Ex Parte Sinha et al

Board of Patent Appeals and Interferences

Mar 31, 2010

10914947 (B.P.A.I. Mar. 31, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________________

Ex parte ASHOK K. SINHA, DANIEL J. HOFFMAN,
and JOHN P. HOLLAND
____________________

Appeal 2009-006372
Application 10/914,947
Technology Center 1700
____________________

Decided: March 31, 2010
____________________

Before MICHAEL P. COLAIANNI, LINDA M. GAUDETTE, and
JEFFREY B. ROBERTSON, Administrative Patent Judges.

COLAIANNI, Administrative Patent Judge.

DECISION ON APPEAL
This is a decision on an appeal under 35 U.S.C. § 134 from the
Examiner's final rejection of claims 1 through 9, 21 through 29, and 31
through 37. Claim 30 stands withdrawn from consideration by the
Examiner. We have jurisdiction pursuant to 35 U.S.C. § 6.
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We AFFIRM.
STATEMENT OF THE CASE
The subject matter on appeal is directed to a plasma reactor. Claim 1
is illustrative:
1. A plasma reactor for processing a substrate, comprising:
a reactor chamber having a chamber wall and containing a substrate
support;

an electrode overlying and spaced apart from the substrate support;

one or more plasma sources capable of maintaining plasma in one or
more toroidal paths using a first frequency; and

one or more RF power generators, where said one or more RF power
generators supplies power at a second frequency to said electrode, where the
first frequency is different from the second frequency.

As evidence of unpatentability of the claimed subject matter, the
Examiner relies upon the following references:
Takagi 4,539,068 Sep. 3, 1985
Collins '501 5,556,501 Sep. 17, 1996
Trow 5,824,607 Oct. 20, 1998
Nowak 5,865,896 Feb. 2, 1999
Tomoyasu 5,900,103 May 4, 1999
Wikuramanayaka JP 2002-246368 Aug. 30, 20021
Collins '420 6,545,420 B1 Apr. 8, 2003
Hanawa 6,551,446 B1 Apr. 22, 2003

1 Our reference to Wikuramanayaka is to the translation thereof prepared for
the U.S. Patent and Trademark Office by FLS, Inc. (PTO 09-0327, October
2008).

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Georgieva, V. et al., "Numerical study of Ar/CF4/N2 discharges in single-
and dual-frequency capacitively coupled plasma reactors," Journal of
Applied Physics, Vol. 94, No. 6, pp. 3748-3756, (Sep. 15, 2003) (hereinafter
"Georgieva").

The Examiner maintains the following rejections:
1) Claims 1-9, 21-29, 31, and 34-37 under 35 U.S.C. § 103(a) as
unpatentable over Hanawa in view of Nowak, Trow, or Collins '501;
2) Claim 32 under 35 U.S.C. § 103(a) as unpatentable over Hanawa,
in view of Nowak, Trow, or Collins '501, and further in view of Tomoyasu
or Takagi;
3) Claim 33 under 35 U.S.C. § 103(a) as unpatentable over Hanawa,
in view of Nowak, Trow, or Collins '501, and further in view of
Wikuramanayaka or Georgieva; and
4) Claims 35-37 under 35 U.S.C. § 103(a) as unpatentable over
Hanawa in view of Collins '420.

REJECTIONS (1)-(3)
With respect to rejection (1), Appellants' arguments focus on claims
1 and 23. Accordingly, we address Appellants' arguments regarding the
rejection with respect to claims 1 and 23 only. See 37 C.F.R. § 41.37(c)(1)
(vii) (2009).
With respect to rejections (2) and (3), Appellants do not advance any
specific argument regarding either of these rejections. Instead, Appellants
refer to arguments made in connection with rejection (1). (Br. 10-12).
Therefore, the Examiner's rejections of dependent claims 32 and 33 in
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rejections (2) and (3), respectively, stand or fall with respect to our analysis
of independent claims 1 and 23 in rejection (1).

ISSUES
Did the Examiner err in finding that Hanawa does not teach away or
determining that the plasma reactor having one or more RF power generators
supplying power to an electrode as required by claims 1 and 23 would have
been obvious within the meaning of 35 U.S.C. § 103(a)? We decide these
issues in the negative.

FINDINGS OF FACT (FF)
1. Appellants do not specifically dispute the Examiner's finding that
even though the abstract of Collins et al. '501 refers to
controlling the cathode sheath voltage independent of
the density with respect to the wafer support, one of
ordinary skill in the art would have understood that
such principles could equally be applied to the top
electrode since the top electrode is being supplied with
an independent RF power supply from the RF power
supply that controls the plasma density.

(Compare Ans. 12 with Br. 4-12) (emphasis added). In addition, Appellants
do not specifically dispute the Examiner's reason for combining Hanawa and
Collins '501, which is to add "RF power generators of . . . Collins et al. [to
Hanawa’s conductive showerhead] because . . . parameters such as the
cathode sheath voltage can be controlled independent of density and process
control can be . . . improved." (Compare Ans. 5 with Br. 4-12).

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2. Hanawa teaches that
[t]he conductive showerhead 210 constricts the plasma current path . .
. because a plasma sheath is formed around the portion of the
showerhead surface immersed in the plasma. The sheath has a greater
impedance to the plasma current than the space between the wafer 120
and the showerhead 210.

(Hanawa, col. 8, ll. 60-65). Hanawa also teaches that "[t]he thickness of
the sheath (with RF bias applied to the workpiece or other electrode) is
greater where the electric field is concentrated over a small area, such as
the wafer, and is less in other locations." (Hanawa, col. 7, ll. 11-14).
3. Hanawa teaches that the "RF power in the vicinity of the wafer-to-
ceiling gap . . . is relatively low." (Hanawa, col. 7, ll. 41-44).

PRINCIPLES OF LAW
“[A]nalysis [of whether the subject matter of a claim would have been
obvious] need not seek out precise teachings directed to the specific subject
matter of the challenged claim, for a court can take account of the inferences
and creative steps that a person of ordinary skill in the art would employ.”
KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 418 (2007).
"A reference may be said to teach away when a person of ordinary
skill, upon reading the reference, would be discouraged from following the
path set out in the reference, or would be led in a direction divergent from
the path that was taken by the applicant." In re Gurley, 27 F.3d 551, 553
(Fed. Cir. 1994).

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ANALYSES AND CONCLUSIONS
Appellants argue that "none of the cited references provide the
teaching or suggestion asserted by the Examiner for modifying Hanawa in
the manner asserted by the Examiner." (Br. 6). Specifically, Appellants
argue that "none of the three references teaches or suggests controlling
cathode sheath voltage independent of the density via applying RF power to
the upper electrode of the domed reactor." (Br. 6). Appellants also argue
that
Collins teaches applying RF power for controlling
cathode sheath voltage to the wafer support cathode,
and not to the upper electrode, as the Examiner asserts.
Accordingly, the combination of the cited references
would result in the apparatus of Hanawa having RF
power coupled to a wafer support cathode, and not to an
electrode overlying and spaced apart from the substrate
support.
Thus, the combination of the cited art fails to result in
[the claimed invention].

(Br. 6). Appellants, however, do not specifically dispute the Examiner's
finding that one of ordinary skill would have understood that Collins '501's
teaching of an RF power supply for controlling the cathode sheath voltage
with respect to a wafer support could also be applied to a top electrode (FF
1). In addition, Appellants do not specifically dispute the Examiner's reason
for combining Hanawa with Collins '501, which is to add "RF power
generators of . . . Collins et al. [to Hanawa’s conductive showerhead]
because . . . parameters such as the cathode sheath voltage can be controlled
independent of density and process control can be . . . improved." (FF 1).
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Appellants also argue that Hanawa teaches away from the
modification proposed by the Examiner. Specifically, Appellants argue that
Hanawa teaches that the ceiling 110 (and the gas
distribution plate 210) should not be coupled to RF
power because the ceiling 110 provides a reliable
electric potential or ground reference across the entire
plane of the pedestal and that applying RF power in the
vicinity of the wafer-to-ceiling gap will increase the
likelihood of device damage from RF fields.

(Br. 8). In addition, Appellants argue that

Hanawa teaches that it is not beneficial to have a lot of
RF power absorbed within the narrow wafer-to-ceiling
gap, so that it is greatly concentrated in that region, and
that the benefit of enhancing process performance
through a dramatic reduction in volume is specifically
achieved because the concentration of RF power is
limited in the wafer-to-ceiling gap by the long toroidal
path of Hanawa. Thus, one skilled in the art would not
be motivated to combine the teachings of Hanawa with
those of the cited secondary references (Nowak or Trow
or Collins) because such a combination would result in
increased RF power in the wafer-to-ceiling gap.
Hanawa clearly teaches away from that limitation.

(Br. 9-10).

In addition, Appellants also argue that

if Hanawa was modified to apply RF power to the gas
distribution plate in the manner asserted by the
Examiner, the modification would render Hanawa
unsatisfactory for its intended purpose - which is, at
least in part, to provide a reactor having reduced RF
fields in the process region proximate the wafer.

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(Br. 8-9).
With respect to Appellants' teaching away arguments, nowhere does
Hanawa discourage having any RF power in the vicinity of the wafer-to-
ceiling gap. Gurley, 27 F.3d at 553. To the contrary, Hanawa teaches that
there is "relatively low" RF power in the vicinity of the wafer-to-ceiling gap.
(FF 3).
Contrary to Appellants’ arguments that the art teaches away and
modifying Hanawa would render it unsatisfactory for its intended purpose,
since Hanawa teaches that the RF power be kept "relatively low" in the
vicinity of the wafer to ceiling gap, it would have been within the skill level
of one of ordinary skill in the art to adjust the RF power to Hanawa’s
showerhead to obtain the desired sheath thickness while at the same time
maintaining a “relatively low” RF power in order to ensure that the device is
free from damage. KSR, 550 U.S. at 418. Thus, the combination of the cited
prior art references would not render Hanawa unsatisfactory for its intended
purpose because one of ordinary skill in the art could adjust the RF power to
be "relatively low" while at the same time obtaining a desired sheath
thickness. Accordingly, Appellants' argument is unpersuasive of reversible
error.
Appellants, referencing Hanawa's column 7, lines 37-45 and column
8, lines 26-37, argue that
Hanawa teaches that it is advantageous to use
inductively coupled RF plasma over a long toroidal path
such that RF power in the vicinity of the wafer-to-
ceiling gap may be kept low, and thus reduce device
damage. Thus, the Appellants maintain that Hanawa
teaches away from having a capacitively coupled
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plasma in the wafer-to-ceiling gap of the process
chamber of Hanawa.

(Br. 8). Contrary to Appellants' argument, the portions of Hanawa relied
upon by Appellants are directed to inductive coupling and are silent
regarding capacitive coupling. In addition, Appellants have provided no
explanation as to how either of the portions of Hanawa referenced by
Appellants teaches away from or discourages having a capacitively coupled
plasma in the wafer-to-ceiling gap. Accordingly, Appellants' argument is
without persuasive merit.
Thus, it follows that Appellants have not identified reversible error in
the Examiner's finding that Hanawa does not teach away or in the
Examiner's determination that the plasma reactor having one or more RF
power generators supplying power to an electrode as required by claims 1
and 23 would have been obvious within the meaning of 35 U.S.C. § 103(a).

REJECTION (4)
With respect to rejection (4), Appellants' arguments focus on claim
35. Accordingly, we address Appellants' arguments regarding the rejection
with respect to claim 35 only. See 37 C.F.R. § 41.37(c)(1)(vii) (2009).
ISSUE
Did the Examiner err in determining that a plasma reactor having the
“one or more RF power generators capable of producing RF power at a . . .
frequency between about 60 to about 215 MHz coupled to the electrode” as
required by claim 35 would have been obvious over Hanawa in view of
Collins ‘420 within the meaning of 35 U.S.C. § 103(a) and that there is a
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reason to combine the teachings of Hanawa and Collins ‘420? We decide
these issues in the negative.

ADDITIONAL FINDINGS OF FACT (FF)
4. Appellants do not specifically dispute the Examiner's finding that
even though the abstract of Collins et al. '420 refers to
controlling the cathode sheath voltage and the ion
energy independent of the density with respect to the
wafer support, one of ordinary skill in the art would
have understood that such principles could equally be
applied to the top electrode since the top electrode is
being supplied with an independent RF power supply
from the RF power supply that controls the plasma
density.

(Compare Ans. 13 with Br. 12-14) (emphasis added). In addition,
Appellants do not specifically dispute the Examiner's reason for
combining Hanawa and Collins '420, which is to "couple the RF power
source to the electrode as taught by Collins et al. [to Hanawa’s
conductive showerhead] because the ion energy can be controlled
independently of the plasma density and process control can be
improved." (Compare Ans. 10 with Br. 12-14).
5. Appellants do not specifically dispute the Examiner's determination
that a prima facie case of obviousness exists because "the claimed
ranges 'overlap or lie inside ranges disclosed by the prior art.'"
(Compare Ans. 13-14 with Br. 12-14). Collins '420 teaches that its
Top or Antenna source may operate within the range of 100 KHz to
100 MHz to provide a dense plasma and its Bottom or Bias Source
may operate within the range of 100 KHz to about 100 MHz to
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control, inter alia, the cathode sheath voltage and ion energy. (Collins
'420, col. 11, ll. 25-67).

ANALYSES AND CONCLUSIONS
Appellants argue that "Collins ['420] fails to teach, suggest, or
otherwise lead to the motivation relied upon by the Examiner for the
modification of Hanawa." (Br. 12). Specifically, Appellants argue that
"Collins ['420] does not teach or suggest that RF power may be coupled to
an upper electrode 17S to provide the benefit relied upon by the Examiner."
(Br. 13).
In reference to our above discussion, Appellants do not specifically
dispute the Examiner's finding that one of ordinary skill would have
understood that Collins '420's teaching of an RF power supply for
controlling the cathode sheath voltage with respect to a wafer support could
also be applied to a top electrode (FF 4).
In addition, Appellants do not specifically dispute the Examiner's
reason for combining Hanawa and Collins '420, which is to "couple the RF
power source to the electrode as taught by Collins et al. [to Hanawa’s
conductive showerhead] because the ion energy can be controlled
independently of the plasma density and process control can be improved."
(FF 4). Because Appellants do not specifically dispute the Examiner's
factual findings or the Examiner's reason for combining Hanawa and Collins
'420, Appellants' argument is unpersuasive of reversible error.
Appellants also argue that "Collins fails to teach or suggest one or
more RF power generators capable of producing RF power at a second
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frequency of between about 60 to about 215 MHz coupled to the electrode,
as recited in claim 35." (Br. 13).
Appellants, however, do not specifically dispute the Examiner's
determination that a prima facie case of obviousness exists because "the
claimed ranges 'overlap or lie inside ranges disclosed by the prior art.'" (FF
5).
Thus, because Appellants do not specifically dispute the Examiner's
specific factual finding (FF 5) regarding Collins ‘420 or the Examiner's
reason for arriving at the claimed invention, we find Appellants' argument
unpersuasive of reversible error.
It follows that the Examiner did not err in determining that a plasma
reactor having the “one or more RF power generators capable of producing
RF power at a . . . frequency between about 60 to about 215 MHz coupled to
the electrode” feature as required by claim 35 would have been obvious over
Hanawa in view of Collins ‘420 within the meaning of 35 U.S.C. § 103(a).

ORDER
In summary, we affirm the Examiner's decision to reject the claims
stated in rejections (1) through (4).
Accordingly, the Examiner's decision is affirmed.

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TIME PERIOD
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(2009).

AFFIRMED

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