
effectively suppressed.
[0120] In the third embodiment, further, the ultrasonic vibration
source 61 generates ultrasonic vibration for prompting separation
of layers of water having been in contact with the surfaces of the
substrates W, thereby further improving the replacement efficiency
with the silicone.
[0121] In addition, the de-ionized water supply nozzles 22 supply
the de-ionized water to the cleaning bath 20 at least while the
substrates W pass through the silicone layer for continuously
discharging the de-ionized water and the silicone layer from the
upper end of the cleaning bath 20 while the drying liquid supply
nozzles 40 continuously supply a new drying liquid to the cleaning
bath 20 in the third embodiment, whereby moisture separated by
replacement and floating in the silicone layer as droplets is
successively discharged from the cleaning bath 20 and a new
silicone layer is formed on the surface of the de-ionized water
stored in the cleaning bath 20, for maintaining the high
replacement efficiency with the silicone.
[0122] Further, the water-insoluble silicone completely separates
from water, to cause no Marangoni convection on the interface
between the silicone layer and the de-ionized water. Thus, no
problem such as transfer of particles results from a Marangoni
convection.
[0123] While the third embodiment of the present invention has been
described, the present invention is not restricted to the
aforementioned example. While the drying liquid vessel 41 stores
only the liquid low-molecular silicone for preparing the drying
liquid only from the silicone in the third embodiment, for example,
the drying liquid vessel 41 may alternatively store a mixed
solution of liquid low-molecular silicone and a water-soluble
solvent for preparing the drying liquid. The water-soluble solvent
can be prepared from alcohol such as IPA, acetone, ketone,
carboxylic acid or the like, for example. The content of the
water-soluble solvent in the mixed drying liquid must be not more
than 10 volume %. If the content of the water-soluble solvent in
the mixed drying liquid exceeds 10 volume %, the ratio of the
silicone in the mixed drying liquid is so reduced that the
aforementioned effect resulting from employment of silicone is hard
to attain and a specific problem (a problem of disposal or the
like) results from employment of IPA or the like. Such a problem
hardly arises when the content of the water-soluble solvent in the
mixed drying liquid is not more than 10 volume %.
[0124] While the substrate dryer according to the third embodiment
is also the so-called batch-system apparatus collectively treating
the plurality of substrates W, the technique of the third
embodiment is also applicable to the so-called sheet-feed apparatus
treating the substrates W one by one.
[0125] While the invention has been shown and described in detail,
the foregoing description is in all aspects illustrative and not
restrictive. It is therefore understood that numerous modifications
and variations can be devised without departing from the scope of
the invention.
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