Ex Parte Di Cioccio et al

Patent Trial and Appeal Board

Jul 29, 2014

10519406 (P.T.A.B. Jul. 29, 2014)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
__________

Ex parte LEA DI CIOCCIO,
FABRICE LETERTRE,
and ELSA HUGONNARD-BRUYERE
__________

Appeal 2012-006731
Application 10/519,406
Technology Center 2800
___________

Before ADRIENE LEPIANE HANLON, CATHERINE Q. TIMM, and
GEORGE C. BEST, Administrative Patent Judges.

HANLON, Administrative Patent Judge.

DECISION ON APPEAL
A. STATEMENT OF THE CASE
Lea Di Cioccio, et al. (“Appellants”) appeal under 35 U.S.C. § 134
from a final rejection of claims 10-13 and 18-21, which are all of the
pending claims. We have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM and designate the affirmance a new ground of rejection.
The subject matter on appeal is directed to a method for transferring
an electrically active SiC thin layer from an initial SiC substrate. In general,
the method comprises the steps of determining hydrogen ion implantation
conditions that create a buried, embrittled film having a particular
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implantation defect concentration, performing hydrogen ion implantation
through a face of the initial SiC substrate under these conditions to create the
buried, embrittled film, fastening the face of the initial SiC substrate after
implantation to a target substrate to obtain a structure, separating the
structure in two parts at a level of the buried embrittled film, and thinning a
layer of the SiC remaining fastened to the target substrate to a particular
thickness. App. Br. 13-14.1
In describing the “STATE OF THE PRIOR ART” in the
Specification, the Appellants disclose that, at the time of the Appellants’
invention, the following method was used to produce thin films of semi-
conductive material:
The thin film is first delimited in an initial substrate by ion
implantation. One face of the substrate is bombarded with ions
(generally hydrogen ions) according to a determined dosage and
energy in order to create a buried, embrittled film at a depth, in
relation to the bombarded face, close to the average penetration
depth of the ions in the substrate. The bombarded face of the
substrate is than fastened with a face of a receiving substrate or
stiffener. An annealing then makes it possible to obtain a
separation of said thin film from the remainder of the initial
substrate. One then obtains a thin film adhering to the stiffener.
Spec. 1, ll. 16-28.
The Appellants disclose that this method “enables electronic quality
SOI [silicon on insulator] substrates to be obtained.” Spec. 2, ll. 1-2.
However, when this method is carried out on a SiCOI (silicon carbide on
insulator) substrate, the Appellants disclose that the SiC films transferred
onto silicon oxide completely lose their electrical conductive properties and

1 Appeal Brief dated October 13, 2011.
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become completely isolating. Spec. 2, ll. 16-19. The Appellants disclose
that:
It has been shown that the electrical compensation introduced
into the transferred films and responsible for said acquired
isolating property, is linked to the implantation defects created
in the material by the passage of the protons used to carry out
the implantation.
Spec. 2, ll. 19-24; see also App. Br. 3 (loss of electrical conductive
properties is caused by a high concentration of defects).
To overcome the disadvantages of the prior art, the Appellants
propose a manufacturing method “that makes it possible to obtain a film of
semi-conductive material on a support with a residual electrical
compensation, due to the ionic implantation, that is negligible.” Spec. 5, ll.
20-25.
Claims 18 and 19 are illustrative of the subject matter on appeal and
are reproduced below from the Claims Appendix of the Appeal Brief. The
limitations at issue are italicized.
18. A method for transferring an electrically active SiC thin
layer from an initial SiC substrate, the method comprising:
determining hydrogen ion implantation conditions
including dose, energy and implantation current that create a
buried, embrittled film at a depth, with respect to an implanted
face of the initial SiC substrate, wherein an implantation defect
concentration in a first 500 nm of implanted SiC is lower than
9.1020 atoms/cm3,[2] and a number of acceptor defects
compatible with desired electrical properties of an active thin
layer is obtained;
performing hydrogen ion implantation through a face of
the initial SiC substrate, under said determined hydrogen ion
implantation conditions, and creating said buried, embrittled
film;

2 We understand “9.1020” to be alternative notation for 9x1020.
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fastening the face of the initial SiC substrate after
implantation to a face of a target substrate, to obtain a structure;
separating the structure in two parts at a level of the
buried embrittled film; and
thinning a layer of the SiC remaining fastened to the
target substrate to a thickness lower than 500 nm.
19. The method of claim 18, wherein the performing
hydrogen ion implantation creates said buried embrittled film
at an average implantation depth greater than 1100 nm.
The claims on appeal stand rejected as follows: claims 10-12 and 18
under 35 U.S.C. § 103(a) as unpatentable over Goesele3 in view of
Sakaguchi4; claim 13 under 35 U.S.C. § 103(a) as unpatentable over Goesele
in view of Sakaguchi and further in view of Maleville5; and claims 19-21
under 35 U.S.C. § 103(a) as unpatentable over Goesele in view of Sakaguchi
and further in view of Mitani.6
B. DISCUSSION
There is no dispute on this record that Goesele discloses a method for
transferring an electrically active SiC thin layer from an initial SiC substrate
comprising the steps of performing hydrogen ion implantation through a
face of the initial SiC substrate to create a buried, embrittled film, fastening
the face of the initial SiC substrate to a face of a target substrate to obtain a
structure, and separating the structure in two parts at a level of the buried
embrittled film. Ans. 5;7 App. Br. 6.

3 US 6,150,239, issued November 21, 2000.
4 US 2003/0170990 A1, published September 11, 2003.
5 US 6,403,450 B1, issued June 11, 2002.
6 US 7,084,046 B2, issued August 1, 2006.
7 Examiner’s Answer dated November 28, 2011.
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The Examiner finds that Goesele does not disclose the “determining”
and “thinning” steps recited in claim 18 (i.e., the first and last steps of the
claimed method, respectively). Ans. 5. Nonetheless, the Examiner finds
that Goesele discloses that:
[a] thin film layer is formed to a thickness of 0.58 µm (580 nm),
and the hydrogen concentration at the maximum (i.e. at a depth
of 580 nm) is approximately 6x1021 atoms/cm3 [see col. 10,
lines 22-29], but do [sic, does] not disclose the concentration at
a depth of 500 nm. However, it is known in the art that it is
desirable to minimize the implantation defect concentration in
implanted semiconductor thin films; defects and deformations
in an active layer due to the implantation of atoms may cause
quality issues and may be difficult to repair with a healing
anneal.[8] Therefore, the process of optimizing to determine the
optimal implantation dose, energy and current in order to
minimize the implantation defect concentration and the number
of acceptor defects compatible with the desired electrical
properties of the active layer is within reasonable and routine
optimization processes performed by one of ordinary skill in the
art.
Ans. 5; see also Ans. 10.
As for the thinning step recited in claim 18, the Examiner concludes
that it would have been obvious to one of ordinary skill in the art “to thin the

8 We understand this finding to be based on the Appellants’ disclosure in the
Specification that a high concentration of defects affects the electrical
properties of the film. Spec. 2, ll. 19-24; Spec. 3, l. 9-4, l. 11; see also App.
Br. 3 (loss of electrical conductive properties is caused by a high
concentration of defects). The Examiner does not include the Appellants’
admitted prior art in the statement of the rejection. See In re Hoch, 428 F.2d
1341, 1342 n. 3 (CCPA 1970) (“Where a reference is relied on to support a
rejection . . . there would appear to be no excuse for not positively including
the reference in the statement of the rejection.”). Nonetheless, the statement
of each rejection on appeal has been amended to add this admitted prior art,
and the rejections on appeal have been designated new grounds of rejection.
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layer in order to provide a uniform thin active layer on the target substrate”
based on the teachings of Sakaguchi. Ans. 6.
The Appellants argue that after the last step in Goesele’s method (i.e.,
after the structure has been separated in two parts), the resulting thin layer
does not need to be thinned because Goesele uses the Smart Cut process
described in column 2, lines 10-27 of Goesele. App. Br. 6.
Contrary to the Appellants’ argument, Goesele discloses that after the
structure has been separated, the transferred silicon layer is subjected to a
light polishing and/or a thermal oxidation step. Goesele, col. 11, ll. 16-19;
compare Spec. 13, ll. 7-9 (the thin film is thinned down by ion beam etching
or by thermal oxidation). Moreover, Sakaguchi discloses that the Smart Cut
process includes a polishing step. Sakaguchi ¶ 25; see also Sakaguchi ¶ 251
(transferred thin film is flattened and uniformly thinned).
The Appellants also argue that the first and last steps recited in claim
18 are “linked together, wherein the implantation and the thinning are based
on the first 500 nm being suitable for the desired electrical properties.” App.
Br. 7. The Appellants argue that “Goesele does not disclose or suggest
making a thin film using the concept linking the first and last steps of Claim
18.” App. Br. 7.
This argument is not persuasive of reversible error because it is not
based on a limitation appearing in claim 18. In re Self, 671 F.2d 1344, 1348
(CCPA 1982). Claim 18 does not contain language that links the
implantation and thinning steps. In this regard, we note that claim 18 merely
recites the step of “thinning a layer of the SiC remaining fastened to the
target substrate to a thickness lower than 500 nm.” App. Br. 14.
Nonetheless, we find that any link between the first and last steps of
the claimed method would have been suggested by the prior art of record.
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At the time of the Appellants’ invention, it was known that a high
concentration of defects would affect the electrical properties of the
transferred film. Spec. 2, ll. 19-24; Spec. 3, l. 9-4, l. 11; see also App. Br. 3
(loss of electrical conductive properties is caused by a high concentration of
defects). Thus, one of ordinary skill in the art would have been motivated to
reduce both the implant defect concentration during implantation and the
thickness of the transferred film after implantation to achieve the desired
electrical properties. To this end, the Examiner finds that Goesele teaches
that implant defect concentration may be controlled by adjusting
implantation conditions, such as implantation dose, energy, and current.
Ans. 5; see also In re Boesch, 617 F.2d 272, 276 (CCPA 1980) (“discovery
of an optimum value of a result effective variable in a known process is
ordinarily within the skill of the art”).
The Appellants do not dispute that Goesele teaches that implant defect
concentration is a result-effective variable at a particular depth. The
Appellants, however, argue that Goesele does not recognize that “the
variable of defect concentration . . . over an entire zone (as opposed to at a
single depth)” is a result effective variable. App. Br. 8 (emphasis added).
The Appellants’ argument is not persuasive of reversible error.
Goesele discloses:
Molecular hydrogen H2+ ions are then implanted into the
boron-implanted silicon substrate at 129 keV with a dose of
5x1016 cm-2 so that the concentration maximum of the two
distributions of implanted boron and hydrogen are aligned with
respect to the position of the maximum in their concentration
depth distribution. The hydrogen concentration in the

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maximum is approximately 6x1021 cm-3 at a depth of
approximately 0.58 µm.
Goesele, col. 10, ll. 22-29 (emphasis added). We find that this disclosure
would have taught one of ordinary skill in the art that the defect
concentration in Goesele varies throughout a zone as claimed, with the
maximum hydrogen concentration being approximately 6x1021 cm-3 at a
depth of approximately 0.58 µm.
As to claim 19, the Appellants do not direct us to any error in the
Examiner’s finding that Mitani teaches that the depth of ion implantation is
adjustable by adjusting the ion energy, and more specifically, the
acceleration voltage. Ans. 11; Reply Br. 7-8.9 Rather, the Appellants argue
that “[t]he Examiner provides no technical explanation as to why a substrate
that is at least 1100 nm thick would need to be polished/thinned down to be
less than 500 nm merely to remove some alleged undesirable surface
roughness.” Reply Br. 7-8.
As discussed above, at the time of the Appellants’ invention, it was
known that a high concentration of implantation defects would affect the
electrical properties of a transferred SiC film. Spec. 2, ll. 19-24; Spec. 3, l.
9-4, l. 11; see also App. Br. 3 (loss of electrical conductive properties is
caused by a high concentration of defects). Thus, one of ordinary skill in the
art would have been motivated to thin Goesele’s transferred film to a
thickness that results in the desired electrical properties. See Ans. 8 (“it
would have been obvious to one of ordinary skill in the art to control the ion
implantation and thinning depths in order to provide a thin film to the
required specifications”).

9 Reply Brief dated January 30, 2012.
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Finally, the Appellants contend that “[t]he claimed ‘wherein an
implantation defect concentration in a first 500 nm of implanted SiC lower
than 9.1020 atoms/cm3’ is critical as it determines the resulting thin film with
the desired electrical properties.” App. Br. 7. The Appellants, however,
have not directed us to any evidence demonstrating that the claimed
implantation defect concentration produces an unexpected result. See In re
De Blauwe, 736 F.2d 699, 705 (Fed. Cir. 1984) (unexpected results must be
established by factual evidence; mere argument does not suffice).
Based on the foregoing, the weight of the evidence of record supports
a conclusion of obviousness under 35 U.S.C. § 103(a). Therefore, the
§ 103(a) rejections are affirmed. The affirmed rejections, however, are
designated new grounds of rejection because the statement of each rejection
on appeal has been amended to include the Appellants’ admitted prior art.10
See n.6, supra.
C. DECISION
Claims 10-12 and 18 are rejected under 35 U.S.C. § 103(a) as
unpatentable over the combination of Goesele, Sakaguchi, and the
Appellants’ admitted prior art.
Claim 13 is rejected under 35 U.S.C. § 103(a) as unpatentable over
the combination of Goesele, Sakaguchi, the Appellants’ admitted prior art,
and Maleville.
Claims 19-21 are rejected under 35 U.S.C. § 103(a) as unpatentable
over the combination of Goesele, Sakaguchi, the Appellants’ admitted prior
art, and Mitani.

10 Appellants’ Specification, page 1, line 13-page 5, line 17.
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This decision contains new grounds of rejection under 37 C.F.R.
§ 41.50(b) which provides that “[a] new ground of rejection . . . shall not be
considered final for judicial review.”
37 C.F.R. § 41.50(b) also provides that the Appellants, WITHIN
TWO MONTHS FROM THE DATE OF THE DECISION, must exercise
one of the following two options with respect to the new grounds of
rejection to avoid termination of the appeal as to the rejected claims:
(1) Reopen prosecution. Submit an appropriate
amendment of the claims so rejected or new evidence relating
to the claims so rejected, or both, and have the matter
reconsidered by the examiner, in which event the proceeding
will be remanded to the examiner. . . .
(2) Request rehearing. Request that the proceeding be
reheard under § 41.52 by the Board upon the same record. . . .
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).
AFFIRMED
(37 C.F.R. § 41.50(b))

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