Ex Parte Rhodes et al

Board of Patent Appeals and Interferences

Aug 27, 2012

11213278 (B.P.A.I. Aug. 27, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/213,278 08/26/2005 Howard E. Rhodes MI22-4173 9164
21567 7590 08/28/2012
Wells St. John P.S.
601 West First Avenue
Suite 1300
Spokane, WA 99201-3828
EXAMINER
TRINH, MICHAEL MANH
ART UNIT PAPER NUMBER
2822
MAIL DATE DELIVERY MODE
08/28/2012 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte HOWARD E. RHODES and LUAN TRAN
____________

Appeal 2009-012843
Application 11/213,278
Technology Center 2800
____________

Before JOSEPH F. RUGGIERO, MAHSHID D. SAADAT, and
ANDREW CALDWELL, Administrative Patent Judges.

RUGGIERO, Administrative Patent Judge.

DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134(a) from the Final Rejection
of claims 1-7, which are all of the pending claims. We have jurisdiction
under 35 U.S.C. § 6(b).
We affirm.
Rather than reiterate the arguments of Appellants and the Examiner,
we refer to the Appeal Brief (filed Oct. 1, 2007), the Answer (mailed Jan.
28, 2008), and the Reply Brief (filed Mar. 18, 2008). We have considered in
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this decision only those arguments Appellants actually raised in the Briefs.
Any other arguments which Appellants could have made but chose not to
make in the Briefs are deemed to be waived. See 37 C.F.R.
§ 41.37(c)(1)(iv).

Appellants’ Invention
Appellants’ invention relates to a semiconductor device which has a
localized thick region positioned below the contact hole. According to
Appellants, the localized thick region lessens the risk of etching the contact
hole through the contacting conductive layer. See generally Spec. 3:10-25.

Claim 1 is illustrative of the invention and reads as follows:

1. A process for making a semiconductor device having an improved
contact to a conductive layer comprising the steps of:

providing a first layer of material and etching an opening therein, said
opening including sidewalls;

forming a layer of a first conductive material directly on said first
layer of material and extending along the surfaces of said sidewalls and into
said opening to form a localized thick region;

forming an overlayer of material on said layer of said first conductive
material;

etching a contact hole in said overlayer in an overetch amount
extending into said localized thick region; and

substantially filling said contact hole in said overlayer with a second
conductive material which differs in composition from said first conductive
layer and which contacts said first conductive material.
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The Examiner’s Rejections
1

The Examiner’s Answer cites the following prior art references:
Watanabe US 5,317,193 May 31, 1994
Bergemont US 5,484,741 Jan. 16, 1996
(eff. filed Dec. 16, 1993)
Jost US 5,563,089 Oct. 8, 1996
(eff. filed Feb. 22, 1995)
Zamanian US 5,793,111 Aug. 11, 1998
(eff. filed May 31, 1994)
Katsumata US 4,782,030 Nov. 1, 1998

Toshiyuki JP 05-109905 Apr. 30, 1993

Claims 1-7 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Jost in view of Bergemont and Zamanian.
Claims 1-7 stand further rejected under 35 U.S.C. § 103(a) as being
unpatentable over Katsumata in view of Toshiyuki, Zamanian and
Watanabe.

ANALYSIS
I. The Jost/Bergemont/Zamanian Rejection
Claims 1, 4, and 5
Appellants’ arguments, with respect to the obviousness rejection of
independent claim 1 and its dependent claim 4, initially contend that
Bergemont and Zamanian do not overcome what the Examiner has identified
as the deficiency of Jost, i.e., a second conductive material of metal which is

1
The Examiner has withdrawn the obviousness-type double patenting
rejection of claims 1-7 (Ans. 3). .
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different in composition from the first polysilicon conductive material.
According to Appellants, Bergemont does not teach that the respective first
and second conductive layers 122 and 126 have different compositions since
they both have a tungsten metal component (App. Br. 6; Reply Br. 2).
We do not agree with Appellants. Although Bergemont’s layers 122
and 126 may have a common tungsten metal component, we fail to see why
the disclosed titanium tungsten or titanium nitride composition of layer 122
would not be considered as different in composition than the plug layer 126
made solely of tungsten. Further, while Appellants (Reply Br. 2) contend
that Bergemont (col. 9, ll. 28-30) contemplates embodiments in which layers
122 and 126 would have the same composition, such is not precluded by the
language of claims 1 and 4.
We are also not persuaded by Appellants’ arguments challenging the
Examiner’s stated rationale for the proposed Jost/Bergemont/Zamanian
combination. According to Appellants (App. Br. 6; Reply Br. 3), the
Examiner erred in determining that the use of tungsten metal conductive
materials as taught by Bergemont and Zamanian for the second conductive
layer bit line 46 of Jost would improve the operation speed since tungsten
has a higher electrical conductivity than the polysilicon first conductive
layer. Appellants’ argument in support of this contention, i.e., that
Zamanian discloses aluminum, not tungsten, for the second conductive
material is incorrect since Zamanian indeed discloses (col. 5, l. 26) that
tungsten can be used as a bit line contact metal as pointed out by the
Examiner (Ans. 10).
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Lastly, we are not persuaded by Appellants’ argument (App. Br. 6-7;
Reply Br. 3-4), that the combined references, and Jost in particular, do not
disclose the etching of a contact hole in an overetch amount which extends
into a localized thick region of the first conductive layer as claimed. The
Examiner has taken the position that Jost discloses the overetch feature since
the vertical component of conductive layer 36, which the Examiner likens to
the claimed localized thick region, is etched down and recessed below the
top surface of layer 28 (Ans. 4 and 10-12).
According to Appellants (App. Br. 6-7; Reply Br. 3-4), the Examiner
erred because Jost does not teach a localized thick region as claimed since
there are no spacers along the sidewalls of Jost’s layer 28. As pointed out by
the Examiner (Ans. 11), however, there are no “spacers” recited in claims 1
and 4.
For the above reasons, the Examiner’s 35 U.S.C. § 103(a) rejection of
claims 1 and 4, as well as dependent claim 5 not separately argued by
Appellants, is sustained.

Claims 2, 3, 6, and 7
We also sustain the Examiner’s obviousness rejection of claims 2, 3,
6, and 7 which, unlike previously discussed claims 1, 4, and 5, include a
specific recitation of a localized thick region formed by a first conductive
material that forms “spacers” along the sidewalls of the etched opening of a
first layer of a material. We are not persuaded by Appellants’ argument that
the only “spacers” disclosed by Jost are elements 18 and 51 which are not
formed from conductive material as claimed.
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We find no error in the Examiner’s determination (Ans. 12-14) that
the vertical component of Jost’s conductive layer (36, Figs. 10-11) is formed
as a “spacer” along the sidewalls of the opening in layer 28. This is in
accord with Appellants’ description of localized thick region 34 at page 8,
lines 4-9 of the Specification and illustrated in Figure 8 of Appellants’
drawings. As previously discussed, we agree with the Examiner that this
vertical component is etched down and below the top surface of layer 28 in
correspondence with the claimed overetch feature.

II. The Katsumata/Toshiyuki/Zamanian/Watanabe Rejection
Claims 1, 4, and 5
We are not persuaded by Appellants initial contention that
Katsumata’s respective first and second conductive layers 25 and 32 do not
differ in composition as claimed since they both have a silicon component
(App. Br. 9). We agree with the Examiner (Ans. 15) that an ordinarily
skilled artisan would recognize that Katsumata’s first conductive layer 25,
made of polysilicon, differs in composition from the metal second
conductive layer 32 made of an aluminum-silicon alloy or aluminum-silicon-
copper alloy (col. 9, ll. 55-68; col. 10, ll. 3-20).
We also find unpersuasive Appellants’ argument that Katsumata does
not disclose a first conductive material that forms a localized thick region
(App. Br. 9). We find no error in the Examiner’s determination (Ans. 15-16)
that the vertically extending portion of Katsumata’s conductive layer (25 or
79), which fills the etched opening (Figs. 4J or 9M), has a vertical thick
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portion in accordance with Appellants’ description of the vertical portion 34
of conductive layer 26 illustrated in Figure 8 of Appellants’ drawings.
We further find unconvincing Appellants’ contention (App. Br. 9;
Reply Br. 4) that Katsumata does not teach etching into the localized thick
region of the first conductive material since the Examiner has relied upon
each of the secondary references Toshiyuki, Zamanian, and Watanabe, not
Katsumata, for this feature. We also find no error in the Examiner’s analysis
which explains how each of the secondary references discloses the
overetching of the top surface of a first conductive layer below the contact
opening of an overlayer material (Ans. 6, 7, and 17).
Further, contrary to Appellants’ contentions (App. Br. 10; Reply Br.
4-5), we find that the Examiner (Ans. 7) has provided an articulated line of
reasoning with a rational underpinning to support the conclusion of
obviousness. We agree with the Examiner’s determination (Ans. 18, 19)
that an ordinarily skilled artisan would have found that overetching the top
portion of the underlying conductive layer during contact hole etching, as
taught by each of Toshiyuki, Zamanian, and Watanabe, would have served
as an obvious enhancement in the fabrication of the device of Katsumata,
thereby providing, inter alia, improved multilayer interconnection reliability
and complete removal of overlayer dielectric from the contact hole. KSR
Int’l Co. v. Teleflex, Inc., 550 U.S. 398, 418 (2007).
For the above reasons, the Examiner’s 35 U.S.C. § 103(a) rejection of
claims 1 and 4, as well as dependent claim 5 not separately argued by
Appellants, is sustained.

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Claims 2, 3, 6, and 7
We also sustain the Examiner’s obviousness rejection of claims 2, 3,
6, and 7 which include a specific recitation of a localized thick region
formed by a first conductive material that forms “spacers” along the
sidewalls of the etched opening of a first layer of a material. As with our
previous discussion of Jost, we find no error in the Examiner’s
determination (Ans. 5, 6, 19, and 20) that the vertical component of
Katsumata’s conductive layer 25 is formed as a “spacer” along the sidewalls
of the etched out opening in the underlayer. As also previously discussed,
this is in accord with Appellants’ description of localized thick region 34 at
page 8, lines 4-9 of the Specification and illustrated in Figure 8 of
Appellants’ drawings.

CONCLUSION OF LAW
Based on the analysis above, we conclude that the Examiner did not
err in rejecting claims 1-7 for obviousness under 35 U.S.C. § 103(a).

DECISION
We affirm the Examiner’s decision rejecting claims 1-7 under
35 U.S.C. § 103(a).

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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)(2010).

AFFIRMED

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