Ex Parte Ikeda

Board of Patent Appeals and Interferences

Jun 28, 2002

09273541 (B.P.A.I. Jun. 28, 2002)

1 Application for patent filed March 22, 1999, which is a divisional of
Application 08/976,041, filed November 21, 1997, now abandoned, which claims
the foreign filing priority benefit under 35 U.S.C. § 119 of Japanese
Application No. 09-54116, filed February 21, 1997.
The opinion in support of the decision being entered today was not written
for publication and is not binding precedent of the Board.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 MASAYOSHI IKEDA
____________
Appeal No. 2001-1512
Application No. 09/273,5411
____________
HEARD: JUNE 11, 2002
____________
Before KRASS, BARRETT, and SAADAT, Administrative Patent Judges.
SAADAT, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal from the Examiner’s final
rejection of claims 4 and 5, which are all of the claims pending
in this application.
We reverse.
Appeal No. 2001-1512
Application No. 09/273,541
Page 2
BACKGROUND
Appellant’s invention is directed to a method of assessing
substrate temperature controllability in a substrate processing
apparatus. An inert cooling gas such as helium (He) is supplied
to a gap between the substrate and an electrostatic chucking
stage, which functions as a heat transfer gas and maintains the
substrate temperature constant during processing (specification,
page 2). In contrast with the conventional method of controlling
the cooling gas pressure by opening and closing a bypass valve,
Appellant’s invention controls the pressure by a flow rate based
on the difference between a measured pressure and a set value
(specification, page 7). The flow rate value corresponds to the
extend the cooling gas leaks out from the gap between the
substrate and the chucking stage (specification, page 13) and
indicates unsatisfactory state of chucking when the amount of
leakage is high (specification, page 14).
The only independent claim is reproduced as follows:
4. A method of assessing a substrate condition of a
substrate, comprising the steps of:
delivering a heat transfer gas to a control device
including an exhaust valve and a pressure control valve;
supplying a set pressure value to the pressure control
valve;
Appeal No. 2001-1512
Application No. 09/273,541
3
closing the exhaust valve so that all of the heat
transfer gas passing the pressure control valve is delivered
to a gap between the substrate and a substrate mounting
surface of a substrate holder;
measuring the pressure of the heat transfer gas which
is flowing in the gap between the substrate and the
substrate mounting surface of the substrate holder;
supplying the measured pressure to the pressure control
valve;
automatically controlling the flow rate of the heat
transfer gas with the pressure control valve on the basis of
a difference between the set pressure value and the measured
pressure such that the measured pressure of the heat
transfer gas becomes equal to the set pressure value and the
flow rate corresponds to a leakage rate of the heat transfer
gas; and
assessing a state of the gap between the substrate and
the substrate mounting surface on a basis of a comparison of
the heat transfer gas flow rate with a standard value.
The prior art references of record relied upon by the
Examiner in rejecting the appealed claims are:
Tezuka 4,771,730 Sep. 20, 1988
White 5,822,172 Oct. 13, 1998
(filed Jan. 7, 1997)
Claims 4 and 5 stand rejected under 35 U.S.C. § 103 as being
unpatentable over Tezuka in view of White.
We make reference to the answer (Paper No. 26, mailed
November 7, 2000) for the Examiner’s complete reasoning in
support of the rejection, and to the brief (Paper No. 25, filed
Appeal No. 2001-1512
Application No. 09/273,541
4
2 Paper No. 15, mailed April 4, 2000.
October 4, 2000) and the reply brief (Paper No. 28, filed January
2, 2001) for Appellant’s arguments thereagainst.
OPINION
To address the language of independent claim 4, the Examiner
relies on the teachings of Tezuka (col. 2, lines 35-44)
describing the delivery of a heat transfer gas to the interface
between the work [substrate] and the electrostatic chuck (final
rejection, page 2).2 The Examiner reasons that while Tezuka does
not specify closing the exhaust valve, the reference teaches
controlling of the cooling gas pressure by observing gage 19 and
manipulating valves 16 and 17 (col. 4, lines 44-47) and
therefore, would operate if the exhaust valve is closed (id.).
The Examiner also points to the teaching of Tezuka related to
control of flow rate and concludes that the “correspondence of
the flow rate to a leakage rate is inherent in this measurement
since the flow rate is claimed to be controlled only by pressure
measurement methods” (final rejection, page 3).
The Examiner further relies on White for teaching the
assessment of a state of the gap between the substrate and the
chuck by monitoring a different effect other than comparing the
Appeal No. 2001-1512
Application No. 09/273,541
5
heat transfer gas flow rate with a standard valve (final
rejection, pages 3 & 4). The Examiner supports this conclusion
by further stating (id.) that:
Although White et al. teaches monitoring a different effect
of the separation, one of ordinary skill would have realized
that any of the effects taught by White et al. could be
monitored and the apparatus of Tezuka already has a pressure
gauge and automatic control valve. [Emphasis added.]
Appellant argues that the mere fact that Tezuka may possibly
be operative with a closed exhaust valve and that the reference
inherently discloses the closing of the exhaust valve is based on
speculations unsupported by the disclosure of Tezuka or the
knowledge of one of ordinary skill in the art (brief, pages 12 &
13 and reply brief, pages 2-4). Additionally, Appellant argues
that controlling the cooling gas pressure of Tezuka would not
lead one of ordinary skill in the art to close the variable valve
17 (brief, page 14 and oral hearing). Appellant further
characterizes the Examiner’s reasoning that in the absence of
teaching away from closing the exhaust valve, Tezuka must teach
the closing of the exhaust valve, as improper shifting the burden
to Appellant to prove the contrary (brief, page 15).
Additionally, Appellant asserts that White does not disclose
or suggest automatically controlling gas flow rate for assessing
the gap between the wafer and the chuck (brief, page 17).
Appeal No. 2001-1512
Application No. 09/273,541
6
Appellant argues that White merely detects separation between a
wafer and the chuck by monitoring the current flow into the
electrostatic clamp (id.). In particular, Appellant points to
the constant cooling gas flow rate of White and indicates that
there would be no reason to assess the state of the gap based on
comparing the measured gas flow rate with a standard value
(brief, page 18 and reply brief, pages 5-8).
In response, the Examiner indicates that absent contrary
teachings in Tezuka, one having average skill in the art would
have understood the term “manipulating” to include “setting the
valve to any and all positions available to the valve, including
open, closed, and all positions in between” (answer, page 3).
With respect to the teachings of White, the Examiner further
asserts that White provides reasons for monitoring incorrect
alignment that includes “prevention of excessive outgassing into
the chamber and accurate positioning of the substrate wafer”
(answer, page 5).
In rejecting claims under 35 U.S.C. § 103, the Examiner
bears the initial burden of presenting a prima facie case of
obviousness. See In re Rijckaert, 9 F.3d 1531, 1532, 28 USPQ2d
1955, 1956 (Fed. Cir. 1993). The conclusion that the claimed
subject matter is obvious must be supported by evidence, as shown
Appeal No. 2001-1512
Application No. 09/273,541
7
by some objective teaching in the prior art or by knowledge
generally available to one of ordinary skill in the art that
would have led that individual to combine the relevant teachings
of the references to arrive at the claimed invention. See In re
Fine, 837 F.2d 1071, 1074, 5 USPQ2d 1596, 1598 (Fed. Cir. 1988).
Our reviewing court requires this evidence in order to establish
a prima facie case. In re Piasecki, 745 F.2d 1468, 1471-72, 223
USPQ 785, 787-88 (Fed. Cir. 1984); In re Cofer, 354 F.2d 664,
668, 148 USPQ 268, 271-72 (CCPA 1966). However, “the Board must
not only assure that the requisite findings are made, based on
evidence of record, but must also explain the reasoning by which
the findings are deemed to support the agency’s conclusion.” In
re Lee, 277 F.3d 1338, 1344, 61 USPQ2d 1430, 1434 (Fed. Cir.
2002).
A review of Tezuka reveals that the reference relates to a
vacuum processing apparatus in which a heat transfer gas is
introduced in the gap between an electrostatic chuck and a
substrate placed on the chuck (col. 2, lines 35-44). We find
that Tezuka provides the cooling gas to the gap at a desired flow
rate. The specific passage in Tezuka that relates to controlling
of the pressure of the cooling gas (col. 4, lines 44-47), as
relied upon by the Examiner and argued by Appellant, states that:
Appeal No. 2001-1512
Application No. 09/273,541
8
The pressure of this cooling gas is controlled at a specific
desired value by observing the indication of the pressure
gage 19 and manipulating the flow rate control valve 16 and
the variable valve 17.

Thus, both valves 16 and 17 are constantly adjusted to control
the flow rate at a desired level that shows on gage 19. However,
we find nothing in Tezuka that teaches or suggests that the
exhaust valve (variable valve 17) is closed after the cooling gas
is delivered to the gap between the substrate and the chuck. In
fact, both valves 16 and 17 are manipulated to maintain the flow
of the cooling gas at a specific rate. The reference contains no
teaching or suggestion of “closing the exhaust valve so that all
of the heat transfer gas passing the pressure control valve is
delivered to a gap between the substrate and a substrate mounting
surface of a substrate holder,” as recited in Appellant’s claim
4. Although variable valve 17 may be capable of being closed at
some point while the gas pressure is being controlled, the
Examiner does not point to a specific suggestion or reason, and
we do not find any in Tezuka to that effect, for closing the
variable valve 17 after delivering the cooling gas. See In re
Mills, 916 F.2d 680, 682, 16 USPQ2d 1430, 1432 (Fed. Cir. 1990)
("While Mathis’ apparatus may be capable of being modified to run
the way Mills’ apparatus is claimed, there must be a suggestion
Appeal No. 2001-1512
Application No. 09/273,541
9
or motivation in the reference to do so.”). See also In re
Fritch, 972 F.2d 1260, 1266 n.14, 23 USPQ2d 1780, 1783-84 n.14
(Fed. Cir. 1992), citing In re Gordon, 733 F.2d 900, 902, 221
USPQ 1125, 1127 (Fed. Cir. 1984) (“The mere fact that the prior
art may be modified in the manner suggested by the Examiner does
not make the modification obvious unless the prior art suggested
the desirability of the modification").
Moreover, to assert that the cooling gas flow rate
inherently corresponds to the leakage rate at the wafer-chuck
interface when valve 17 is closed, places the initial burden on
the Examiner to establish that “the missing descriptive matter is
necessarily present in the thing described in the reference, and
that it would be so recognized by person of ordinary skill.” In
re Robinson, 169 F.3d 743, 745, 49 USPQ2d 1949, 1950-1951 (Fed.
Cir. 1999), citing Continental Can Co. v. Monsanto Co., 948 F.2d
1264, 1269, 20 USPQ2d 1746, 1749 (Fed. Cir. 1991) (inherency may
not be established by probabilities or possibilities or by the
mere fact that a certain thing may result for a given set of
circumstances). In this case, we agree with Appellant that both
valves 16 and 17 are manipulated or continuously controlled
(brief, page 14), since the Examiner provides no showing that
Appeal No. 2001-1512
Application No. 09/273,541
10
valve 17 is closed and the gas flow rate necessarily corresponds
to the leakage rate at the wafer-chuck interface.
Turning now to White, we find that the reference is directed
to a similar vacuum processing apparatus that includes an
electrostatic chuck and a cooling gas flowing in the gap between
the wafer and the chuck. However, as also indicated by Appellant
(brief, page 18), White introduces a constant flow of cooling gas
at the interface between the workpiece (wafer) and the platen
(chuck) having a controlled flow rate of approximately 0.25 sccm
(col. 5, lines 16-20). White’s constant flow rate of the cooling
gas is comparable to Tezuka’s desired flow rate which is
indicated by pressure gage 19. We further find that White
teaches that the tightness of contact between the wafer and the
chuck may be compromised if the wafer is separated from the chuck
due to incorrect placement of the wafer or the presence of
particles (generated from the process) landing on the chuck (col.
10, lines 20-44). White also indicates that such separation
decreases capacitance between the wafer and the electrode on the
chuck and causes the current flow to the electrodes of the
electrostatic chuck be reduced (id.). Therefore, White keeps the
cooling gas flow at a constant level without corresponding the
flow rate to the leakage rate from the gap between the wafer and
Appeal No. 2001-1512
Application No. 09/273,541
11
the chuck. White, in fact, assesses the state of the placement
of the wafer or separation of the wafer from the chuck by
measuring a reduction in the electric current flow not by the
difference between the flow rate of the cooling gas and a
predetermined value.
Assuming, arguendo, that it would have been obvious to
combine White’s method of assessing the wafer-chuck contact by
measuring the current with the apparatus of Tezuka, as held by
the examiner, Tezuka would still not disclose the claimed steps
of closing the exhaust valve so that all of the cooling gas
passing through valve 16 is delivered to the gap between the
wafer and the chuck. In that regard, Tezuka only supplies what
appears to be a constant flow of cooling gas controlled by
manipulating two valves while White monitors changes in the gap
between the wafer and the chuck by measuring the current flow to
the electrostatic chuck. Accordingly, as the Examiner has failed
to establish a prima facie case of obviousness, the rejection of
claim 4, as well as claim 5 which depends therefrom, under 35
U.S.C. § 103 over Tezuka and White is not sustained.
Appeal No. 2001-1512
Application No. 09/273,541
12
CONCLUSION
In view of the foregoing, the decision of the Examiner
rejecting claims 4 and 5 under 35 U.S.C. § 103 is reversed.
REVERSED
ERROL A. KRASS )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
LEE E. BARRETT ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
MAHSHID D. SAADAT )
Administrative Patent Judge )
MDS/ki
Appeal No. 2001-1512
Application No. 09/273,541
13
Burns, Doane, Swecker & Mathis
Post Office Box 1404
Alexandria, VA 22313-1404