Ex parte Leenaars et al.

Board of Patent Appeals and Interferences

Jul 22, 1997

07914654 (B.P.A.I. Jul. 22, 1997)

Application for patent filed July 15, 1992. According1
to applicants, this application is a continuation of
Application 07/701,295, filed May 13, 1991, now abandoned,
which is a continuation of Application 07/467,718, filed
January 19, 1990, now abandoned.
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today (1)
was not written for publication in a law journal and (2) is
not binding precedent of the Board.
Paper No. 32
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte ADRIAAN F.M. LEENAARS,
and JACQUES J. VAN DEKEL
_____________
Appeal No. 94-3000
Application 07/914,6541
______________
ON BRIEF
_______________
Before KIMLIN, WEIFFENBACH and PAK, Administrative Patent
Judges.
PAK, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 94-3000
Application 07/914,654
2
Adrian F.M. Leenaars et al. (Appellants) appeal from the
examiner's final rejection of claims 17 through 23, 25 and 26,
which are all the claims remaining in the application.
The subject matter on appeal is directed to a process for
cleaning and drying substrates, such as silicon wafers, and an
apparatus for carrying out the process. Claims 21 and 25 are
representative of the subject matter on appeal and read as
follows:
21. An apparatus for treating substrates comprising
(a) container means for containing a bath of a liquid,
(b) holding means for immersing at least one substrate
into said bath,
(c) lifting means for lifting said at least one substrate
from said bath at a speed such that substantially all of said
liquid remains in said bath, said lifting means including
knife-shaped means for pushing said at least one substrate
upwardly at a lowest portion of said at least one substrate,
(d) gripping means for gripping dried parts of said at
least one substrate above said bath after withdrawal from said
bath, and
(e) means having outlet nozzles for passing vapor of an
organic solvent directly onto said at least one substrate
immediately upon leaving said bath, said vapor being free of
condensation of said at least one substrate, said organic
solvent being chosen from a group of organic solvents which
are miscible with a liquid which is the same as said liquid
Appeal No. 94-3000
Application 07/914,654
3
used in said bath, and said organic solvent forming with said
liquid a mixture having a surface tension lower than that of
said liquid alone,
wherein contaminants and drying marks are substantially
eliminated from said at least one substrate.

25. A method of treating substrates comprising the steps
of
(a) immersing at least one substrate into a bath of a
liquid,

(b) maintaining said at least one substrate in said bath
for a given time period,
(c) withdrawing said at least one substrate from said
bath at a speed such that substantially all of said liquid
remains in said bath, and
(d) directly contacting said at least one substrate with
a vapor of an organic solvent immediately upon leaving said
bath, said vapor being free of condensation on said at least
one substrate upon withdrawing said at least one substrate
from said bath, said organic solvent being chosen from a group
of organic solvents which are miscible with a liquid which is
the same as said liquid used in said bath, and said organic
solvent forming with said liquid a mixture having a surface
tension lower than that of said liquid alone,
wherein contaminants and drying marks are substantially
eliminated from said at least one substrate by said step (d).
The references of record relied upon by the examiner are:
Appeal No. 94-3000
Application 07/914,654
4
Steck 4,722,752 Feb. 2, 1988
(Filed June 16, 1986)
Kremer 4,828,751 May 9, 1989
(Filed Aug. 28, 1987)
Kurokawa et al (Kurokawa) 5,105,556 Apr. 21, 1992
(Filed Aug. 9, 1988)

Claims 17 through 23, 25 and 26 stand rejected under 35
U.S.C. § 103 as unpatentable over the combined disclosures of
Steck, Kremer and Kurokawa.
We have carefully reviewed the entire record, including
each of the arguments and comments advanced by appellants and
the examiner in support of their respective positions. This
review leads us to conclude that only the examiner's rejection
of process claims 17 through 20, 25 and 26 is well-founded.
Accordingly, we shall affirm the rejection of process claims
17 through 20, 25 and 26, but reverse the rejection of
apparatus claims 21 through 23. Our reasons for these
determinations follow.
At the outset, we note appellants' argument that "each of
the claims [is] separately patentable over the prior art.."
See Brief, page 5. To the extent appellants have argued the
limitations of each claim separately consistent with 37 CFR
Appeal No. 94-3000
Application 07/914,654
5
§ 1.192 (c)(7)(1993), we shall treat the claims separately.
The examiner has rejected process claims 17 through 20,
25 and 26 under § 103 as unpatentable over the combined
disclosures of Steck, Kremer and Kurokawa. As indicated by
the examiner at pages 2 and 3 of the answer, the Steck
reference discloses a method for rinsing and drying
substrates, such as silicon wafers. The silicon wafers are
initially submerged in a tank containing high purity, hot
deionized water. See Steck, column 2, lines 7-9. The hot
deionized water flowing in a laminar flow removes particulate
contaminants. See Steck, column 1, lines 54-60 and column 2,
lines 9-12. The resulting wafers are efficiently dried by
slowly withdrawing them from the tank. See Steck, column 4,
lines 4-15 and column 2, lines 19-21.
The examiner, however, recognized that Steck does not
disclose directly contacting the withdrawn wafers with a vapor
of an organic solvent during the drying step. See answer,
page 3. This recognition led to reliance on the Kremer and
Kurokawa references. The Kremer reference discloses a
conventional wafer drying technique employing vapor dryers
utilizing isopropyl alcohol as a drying agent after cleaning
Appeal No. 94-3000
Application 07/914,654
6
the wafer with deionized water. See column 1, lines 19-28.
This conventional drying technique is said to create "a
significant amount of waste over the period of a month, for
example, and also a significant fire hazard." See column 1,
lines 28-30.
Similarly, the Kurokawa reference discloses three
different conventional drying techniques which are known to
remove water drops on the wafers. See column 1, lines 22-37.
One of the conventional drying techniques involves employing
vapor of organic solvent, such as isopropyl alcohol (IPA).
See column 1, lines 38-48. According to column 2, lines 6-12
of Kurokawa, "although the IPA vapor drying method is less
sensitive to the influence of impurities in the ultra-pure
water since the water that is used in the washing is replaced
with IPA, it has the problem of adhesion of impurities in the
IPA due to the dispersion of IPA mist and the problem of
replacement between the IPA and the water."
At issue is, therefore, whether the use of a conventional
IPA vapor drying method to dry the water-treated wafers
withdrawn from a deionized water containing tank as taught by
Appeal No. 94-3000
Application 07/914,654
7
Steck would have been obvious to one of ordinary skill in the
art.
We find ourselves in agreement with the examiner that it
would have been obvious to one of ordinary skill in the
relevant art to employ the conventional vapor drying method in
the drying step of Steck with the reasonable expectation of
obtaining dried silicon wafers (dried of the water to less
than 3 nm) having reduced water spots and drops in an
effective manner. In reaching this conclusion, we find that
the advantages of employing the conventional vapor drying
technique far outweigh the disadvantages of employing the
same. As can be seen from the disclosures of both the Kremer
and the Kurokawa references, the conventional vapor drying
technique is one of the few, which is commercially available
for the purpose of drying the wafers after cleaning them with
water. It, like the drying technique of Steck (slowly
withdrawing wafers from a water tank), is useful for removing
water spots and drops from the wafers. When the drying
technique of Steck is used in conjunction with this
conventional vapor drying technique, one of ordinary skill in
the relevant art would have reasonably expected to obtain an
Appeal No. 94-3000
Application 07/914,654
According to page 617 of Grant & Hackh's Chemical2
Dictionary, Fifth Edition, 1987 (attached herewith), vapor is
"[a] gas, especially from a substance that at ordinary
temperature is a solid or liquid".
8
additive drying effect. That is, one of ordinary skill in the
art would have recognized that the reduced amount of the IPA
vapor can be employed during the drying step of Steck to
obtain the enhanced effect of removing water spots and drops
on the wafers, with the minimum negative effect associated
with using a large volume of the IPA vapor.
Appellants appear to argue at page 1 of the reply brief
that
a vapor of the organic solvent referred to by the Kremer and
the Kurokawa references is not free of condensation. We,
however, note that the term "vapor" by definition means free
of conden-sation. Appellants simply have not proffered any2
objective evidence to demonstrate that the IPA vapor used in
the conven-tional vapor drying technique contains
condensation. See In re Greenfield, 571 F.2d 1185, 1189, 197
USPQ 227, 230 (CCPA 1978) (Counsel's arguments and conclusory
statements must be supported by objective evidence and cannot
take the place of such evidence).
Appeal No. 94-3000
Application 07/914,654
9
Appellants also appear to argue that the IPA (isopropyl
alcohol) vapor does not have the claimed properties, including
miscibility. Appellants, however, acknowledge that the
claimed 2-propanol vapor has such properties. See the
dependent claims. It then follows that the isopropyl alcohol
vapor (which is otherwise known as 2-propanol vapor) of the
Kremer and the Kurokawa references, has the claimed
properties.
Further, appellants appear to argue that the preferred
embodiments of the Kremer and Kurokawa references are directed
to employing solvents having different properties than those
claimed for the purposes of cleaning and drying silicon
wafers. However, we cannot limit our focus to the preferred
embodiments of the prior art references only. We need to
consider all the prior art references in their entirety. In
re Boe, 355 F.2d 961, 965, 148 USPQ 507, 510 (CCPA 1966)("we
concluded... the claimed invention obvious to those of
ordinary skill in the art despite the fact that the art
teachings relied upon in all three cases were phrased in terms
of a non-preferred embodiment..."). Upon taking into
consideration the non-preferred embodiments of the Kremer and
Appeal No. 94-3000
Application 07/914,654
10
the Kurokawa references as discussed above, we determine, as
indicated supra, that it would have been obvious to employ the
conventional IPA vapor drying method in the drying step of
Steck.
Moreover, appellants appear to argue that the showing in
the Table at page 11 of the specification establishes the
criticality of the claimed particular solvents over other
solvents. Appellants, however, do not refer to any comparison
between the closest prior art, a conventional drying process
employing 2-propanol vapor, and the claimed invention. In re
Merchant, 575 F.2d 865, 868, 197 USPQ 785, 787 (CCPA 1978).
Nor do appellants demonstrate that the showing in the Table is
commensurate in scope with the claims to which it pertains.
In re Dill, 604 F.2d 1356, 1361, 202 USPQ 805, 808 (CCPA
1979). While the showing is limited to silicon wafers treated
with specific steps and solvents under particular conditions,
none of the claims is so limited.
Under the circumstances recounted above, it is our
determination that the evidence of record for and against
obviousness, on balance, weighs most heavily in favor of an
obviousness conclusion. Accordingly, we shall sustain the
Appeal No. 94-3000
Application 07/914,654
11
examiner's rejection of process claims 17 through 20, 25 and
26.
The rejection of apparatus claims 21 through 23 as being
unpatentable over the disclosures of the Steck, Kremer and
Kurokawa references, however, is on a different footing.
Appellants state that none of the references relied upon by
the examiner renders the claimed lifting means obvious or
anticipated. The lifting means recited in claim 21 read as
follows:
(c) lifting means for lifting said at least one
substrate from said bath at a speed such that
substantially all of said liquid remains in said
bath, said lifting means including knife-shaped
means for pushing said at least one substrate
upwardly at a lowest portion of said at least one
substrate,
We interpret this means-plus-function limitations as the
corresponding structure in the specification or equivalents
thereof. See, e.g., In re Donaldson Co. Inc., 16 F.3d 1189,
29 USPQ2d 1845 (Fed. Cir. 1994)(in banc); Laitram Corp v.
Rexnord, Inc., 939 F.2d 1533, 1536, 19 USPQ2d 1367, 1369 (Fed.
Cir. 1991) ("[t]he recitation of some structure in a means
plus function element does not preclude the applicability of
Appeal No. 94-3000
Application 07/914,654
12
section 112(6)"). According to pages 5, 6, 7 and 10 of the
specification, the lifting means is described as follows:
The invention further relates to an arrangement
for carrying out the method mentioned in the opening
paragraph, this arrangement being provided with a
lifting member for lifting the substrates above the
liquid and with means for gripping the dry
substrates above the liquid.
... On the lower side of the substrates, which
in the known arrangement are taken from the liquid,
a drop of liquid sticks. In order to avoid this,
the arrangement according to the invention is
provided with a knife-shaped member, which supports
the substrates when lifted from the liquid at those
parts of the substrates which are the last to leave
the liquid. The drops then flow away via the knife-
shaped member.
... Further, the arrangement comprises a
lifting member 15, which can be moved upwardly by
means of shafts 16, passing through the bottom 10 of
the bath 2 and which are driven by driving means not
shown. Thus, the substrates 1 can be slipped or
moved upwardly from the cassette 4 into the
auxiliary cassette 11.
... According to the invention, this knife-
shaped member 19 forms parts of the lifting member
15 and the substrates are lifted from the liquid by
the knife-shaped member 19. The knife-shaped member
19 is made, for example, of quartz glass and has an
apical angle of less than 100 . When the substrateso
are lifted from the liquid 3, the whole quantity of
liquid now flows away from the substrate via this
knife-shaped member 19.
Appeal No. 94-3000
Application 07/914,654
13
Thus, the lifting means is interpreted as including a
specifically placed structure consisting of a body connected
to shafts and a knife-shaped member made of quartz glass, with
an apical angle of less than 100E, or equivalents thereof.
However, we observe that the examiner has not explained, much
less proven, that such structure is described or would have
been suggested by any of the references relied upon by the
examiner. Thus, we are constrained to reverse the examiner's
rejection of apparatus claims 21 through 23.
The decision of the examiner is affirmed-in-part.
No time period for taking any subsequent action in
connection with this appeal may be extended under 37 CFR
1.136(a).
AFFIRMED-IN-PART
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
)
CAMERON WEIFFENBACH ) BOARD OF
PATENT
Appeal No. 94-3000
Application 07/914,654
14
Administrative Patent Judge ) APPEALS
) AND
)
INTERFERENCES
)
CHUNG K. PAK )
Administrative Patent Judge )
)
Appeal No. 94-3000
Application 07/914,654
15
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