Ex Parte Lee et al

Board of Patent Appeals and Interferences

Jan 29, 2009

11524656 (B.P.A.I. Jan. 29, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte JONG JAN LEE,
JER-SHEN MAA,
DOUGLAS J. TWEET,
and SHENG TENG HSU
____________

Appeal 2008-5382
Application 11/524,656
Technology Center 2800
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Decided: January 29, 2009
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Before CHARLES F. WARREN, CATHERINE Q. TIMM, and
MICHAEL P. COLAIANNI, Administrative Patent Judges.

TIMM, Administrative Patent Judge.

DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134(a) from the Examiner’s
decision rejecting claims 1-10, 12, 13, 15, 21-30, and 32-34. We have
jurisdiction under 35 U.S.C. § 6(b).
Appeal 2008-5382
Application 11/524,656

We AFFIRM.
STATEMENT OF THE CASE
The invention relates to a photodetector for the absorption of infrared
(IR) wavelength light which includes a silicon-germanium (SiGe) optical
path structure normal to a silicon (Si) substrate surface and having an optical
path length perpendicular to the substrate surface. (Spec. 3, ll. 12-14). The
invention is also directed to the process for preparing a SiGe optical path
structure. (Spec. 1, ll. 11-13). Claims 21 and 34 are illustrative of the
subject matter on appeal:
21. A silicon-germanium (SiGe) optical path with a path length
normal to a silicon (Si) substrate surface, for infrared (IR) photodetection,
the structure comprising:

a Si substrate with a surface;

a Si feature, normal with respect to the Si substrate surface; and,

a SiGe optical path overlying the Si feature, having an optical path
length perpendicular to the substrate surface.

34. An infrared (IR) photodetector comprising:
a CMOS active region formed in a silicon (Si) substrate with a
surface, the active region selected from a group consisting of a transistor
source, drain, gate, and a diode region;

an interconnect in electrical communication with the active region;

a Si feature, normal with respect to the Si substrate surface, and in
electrical communication with the interconnect; and

a SiGe optical path overlying the Si feature having an optical path
length perpendicular to the substrate surface.

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The Examiner relies on the following prior art references to show
unpatentability:
Sugiyama US 6,307,242 B1 Oct. 23, 2001
Chu et al. US 2002/0171077 A1 Nov. 21, 2002
The Examiner maintains the following rejections:
1. Claims 1-5, 8-10, 12, 13, 21-25, 28-30, 32, and 33 rejected under
35 U.S.C. § 102(b) as anticipated by Sugiyama;
2. Claims 6, 7, 26, and 27 rejected under 35 U.S.C. § 103(a) as
obvious over Sugiyama; and
3. Claims 15 and 34 rejected under 35 U.S.C. § 103(a) as obvious
over Sugiyama in view of Chu et al. (“Chu”).
With respect to the first rejection under 35 U.S.C. § 102(b), no claims
are argued separately from the others.1 (App. Br. 8-10). With respect to the
rejections of dependent claims 6, 7, 26, and 27 under 35 U.S.C. § 103(a), no
sufficiently distinct argument is made with respect to those made for the
rejection of independent claims 1 and 21, from which the claims depend.
(App. Br. 10-11). With respect to the rejection of claims 15 and 34 under
35 U.S.C. § 103(a), claims 15 and 34 are not argued separately. (App. Br.
11-13). Thus, we decide this Appeal on the basis of representative
independent claims 21 and 34, both of which are apparatus claims. See
37 C.F.R. § 41.37(c)(1)(vii) (“When multiple claims subject to the same
ground of rejection are argued as a group by appellant, the Board may select
a single claim from the group of claims that are argued together to decide the

1 In particular, we note that method claims 1 and 15 are not argued
separately from apparatus claim 21.
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appeal with respect to the group of claims as to the ground of rejection on
the basis of the selected claim alone.”).
I. ANTICIPATION
A. ISSUES ON APPEAL
Appellants contend that Sugiyama teaches a device having an optical
path length that is parallel to the Si substrate surface, not perpendicular to
the Si substrate surface, as required by claim 21. (App. Br. 8-9). The
Examiner contends that the waveguide taught by Sugiyama includes two
optical paths, either perpendicular or parallel to the Si substrate surface
depending upon how the light is incident to the waveguide, and that the
selection of an optical path is no more than a selection of the intended use of
the claimed structure. (Ans. 10-11).
A first issue on appeal arising from the contentions of Appellants and
the Examiner is: does Sugiyama teach a device having an optical path length
in a direction perpendicular to the Si substrate surface? We answer this
question in the affirmative.
B. FACTUAL FINDINGS
The following Findings of Fact (FF) are directed to the above
identified issues on appeal:
1. Claim 21 is directed to a Si structure. (See Claim 21).
2. Sugiyama teaches light incident into the Si waveguide via the
core 6 of an optical fiber in an orientation as disclosed in Figure 1.
(Sugiyama, col. 4, l. 36-41; Figure 1).
3. As such, the incident light moves in a path that is parallel to the
Si substrate, as demonstrated by the arrow in Figure 2A. (Sugiyama, col. 4,
ll. 49-52; Figure 2A).
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4. Appellants state that “[i]t is well known in the art to define an
optical path length as the direction in which light travels.” (App. Br. 9).
5. Appellants also state that “an expert in the art would understand
the orientation of an optical path, once the length is defined.” (App. Br. 10).
6. Sugiyama teaches that reflective layers 210 are deposited on
parallel surfaces S1 and S2 above and below the waveguide. (Sugiyama,
col. 4, ll. 52-55; Figure 2B).
7. The reflective layers 210 are oxidized silicon film, or SiO2.
(Sugiyama, col. 5, l. 3).
8. In Figures 3 and 6, these reflective layers are labeled 14 and 10.
(Sugiyama, col. 5, ll. 24-25; Figures 3 and 6).
9. Appellants’ Specification also discloses that light can be
incident in a direction perpendicular to the Si substrate, despite the presence
of an interlayer dielectric (ILD) of SiO2 overlying the SiGe optical path.
(Spec. 9, ll. 14-17; 11, ll. 5-7; 14, ll. 1-3 and 15-16; Figures 5, 11, 12, 13, 17,
and 18).
10. Appellants’ Specification teaches that a microlens can be used
to focus the incident light into the SiGe optical path through the SiO2 ILD.
(Spec. 9, ll. 14-17; 11, ll. 8-9 and 14-16; 14, ll. 3-4 and 16-18; Figures 5, 12,
13, 17, and 18).
C. PRINCIPLES OF LAW
“To anticipate a claim, a prior art reference must disclose every
limitation of the claimed invention, either explicitly or inherently.” In re
Schreiber, 128 F.3d 1473, 1477 (Fed. Cir. 1997). If the prior art structure
possesses all the claimed characteristics including the capability of
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performing the claimed function, then there is a prima facie case of
unpatentability. In re Ludtke, 441 F.2d 660, 663-64 (CCPA 1971).
When a claimed product appears to be substantially identical to a
product disclosed by the prior art, the burden is on the Applicants to prove
that the product of the prior art does not necessarily or inherently possess
characteristics or properties attributed to the claimed product. In re Spada,
911 F.2d 705, 708 (Fed. Cir. 1990).
Appellants’ attorney arguments do not take the place of evidence in
the record. In re Pearson, 494 F.2d 1399, 1405 (CCPA 1974).
D. ANALYSIS
Appellants do not contest the Examiner’s finding that Sugiyama
teaches a Si substrate and a Si feature normal to the Si substrate and a SiGe
optical path overlying the Si feature. (See generally App. Br.). While
Sugiyama illustrates light incident to the structure in a direction parallel to
the Si substrate, for example via the core of an optical fiber 6 (FF 2 and 3),
we find that the light may be incident in a direction perpendicular to Si
substrate without changing the structure taught by Sugiyama. For example,
the optical fiber need only be moved such that the light from the core 6 was
incident in a perpendicular direction. The structure would not change in any
way, but the optical light path would be in a perpendicular, rather than
parallel direction. Thus, the structure taught by Sugiyama would be capable
of having an optical path length perpendicular to the substrate surface, since
it is a characteristic of the material and structure of the claimed Si structure.
Ludtke, 441 F.2d at 663-64. Appellants’ own arguments suggest that the
optical path length can be “defined” without indicating any changes need to
be made to the structure. (FF 4 and 5). Thus, Sugiyama teaches a device
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having an optical path length in a direction perpendicular to the Si substrate
surface when IR light is incident in a perpendicular rather than parallel
direction. We agree with the Examiner that the structure taught by
Sugiyama reasonably appears to be identical to the structure claimed, and
thus the burden falls to the Appellant to prove that, in fact, a patentable
structural difference arises due to the fact that Sugiyama teaches propagating
light in a direction parallel, rather than perpendicular to, the Si substrate.
Spada, 911 F.2d at 708.
In the Reply Brief, Appellants argue that “Sugiyama discloses a
waveguide with a single optical path” because reflective layers 210 (S1 and
S2) would “necessary [sic, necessarily] prevent light from entering the
waveguide in the perpendicular direction” such that “light cannot enter the
waveguide through top reflective layer 210.” (See Reply Br. 2-3).
However, Appellants provided only attorney argument, which is insufficient
evidence, that IR light cannot travel through reflective layers 210. Pearson,
494 F.2d at 1405. Further, such an argument contradicts the disclosure in
Appellants’ Specification. The reflective layers 210 taught by Sugiyama are
made from SiO2 (FF 6-8), which is the same material as the interlayer
dielectric (ILD) through which incident IR light travels in Appellants’
Specification. (FF 9). While Appellants’ Specification uses a microlens to
focus the light through the ILD and into the SiGe layers (FF 10), the addition
of a microlens is not excluded from the claimed invention or from the
teachings of Sugiyama. Thus, Appellants have not demonstrated that the
presence of a SiO2 layer precludes an optical path length perpendicular to
the Si substrate.
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Accordingly, we sustain the Examiner’s rejection under 35 U.S.C.
§ 102.
II. OBVIOUSNESS REJECTION OF CLAIMS 6, 7, 26, AND 27
The Examiner has rejected claims 6, 7, 26, and 27 under 35 U.S.C.
§ 103. However, Appellants make no arguments against the Examiner’s
prima facie case of obviousness over and above the arguments discussed
above with respect to independent claims 1 and 16, from which claims 6, 7,
26, and 27 depend. Accordingly, for the same reasons as discussed above,
we sustain the Examiner’s rejection of claims 6, 7, 26, and 27 under
35 U.S.C. § 103.
III. OBVIOUSNESS REJECTION OF CLAIM 34
A. ISSUES ON APPEAL
Appellants contend that the Examiner has not adequately explained
how an expert in the art could have modified Sugiyama or Chu to arrive at
the claimed invention. (App. Br. 12). The Examiner contends that it would
have been obvious to one of ordinary skill in the art to form a CMOS active
region as taught by Chu interconnected with the photodetector of Sugiyama
to obtain an entire subsystem monolithically on a chip. (Ans. 12).
A second issue on appeal arising from the contentions of Appellants
and the Examiner is: would it have been obvious to one of ordinary skill in
the art to interconnect a CMOS active region with the photodetectors of
Sugiyama based on the teachings of Chu?
B. FACTUAL FINDINGS
The following additional Findings of Fact are directed to the above
identified issues on appeal:
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11. Chu teaches a “monolithically integrating a high-speed
photodetector and a high mobility transistor . . . using a Si-manufacturing
process incorporating SiGe epitaxial layers.” (Chu, ¶ 18).
12. In particular, Chu teaches “monolithically integrating a high-
speed photodetector . . . with a manufacturable CMOS logic process,
enabling an entire optical/analog/digital subsystem to be fabricated
monolithically on a chip.” (Chu, ¶ 19).
13. Chu also teaches that “the embodiment in FIG. 13 can
potentially be used to fabricate a high-speed photoreciever circuit on the
same chip as a high-speed, low power CMOS technology, for future
‘system-on-a-chip’ applications.” (Chu, ¶ 52).
C. PRINCIPLES OF LAW
“Section 103 forbids issuance of a patent when ‘the differences
between the subject matter sought to be patented and the prior art are such
that the subject matter as a whole would have been obvious at the time the
invention was made to a person having ordinary skill in the art to which said
subject matter pertains.’” KSR Int’l Co. v. Teleflex Inc., 127 S. Ct. 1727,
1734 (2007). The question of obviousness is resolved on the basis of
underlying factual determinations including (1) the scope and content of the
prior art, (2) any differences between the claimed subject matter and the
prior art, (3) the level of skill in the art, and (4) where in evidence, so-called
secondary considerations. Graham v. John Deere Co., 383 U.S. 1, 17-18
(1966). See also KSR, 127 S. Ct. at 1734 (“While the sequence of these
questions might be reordered in any particular case, the [Graham] factors
continue to define the inquiry that controls.”).
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“A person of ordinary skill is also a person of ordinary creativity, not
an automaton.” KSR, 127 S. Ct. at 1742. The Supreme Court clarified that
“it can be important to identify a reason that would have prompted a person
of ordinary skill in the relevant field to combine the elements in the way the
claimed new invention does,” but that “the analysis need not seek out precise
teachings [in the prior art] directed to the specific subject matter of the
challenged claim.” Id. at 1741.
D. ANALYSIS
Applying the preceding legal principles to the Factual Findings in the
record of this appeal, we determine that the Examiner has established a
prima facie case of obviousness.
Chu clearly teaches that it was well known in the art to integrate
CMOS logic with a photodetector on the same chip. (FF 11-13). Although
the Examiner has not provided precise details as to how one of ordinary skill
in the art would modify Sugiyama with the teachings of Chu, we can
appreciate the inferences and creative steps that a person of ordinary skill in
the art would employ to do so. KSR, 127 S. Ct. at 1742. We find sufficient
reasoning provided by the Examiner as to why one of ordinary skill in the art
would modify the photodetector of Sugiyama to integrate CMOS logic as
taught by Chu. KSR, 127 S. Ct. at 1741. Therefore, it would have been
obvious to one of ordinary skill in the art to interconnect a CMOS active
region with the photodetectors of Sugiyama based on the teachings of Chu.
Appellants have not provided any rationale as to why it would not be within
the skill of one of ordinary skill in the art to make such a modification.
Accordingly, we sustain the Examiner’s rejection of claims 15 and 34
under 35 U.S.C. § 103.
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IV. CONCLUSION
In summary:
1. We sustain the Examiner’s rejection of claims 1-5, 8-10, 12, 13, 21-
25, 28-30, 32, and 33 under 35 U.S.C. § 102(b) as anticipated by Sugiyama;
2. We sustain the Examiner’s rejection of claims 6, 7, 26, and 27 under
35 U.S.C. § 103(a) as obvious over Sugiyama; and
3. We sustain the Examiner’s rejection of claims 15 and 34 under
35 U.S.C. § 103(a) as obvious over Sugiyama in view of Chu.
V. DECISION
We affirm the Examiner’s decision.
VI. TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal maybe extended under 37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED

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