Ex Parte Liu et al

Board of Patent Appeals and Interferences

Jun 9, 2009

11223780 (B.P.A.I. Jun. 9, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte SHENJIAN LIU
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Appeal 2009-001916
Application 11/223,780
Technology Center 1700
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Decided:1 June 10, 2009
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Before, CHARLES F. WARREN, BEVERLY A. FRANKLIN, and
LINDA M. GAUDETTE, Administrative Patent Judges.

FRANKLIN, Administrative Patent Judge.

DECISION ON APPEAL
STATEMENT OF THE CASE
Appellant seeks our review under 35 U.S.C. § 134 of the final

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, begins to run from the Decided Date
shown on this page of the decision. The time period does not run from the
Mail Date (paper delivery) or Notification Date (electronic delivery).
Appeal 2009-001916
Application 11/223,780

rejection of claims 1-14 and 16-19. We have jurisdiction under 35 U.S.C.
§ 6(b) (2002).
Claims 1 and 16 are representative of the subject matter on appeal and
are set forth below:
1. A method for selectively etching a high k layer with
respect to a silicon based material, comprising:

placing the high k layer into an etch chamber;

providing an etchant gas into the etch chamber, wherein the etchant
gas comprises H2 and BCl3; and

generating a plasma from the etchant gas to selectively etch the high k
layer with respect to the silicon based material.

16. A method for etching a stack with a high k layer over a
silicon based layer, comprising:

placing the stack into an etch chamber;

selectively etching the high k layer with respect to the silicon based
layer, comprising:

providing a high k layer etchant gas into the etch chamber, wherein
the high k layer etchant gas comprises H2 and BCl3; and

generating a plasma from the high k layer etchant gas to selectively
etch the high k layer with respect to the silicon based layer;

stopping the selectively etching the high k layer; and

selectively etching the silicon based layer with respect to the high k
layer.

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The prior art relied upon by the Examiner in rejecting the claims on
appeal is:
Donnelly, Jr. 6,511,872 B1 Jan. 28, 2003
Demmin 6,635,185 B2 Oct. 21, 2003
Hsu 2004/0140504 A1 Jul. 22, 2004
Chen 2005/0118353 A1 Jun. 02, 2005

SUMMARY OF THE DECISION
We affirm.
THE REJECTIONS
Claims 1-14 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Chen in view of Donnelly as evidenced by Demmin.
Claims 16-19 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Hsu in view of Chen and Donnelly as evidenced by
Demmin.
ISSUES
Has Appellant shown that the Examiner reversibly erred in concluding
that the claimed subject matter of providing an etchant gas comprising H2,
BCl3, and Cl2 for selectivity etching a high k layer is obvious in view of the
applied art? If not, has Appellant provided convincing evidence to rebut the
prima facie case of obviousness?

PRINCIPLES OF LAW
It is prima facie obvious to combine two compositions each
of which is taught by the prior art to be useful for the same
purpose, in order to form a third composition which is to be
used for the very same purpose. . . . [T]he idea of combining
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them flows logically from their having been individually
taught in the prior art.

In re Kerkhoven, 626 F.2d 846, 850 (CCPA 1980). See also In re Crockett,
279 F.2d 274, 276 (CCPA 1960); Ex parte Quadranti, 25 USPQ2d 1071
(BPAI 1992).
A particular parameter must first be recognized as a result-effective
variable, i.e., a variable which achieves a recognized result, before the
determination of the optimum or workable ranges of said variable might be
characterized as routine experimentation. In re Peterson, 315 F.3d 1325,
1330 (Fed. Cir. 2003) (“The normal desire of scientists or artisans to
improve upon what is already generally known provides the motivation to
determine where in a disclosed set of percentage ranges is the optimum
combination of percentages.”).
If a prima facie case of obviousness is established, the burden shifts to
the applicant to come forward with arguments and/or evidence to rebut the
prima facie case. See, e.g., In re Dillon, 919 F.2d 688, 692-693 (Fed. Cir.
1990). Rebuttal evidence and arguments can be presented in the
specification, In re Soni, 54 F.3d 746, 750 (Fed. Cir. 1995), by counsel, In re
Chu, 66 F.3d 292, 299 (Fed. Cir. 1995), or by way of an affidavit or
declaration under 37 C.F.R. § 1.132, e.g., Soni, 54 F.3d at 750; In re
Piasecki, 745 F.2d 1468, 1474 (Fed. Cir. 1984). However, arguments of
counsel cannot take the place of factually supported objective evidence. See,
e.g., In re Huang, 100 F.3d 135, 139-40, (Fed. Cir. 1996); In re De Blauwe,
736 F.2d 699, 705 (Fed. Cir. 1984).
When considering whether proffered evidence demonstrates
patentability, a side-by-side comparison of the claimed invention with the
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closest prior art which is commensurate in scope with the claims is needed,
with an explanation as to why the results would have been unexpected by
one of ordinary skill in the art. See In re Baxter Travenol Labs., 952 F.2d
388, 392 (Fed. Cir. 1991); In re De Blauwe, 736 F.2d at 705; In re Grasselli,
713 F.2d 731, 743 (Fed. Cir. 1983); In re Clemens, 622 F.2d 1029, 1035
(CCPA 1980); In re Freeman, 474 F.2d 1318, 1324 (CCPA 1973); In re
Klosak, 455 F.2d 1077, 1080 (CCPA 1972).

FINDINGS OF FACTS
Chen teaches a method of etching of a high-k layer in an etch chamber
comprising use of a halogen containing gas such as Cl2 as an etching gas.
Additionally, the process gas can include a reduction gas such as H2. Chen,
para. [0051]. A plasma may be generated from the etchant gas to selectively
etch the high k layer with respect to the silicon based material. Chen, paras.
[0043], [0045]-[0047], and Fig. 9. Chen teaches use of an inert gas also.
Chen, [0043], or [0047], last line; Ans. 3.
Donnelly teaches that a high-k material on a substrate may be
satisfactorily etched using halogen-containing gas[es] such as chlorine or
BCl3, and combinations thereof, the optimal mixtures of which can be
experimentally determined. Donnelly, col. 4, l. 67, to col. 5, l. 6; col. 1, ll.
64-66. Ans. 3.
With regard to variables such as volumetric flow ratio of processing
gases (see, .e.g., claims 6, 7, 11, 18 and 19), the Examiner finds that
Demmin evidences that such variables are result effect variables. Demmin,
col. 4, l. 64 through col. 5, l. 6 and col. 7, ll. 5-25. Ans. 5.
A discussion of Hsu is not necessary to our decision.
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ANALYSIS
1. Claims 1-14 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Chen in view of Donnelly as evidenced by
Demmin.
Chen teaches a method of etching a high-k layer in an etch chamber
comprising use of a halogen containing gas such as Cl2 as an etchant gas.
Additionally, the process gas can include a reduction gas such as H2. Chen,
para. [0051]. A plasma may be generated from the etchant gas to selectively
etch the high k layer with respect to the silicon based material. Chen, paras.
[0043], [0045]-[0047], and Fig. 9. Chen teaches use of an inert gas also.
Chen, [0043], or [0047], last line; Ans. 3.
The Examiner states that Chen is silent about using an etchant gas
comprising BCl3. The Examiner states that chlorine and BCl3 are the most
commonly used halogen-containing gases in the art of dry etching. The
Examiner finds that in a method of fabricating a semiconductor device,
Donnelly teaches that a high-k material on a substrate may be satisfactorily
etched using halogen-containing gas[es] such as chlorine or BCl3 and
combinations thereof. Donnelly, col. 5, ll. 1-3; col. 1, ll. 64-66. Ans. 3.
The Examiner concludes that it would have been obvious to one
having ordinary skill in the art to have included BCl3 in the etching process
of Chen because 1) Donnelly teaches that a high-k material on a substrate
may be satisfactorily etched using chlorine or BCl3, or combinations thereof,
and 2) Chen includes the use of a halogen containing gas such as Cl2 for the
same purpose, with hydrogen as a reduction gas. Ans. 3-4.
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The Examiner further states because the applied art teaches that the
same materials are used in the same etching process, it would have been
expected that the method of the combined prior art would contain the same
properties and functions as claimed (e.g., selectively etch the high k layer
with respect to the silicon based material). Id.
With regard to variables such as volumetric flow ratio of processing
gases (see, .e.g., claims 6, 7, 11, 18 and 19), the Examiner’s position is that
these are result-effective variables. Ans. 4-5. In support thereof, the
Examiner refers to col. 4, l. 64 through col. 5, l. 6 and col. 7, ll. 5-25 of
Demmin. Ans. 5. Absent objective evidence to the contrary, we agree.2 In
re Peterson, 315 F.3d at 1330.
With regard to claim 14, the Examiner states that claim 14 differs
from the prior art by specifying a conventional process (such as etching the
silicon based material layer subsequent to selectively etching the high-k
layer) in the art of semiconductor device fabrication, and the Examiner takes
official notice of such. The Examiner concludes that a person having
ordinary skill in the art would have found it obvious to have modified the
prior art by adding conventional process steps in order to complete the
semiconductor device fabrication with a reasonable expectation of success.
The Examiner points out that Appellant did not traverse this official notice
taken (which has been stated in the Office Action of December 29, 2006).

2 In response to this position taken by the Examiner, on page 7 of the Brief,
Appellant refers to a Declaration submitted on August 22, 2007 in an effort
to show that such parameters are not the result of routine experimentation.
This Declaration is discussed infra.

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Ans. 5. We therefore agree with the Examiner’s position regarding claim
14.
Appellant argues that Chen discloses etching a high-k dielectric
material using an etchant gas that includes H2, but does not disclose an
etchant gas that also includes BC13. Appellant argues that Donnelly
discloses etching a high-k dielectric material using an etchant gas that
includes BC13, but does not disclose an etchant gas that also includes H2.
Appellant asserts that therefore, individually, neither Chen nor Donnelly
discloses an etchant gas that includes both H2 and BC13.
We are not convinced by the aforementioned argument. One cannot
show nonobviousness by attacking references individually where the
rejections are based on combinations of references. In re Keller, 642 F.2d
413, 425-426 (CCPA 1981); In re Merck & Co., Inc., 800 F.2d 1091, 1097-
1098 (Fed. Cir. 1986). In the instant case, the Examiner’s analysis is
correct:
It is prima facie obvious to combine two compositions each
of which is taught by the prior art to be useful for the same
purpose, in order to form a third composition which is to be
used for the very same purpose. . . . [T]he idea of combining
them flows logically from their having been individually
taught in the prior art.

Kerkhoven, 626 F.2d at 850; Crockett, 279 F.2d at 276; Quadranti,
25 USPQ2d 1071. Chen teaches to etch a high-k dielectric layer using Cl2,
along with a reduction gas of H2. Chen, [0051]. Donnelly teaches that BCl3
is an etchant gas for a high-k dielectric layer. Donnelly teaches that BCl3
can be used in combination with Cl2, as etchants, for etching a high-k
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dielectric layer. Hence, the applied art teaches that each of Cl2 and BCl3 are
useful for the same purpose. “[T]he idea of combining them flows logically
from their having been individually taught in the prior art.” Id. Therefore,
including BCl3 in the process of Chen would have been obvious. Id.
Because Chen teaches both Cl2 and H2 in the process gas, the applied art as a
whole makes obvious use of H2 in combination with BC13 or Cl2 or both.3
Appellant argues that gases in etch processes have strong interactions.
For example, although two gases, gas A and gas B, work individually for
certain cases, mixing gas A and gas B may not work at all. By analogy,
Appellant argues that the etchant gas disclosed in Chen, which includes H2,
and the etchant gas disclosed in Donnelly, which includes BC13, may work
for the specific applications discussed in Chen and Donnelly respectively.
Appellant argues that mixing the two gases does not necessarily result in an
etchant gas that works well or works at all for selectively etching high-k
dielectric material. Br. 6.
In support thereof, Appellant refers to a Declaration submitted by one
of the inventors, Shenjian Liu, under 37 C.F.R. § 1.132 on August 22, 2007.
Therein, the inventors conducted multiple experiments in order to determine
the suitable etchant gas combination and ratios, including experiments using
alternative gas combinations. Appellant states that the Declaration shows
that only after several weeks of experiments, were the inventors able to

3 On pages 10-12 of the Brief, Appellant discusses the ruling of KSR
International Co., v. Teleflex Inc., 550 U.S. 398 (2007). We are not
convinced by Appellant’s statements therein, because, as discussed, supra,
the Examiner’s analysis in making his rejection supports a prima facie case
of obviousness.
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determine the desirable gas combination and ratios. The inventors learned
from their experimental data that H2, BC13, and C12 each performs a specific
function during the etch process. For example, BC13 is the main etchant
gas. C12 helps lessen the amount of deposition during the etch process. H2
helps break the bonds of high K and suppress silicon etch rate. Appellant
points out that the declarant inventor, who is a person of the ordinary skill in
the art, declares that it would not have been obvious to the inventor to
combine Chen and Donnelly to obtain an etchant gas that includes both H2
and BC13. Br. 6.
The above declaration evidence is not convincing. As pointed out by
the Examiner on page 10 of the Answer, the Declaration does not show
results that are unexpected. When considering whether proffered evidence
demonstrates patentability, a side-by-side comparison of the claimed
invention with the closest prior art which is commensurate in scope with the
claims is needed, with an explanation as to why the results would have been
unexpected by one of ordinary skill in the art. See In re Baxter Travenol
Labs., 952 F.2d at 392; In re De Blauwe, 736 F.2d at 705; In re Grasselli,
713 F.2d at 743; In re Clemens, 622 F.2d at 1035; In re Freeman, 474 F.2d
at 1324; In re Klosak, 455 F.2d at 1080. Appellant’s submitted Declaration
does not provide such evidence.
In view of the above, we affirm the rejection of claims 1-14 under 35
U.S.C. § 103(a) as being unpatentable over Chen in view of Donnelly as
evidenced by Demmin.
2. Claims 16-19 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Hsu in view of Chen and Donnelly as evidenced by
Demmin.
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On pages 8-9 of the Brief, Appellant essentially presents the same
arguments for this rejection as presented for the previous rejection.
Appellant again refers to the Declaration submitted on August 22, 2007, and
argues that variables such a volumetric flow ratios are not determined by
“routine experiment” as stated by the Examiner.
For the reasons set forth in response to the previous rejection, supra,
we are not convinced by Appellant’s arguments or Declaration.
In view of the above, we affirm the rejection of claims 16-19 under 35
U.S.C. § 103(a) as being unpatentable over Hsu in view of Chen and
Donnelly as evidenced by Demmin.
CONCLUSIONS OF LAW
Appellant has not shown that the Examiner reversibly erred in
concluding that the claimed subject matter of providing an etchant gas
comprising H2, BCl3, and Cl2 for selectivity etching a high k layer is obvious
in view of the applied art. Appellant has not provided convincing evidence
to rebut the prima facie case of obviousness.

DECISION
Each of the rejections is affirmed.

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)(iv).

AFFIRMED

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