SunPower Corporation

Patent Trials and Appeals Board

Oct 29, 2021

2021001815 (P.T.A.B. Oct. 29, 2021)

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.
16/154,416 10/08/2018 Douglas H. ROSE 10031.000430 2093
74254 7590 10/29/2021
Law Office of Patrick D. Benedicto
P.O. Box 641330
San Jose, CA 95164-1330
EXAMINER
TRAN, TONY
ART UNIT PAPER NUMBER
2894
MAIL DATE DELIVERY MODE
10/29/2021 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 PATENT TRIAL AND APPEAL BOARD
__________

Ex parte DOUGLAS H. ROSE,
PONGSTHORN URALWONG, and DAVID D. SMITH
__________

Appeal 2021-001815
Application 16/154,416
Technology Center 2800
___________

Before ADRIENE LEPIANE HANLON, N. WHITNEY WILSON, and
CHRISTOPHER C. KENNEDY, Administrative Patent Judges.

HANLON, Administrative Patent Judge.

DECISION ON APPEAL

A. STATEMENT OF THE CASE
The Appellant1 filed an appeal under 35 U.S.C. § 134(a) from an Examiner’s
decision finally rejecting claims 1–7 and 21–29. We have jurisdiction under
35 U.S.C. § 6(b).
We REVERSE.

1 “Appellant” refers to “applicant” as defined in 37 C.F.R. § 1.42. The Appellant
identifies the real party in interest as SunPower Corporation. Appeal Brief dated
October 21, 2020 (“Appeal Br.”), at 1.
Appeal 2021-001815
Application 16/154,416

2

Representative claim 1 is reproduced below from the Claims Appendix to
the Appeal Brief. The limitations at issue are italicized.
1. A backside-contact solar cell comprising:
a substrate;
a dielectric layer over the substrate, the dielectric layer being on
a backside of the backside-contact solar cell, the backside of the
backside-contact solar cell being opposite a front side of the backside-
contact solar cell, the front side of the backside-contact solar cell
being configured to face towards the sun;
a first copper layer over the dielectric layer on the backside of
the backside-contact solar cell, the first copper layer being electrically
coupled to a first doped region of the back-side contact solar cell;
a first tin layer on the first copper layer;
a second copper layer over the dielectric layer on the backside
of the backside-contact solar cell, the second copper layer being
electrically coupled to a second doped region of the back-side contact
solar cell; and
a second tin layer on the second copper layer.
Appeal Br. 8.
The Examiner maintains the following grounds of rejection on appeal:
(1) claims 1–3, 7, and 21–26 under 35 U.S.C. § 103(a) as unpatentable
over Katsu2 in view of Rinne;3
(2) claims 4, 5, 27, and 28 under 35 U.S.C. § 103(a) as unpatentable over
Katsu in view of Rinne, further in view of Mis;4 and
(3) claims 6 and 29 under 35 U.S.C. § 103(a) as unpatentable over Katsu
in view of Rinne and Mis, further in view of Leinkram.5

2 US 2001/0011553 A1, to Katsu, published August 9, 2001 (“Katsu”).
3 US 6,492,197 B1, to Rinne, issued December 10, 2002 (“Rinne”).
4 US 2005/0020047 A1, to Mis et al., published January 27, 2005 (“Mis”).
5 US 3,833,425, to Leinkram et al., issued September 3, 1974 (“Leinkram”).
Appeal 2021-001815
Application 16/154,416

3

B. DISCUSSION
According to claim 1, the first copper/tin structure and the second copper/tin
structure are both on the backside of a backside-contact solar cell. Appeal Br. 8;
see also Appeal Br. 4. To illustrate, the Appellant’s Figure 1 is reproduced below.

Appellant’s Figure 1 is a sectional view schematically
illustrating a solar cell according to an embodiment
of the Appellant’s invention.
According to the Appellant, dielectric layer 102 is over substrate 100. First
copper layer 110 is over dielectric layer 102, and first tin layer 112 is on first
copper layer 110. Similarly, second copper layer 110 is over dielectric layer 102,
and second tin layer 112 is on second copper layer 110. Appeal Br. 2. First copper
layer is said to be electrically coupled to a first doped region of the solar cell, and
second copper layer is said to be electrically coupled to a second doped region of
the solar cell. Appeal Br. 2.
The Examiner finds Katsu discloses a solar cell comprising substrate 1 and
dielectric layer 10 over the substrate. Final Act. 2.6 The Examiner finds that
contact layers 5, 6 of the solar cell are formed over dielectric layer 10 on the

6 Final Office Action dated September 22, 2020.
Appeal 2021-001815
Application 16/154,416

4

backside of the solar cell and are electrically coupled to first doped region 1. Final
Act. 2. Katsu Figure 1 is reproduced below.

Katsu Figure 1 is a cross-sectional view of a
solar cell according to Katsu’s invention.
The Examiner finds Katsu does not disclose a first copper layer over
dielectric layer 10, a first tin layer on the first copper layer, a second copper layer
over dielectric layer 10, and a second tin layer on the second copper layer as
claimed. Final Act. 3; see also Appeal Br. 4 (arguing that in Katsu, a contact
structure comprising electrodes 5/6 on the backside of the solar cell connects to a
first doped region (i.e., P-type silicon substrate 1) and a contact structure
comprising electrode 3 on the front side of the solar cell connects to a second
doped region (i.e., N-type diffusion layer 2)).
Rinne discloses a solder bump, not a backside-contact solar cell as claimed.
Nonetheless, the Examiner finds Rinne discloses first and second copper layers and
first and second tin layers as claimed. More specifically, the Examiner finds Rinne
discloses first copper layer 130b over dielectric layer 120, first tin layer 150 on
first copper layer 130b, second copper layer 130c over dielectric layer 120, and
second tin layer 160 on second copper layer 130c. Final Act. 3. Rinne Figure 2 is
reproduced below.
Appeal 2021-001815
Application 16/154,416

5

Rinne Figure 2 is a cross-sectional view of a
solder bump according to Rinne’s invention.
The Examiner concludes that it would have been obvious to one of ordinary
skill in the art
to include [Rinne’s] teaching for the purpose of enhancing the
connectivity between devices since it has been held to be within the
general skill of a worker in the art to select a known material on the
basis of its suitability for the intended use as a matter of obvious
design choice.
Final Act. 3.
The Examiner finds that the proposed combination of Katsu and Rinne
teaches
a first copper layer over the dielectric layer on the backside of the
backside-contact solar cell, the first copper layer being electrically
coupled to a first doped region of the back-side contact solar cell; a
first tin layer on the first copper layer; a second copper layer over the
dielectric layer on the backside of the backside- contact solar cell [as
claimed].
Final Act. 3 (original emphasis omitted).
The Appellant argues that “the proposed modification goes beyond mere
selection of materials, but instead requires major structural changes to Katsu’s
Appeal 2021-001815
Application 16/154,416

6

solar cell.” Appeal Br. 4–5. In that regard, the Appellant argues that “modifying
Katsu using Rinne’s materials would still result in contact structures to doped
regions on opposite sides of the solar cell.” Appeal Br. 5 (emphasis added).
The Appellant’s argument is persuasive of reversible error. Claim 1 recites
that first copper layer, first tin layer, second copper layer, and second tin layer are
on the same side (i.e., the backside) of the solar cell, and the first copper layer is
electrically coupled to a first doped region of the solar cell and the second copper
layer is electrically coupled to a second doped region of the solar cell.7 Appeal Br.
8; see also Reply Br. 48 (stating that “claim 1 recites that both the first copper layer
and the second copper layer are over the dielectric layer on the backside of the
backside-contact solar cell”).
In the obviousness rejection on appeal, we understand that the Examiner
relies on Rinne to modify the materials in Katsu’s solar cell. However, on this
record, it is unclear which layers in Katsu’s modified solar cell correspond to the
claimed first copper layer, first tin layer, second copper layer, and second tin layer.
In that regard, we note that electrode 5 in Katsu is a single layer over dielectric
layer 10, wherein dielectric layer 10 has openings 11 for establishing an electrical

7 Notably, claim 1 does not recite that the first and second doped regions of the
solar cell comprise different dopants or different amounts of the same dopant(s).
Independent claim 21, on the other hand, recites that a first copper layer is
electrically coupled to a p-doped region on the backside of the solar cell and a
second copper layer is electrically coupled to an n-doped region on the backside of
the solar cell. Appeal Br. 9. Claim 21 recites that the first and second copper
layers are over a dielectric layer, which is on a backside of the solar cell, and first
and second tin layers are on the first and second copper layers, respectively.
Appeal Br. 9; see also Appeal Br. 6 (stating that “in the embodiment of claim 21,
the contact structures to the P-type and N-type doped regions are both on the
backside of the solar cell”).
8 Reply Brief dated January 12, 2021.
Appeal 2021-001815
Application 16/154,416

7

connection between substrate 1 and electrodes 5 and 6. See Katsu ¶ 45; Katsu Fig.
2. Similarly, electrode 6 in Katsu is a single layer on electrode 5. Significantly,
the Examiner does not explain, in any detail, why one of ordinary skill in the art
would have provided two separate copper layers and two separate tin layers on the
same side (i.e., the backside) of Katsu’s solar cell based on the combined teachings
of Katsu and Rinne, wherein the first copper layer is electrically coupled to a first
doped region and the second copper layer is electrically coupled to a second doped
region as claimed.
For the reasons discussed above, the obviousness rejection of claims 1–3, 7,
and 21–26 based on the combination of Katsu and Rinne is not sustained. The
Examiner does not rely on Mis and/or Leinkram to cure the deficiency in the
combination of Katsu and Rinne identified above. Therefore, the obviousness
rejection of claims 4, 5, 27, and 28 based on the combination of Katsu, Rinne, and
Mis and the obviousness rejection of claims 6 and 29 based on the combination of
Katsu, Rinne, Mis, and Leinkram also are not sustained.
C. CONCLUSION
The Examiner’s decision is reversed.
In summary:

Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1–3, 7, 21–26 103(a) Katsu, Rinne 1–3, 7, 21–26
4, 5, 27, 28 103(a) Katsu, Rinne, Mis 4, 5, 27, 28
6, 29 103(a) Katsu, Rinne, Mis,
Leinkram
6, 29
Overall
Outcome
1–7, 21–29

REVERSED