Ex Parte Chen et al

Patent Trial and Appeal Board

Jan 17, 2018

14133821 (P.T.A.B. Jan. 17, 2018)

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.
14/133,821 12/19/2013 Bomy Chen 351913-998590 2325
107446 7590 01/19/2018
DLA Piper LLP (US)
2000 University Avenue
East Palo Alto, CA 94303-2248
EXAMINER
HOANG, TUAN A
ART UNIT PAPER NUMBER
2896
NOTIFICATION DATE DELIVERY MODE
01/19/2018 ELECTRONIC
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.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
patentdocketingus-paloalto@dlapiper.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte BORNY CHEN, CHIEN-SHENG SU,
and NHAN DO
Appeal 2017-002374
Application 14/133,821
Technology Center 2800
Before DONNA M. PRAISS, CHRISTOPHER L. OGDEN, and
SHELDON M. McGEE, Administrative Patent Judges.
PRAISS, Administrative Patent Judge.
DECISION ON APPEAL1
STATEMENT OF THE CASE
Appellant2 appeals under 35 U.S.C. § 134(a) from the Examiner’s
decision to reject claims 1—17. App. Br. 2. We have jurisdiction under 35
U.S.C. § 6(b).
1 In explaining our decision, we refer to the Specification filed Dec. 19,
2013 (“Spec.”), the Final Office Action entered Sept. 11, 2015 (“Final
Act.”), the Appeal Brief filed Mar. 8, 2016 (“App. Br.”), the Examiner’s
Answer entered Sept. 28, 2016 (“Ans.”), and the Reply Brief filed Nov. 22,
2016 (“Reply Br.”).
2 Appellant is the Applicant, Silicon Storage Technology, Inc., and is
identified in the Brief as the real party in interest. App. Br. 1.
Appeal 2017-002374
Application 14/133,821
We AFFIRM.
The subject matter on appeal relates to a self-aligned method of
forming a semiconductor memory array of floating gate memory cells.
Spec. 11. According to the Specification, the need for precise alignment
during manufacturing of the various components of semiconductor floating
gate memory cell arrays, such as source, drain, control gate, and floating
gate, becomes more critical as the smallest lithographic feature is reduced.
Id. 13. Self-alignment is described in the Specification as a well-known
technique for processing steps involving one or more materials such that
features are automatically aligned with respect to one another in a processing
step. Id. 14. Claim 1 below is illustrative (disputed matter italicized):
1. A pair of memory cells, comprising:
a substrate of semiconductor material having a first
conductivity type and a surface;
a trench formed into the surface of the substrate and
including a pair of opposing sidewalls;
a first region formed in the substrate under the trench;
a pair of second regions formed in the substrate, with a
pair of channel regions each in the substrate between the first
region and one of the second regions, wherein the first and
second regions have a second conductivity type, and wherein
each of the channel regions includes a first portion that extends
substantially along one of the opposing trench sidewalls and a
second portion that extends substantially along the substrate
surface;
a pair of electrically conductive floating gates each at
least partially disposed in the trench adjacent to and insulated
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Application 14/133,821
from one of the channel region first portions for controlling a
conductivity of the one channel region first portion;
an electrically conductive erase gate having a lower
portion disposed in the trench and disposed adjacent to and
insulated from the floating gates; and
a pair of electrically conductive control gates each
disposed over and insulated from one of the channel region
second portions for controlling a conductivity of the one
channel region second portion;
wherein any portion of the trench between the pair of
floating gates is free of electrically conductive elements except
for the erase gate lower portion.
App. Br. 11 (Claims App’x).
OPINION
The Examiner determines that appealed claims 1—17 would have been
obvious under 35 U.S.C. § 103(a) over Do et al. (US 8,148,768 B2, iss. Apr.
3, 2012, hereinafter “Do”) in view of Wang et al. (US 2004/0212009 Al,
pub. Oct. 28, 2004, hereinafter “Wang”), Hu et al. (US 2005/0269624, pub.
Dec. 8, 2005, “Hu”), and other secondary references for the reasons stated
on pages 7—16 of the Final Office Action. The Examiner also determines
that claims 1—6 are unpatentable on the ground of non-statutory double
patenting for the reasons stated on pages 3—7 of the Final Office Action.
Appellant argues claims 1—11 and 13—17 as a group and relies on
those same arguments for both the double patenting rejection as well as the
separate rejection of claim 12 under 35 U.S.C. § 103(a). App. Br. 5—9. In
accordance with 37 C.F.R. § 41.37(c)(l)(iv), and in view of the lack of
arguments presented for the subsidiary rejection, claims 2—17 will stand or
fall together with independent claim 1.
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Application 14/133,821
Appellant argues that the Examiner erred in rejecting claim 1 over the
combination of Do, Wang, and Hu because Do includes poly block 50 in the
trench between floating gates 42 and does not suggest omitting poly block
50. App. Br. 6. Appellant also argues that Hu’s teaching that poly block 54
can be omitted where voltage coupling between the floating gates and source
regions are sufficient is limited to the particular embodiment disclosed in
Hu. Id. According to Appellant, Hu’s embodiment is “significantly
different than that in Do” because Hu discloses a broader source region 52
and, therefore, has better voltage coupling at the comers of the trenches than
Do, which has narrower source regions. Id. at 7 (comparing Hu, Fig. 6G
with Do, Fig. 2F). Appellant contends that because Do’s overall voltage
couple would be less compared to that in Hu, the Examiner’s statement that
the source region not extending to the comer of the trench bears no weight
on the strength of the voltage coupling between the gate and the source
region is in error. Id. at 8.
Regarding Wang, Appellant contends that the Examiner’s reliance on
Wang is in error because Wang discloses enhanced capacitance coupling
between the source and floating gate is directed to nitride adjacent these
elements, not between them as stated by the Examiner. Id. at 8—9 (citing
Wang, Fig. 4B).3 According to Appellant, Wang does not suggest to a
skilled artisan to use nitride between the floating gate and the source in Do
for enhanced voltage coupling as the Examiner finds. Id. at 9. Appellant
concludes that Hu and Wang do not provide any modification or suggestion
3 We understand Appellant’s citation to “Fig. 4B, Wu” to be a typographical
error.
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Application 14/133,821
to modify Do to omit poly block 50, therefore, claim 1 is not rendered
obvious by the combination of Do with Hu and Wang. Id.
The Examiner responds that Do’s device would operate as intended if
poly block 50 is omitted as suggested by Hu and voltage coupling was
enhanced as suggested by Wang because Do specifically states that poly
block 50 is provided for “enhanced voltage coupling.” Ans. 3 (quoting Do
7:38-40). The Examiner finds that ‘“enhanced voltage coupling’ implies
that there has already been voltage coupling between the floating gates and
the source regions,” which poly block 50 only enhances. Id. The Examiner
further finds that Do’s control gates 62, floating gates 42, and poly block 50
have equivalent structures in Hu, namely control gates 68, floating gates
118, and poly block 54. Id. (citing Do, Fig. 2F; Hu, Fig. 6G). Figure 2F of
Do and Figure 6G of Hu are shown side by side below:
Figures 2F and 6G are cross sectional views of the semiconductor
structures of Do and Hu, respectively. Do 3:49-50; Hu 126.
Regarding the combination of references, the Examiner responds that
because Hu’s poly block 54 has the same functions and properties as Do’s
poly block 50, it would have been obvious to modify the similar structure of
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Application 14/133,821
Do with a reasonable expectation that Do would also be operable with the
removal of poly block 50. Ans. 4.
Regarding the embodiment taught by Hu, the Examiner finds that Hu
specifically suggests the poly block is not necessary when the voltage
coupling is sufficient. Id. at 5 (quoting Hu 1 85: “[If] the voltage coupling
between floating gates 118 and source regions 52 are sufficient [the]
additional voltage coupling with poly blocks 54, while favorable, is not
necessary.”). The Examiner further finds that Wang provides another
example of how voltage coupling between floating gates and source regions
can be made strong, and that is by using a high-k dielectric material, silicon
nitride, between the floating gates and source region. Id. (citing Wang 174).
The Examiner explains how a skilled artisan would understand Wang’s
method of using a dielectric material with a larger dielectric constant 8 to be
one of a finite number of ways to enhance the voltage couple, or the
capacitance C, between two objects. Id. at 6 (identifying as another option
Hu’s method of increasing the overlapping area by making the source region
larger and the floating gate into the L-shape and a third option as making the
layer of dielectric thinner). Among the three finite options identified by the
Examiner, the Examiner finds that Wang’s option involves only changing
the dielectric material to a high-k dielectric, such as silicon nitride, and does
not require dimensional changes to Do’s device, making it “the most natural
and most obvious solution out of the three.” Id. at 7.
Regarding Hu’s overlapping area between the floating gate and the
source region being larger than the overlapping area between the floating
gate and the source region in Do, the Examiner agrees that the voltage
coupling of Do’s device might be less than that of Hu, but explains that the
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Application 14/133,821
source region extending to the comers of the trench is not relevant to the
voltage coupling strength, but, rather, it is the size of the overlapping area
that matters. Id. at 8.
Regarding Wang’s nitride layer 30 being disposed laterally adjacent to
poly block 42, not above the source region, that Examiner maintains it is the
teaching to use a high-k dielectric material to enhance voltage coupling that
is relied upon, not the details of what elements are being coupled. Id. at 8—9.
In the Reply Brief, Appellant argues that the Examiner has not
provided evidence that (1) Do’s device as otherwise configured would work
as intended; (2) a sufficient voltage coupling exists in the Do device without
poly block 50; (3) “enhanced (additional) voltage coupling provided by poly
block 50 is unnecessary for the device disclosed in Do;” and (4) swapping
oxide with nitride between the floating gate and source region of Do can
overcome the loss of capacitive coupling resulting from removing poly
block 50. Reply Br. 4—6. Regarding the finite ways to enhance coupling,
Appellant argues that there is a fourth way and that is to use the poly block
gate stmcture that Do uses. Id. at 6. Appellant further contends that because
Hu’s floating gate and source both extend to the comers of the trench, they
contribute to the overlapping area and therefore are relevant to voltage
coupling. Id. Finally, Appellants contend that the Examiner erred in relying
on Wang’s teaching to use high k dielectric material because such teaching
was not “considered in context.” Id.
We review the appealed rejections for error based upon the issues
identified by Appellants and in light of the arguments and evidence
produced thereon. Cf. Ex parte Frye, 94 USPQ2d 1072, 1075 (BPAI 2010)
(precedential) (cited with approval in In re Jung, 637 F.3d 1356, 1365 (Fed.
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Application 14/133,821
Cir. 2011) (“[I]t has long been the Board’s practice to require an applicant to
identify the alleged error in the [Ejxaminer’s rejections.”)). We are not
persuaded by Appellant’s arguments that the Examiner reversibly erred in
rejecting claim 1 over the combination of Do, Hu, and Wang for the reasons
stated in the Final Action and Answer. We add the following primarily for
emphasis.
Appellant does not dispute that Do discloses all elements of claim 1
except for the requirement that the portion of the trench between the pair of
floating gates is free of electrically conductive elements other than for the
erase gate lower portion. Final Act. 8—9. Appellant also does not dispute
the Examiner’s finding that Hu discloses a memory array of floating gate
memory cells with a poly block disposed between the two floating gates in a
trench to provide coupling between the source region and the floating gates
and that the poly block can be omitted when the coupling is sufficiently
strong. Final Act. 9; Ans. 3^4. In addition, Appellant does not dispute the
Examiner’s finding that voltage coupling is enhanced or made stronger by
using a dielectric material with a larger dielectric constant and that Wang
discloses enhancing voltage coupling using nitride, which has a larger
dielectric constant than oxide. Ans. 6, 8; Final Act. 9.
Instead, Appellant argues that the teachings of Hu and Wang are not
combinable with the teachings of Do because the teachings of each of Hu
and Wang is limited to some structural aspect that distinguishes the memory
cell from that of Do. For Hu, it is the larger overlap between the source and
floating gate (App. Br. 7); for Wang, it is the position of the nitride layer,
which is not oriented between the floating gate and the source as in Do
(App. Br. 8-9).
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Application 14/133,821
Appellant’s arguments are not persuasive because a prior art reference
is not limited to its specific working examples and may be relied upon for all
that it would have reasonably suggested to one having ordinary skill in the
art. Merck & Co., Inc. v. Bio craft Labs., Inc., 874 F.2d 804, 807 (Fed. Cir.
1989); In re Mills, 470 F.2d 649, 651 (CCPA 1972) (citation omitted).
Appellant’s structural distinctions between Do and the other cited prior art
references also are not persuasive because the Examiner’s rejection is not
based upon bodily incorporating Hu’s and Wang’s structures in the device of
Do. See In re Keller, 642 F.2d 413, 425 (CCPA 1981) (“The test for
obviousness is not whether the features of a secondary reference may be
bodily incorporated into the structure of the primary reference. . . . Rather,
the test is what the combined teachings of the references would have
suggested to those of ordinary skill in the art.”) (citations omitted); In re
Nievelt, 482 F.2d 965, 968 (CCPA 1973) (“Combining the teachings of
references does not involve an ability to combine their specific structures.”).
Appellant’s structural distinction between Hu and Do in terms of the
size of their relative overlaps between the source and floating gate is not
persuasive of error in the Examiner’s finding that Hu more broadly teaches
that a poly block located between floating gates in a trench can be omitted if
there is sufficient voltage coupling between the floating gates and the source
regions. Ans. 3. Appellants do not dispute this finding, just the Examiner’s
application of this teaching to the device of Do. Appellant does not assert
that the proposed modification of Do would have been beyond the
capabilities of a person of ordinary skill in the art. Absent such an assertion,
we “take account of the inferences and creative steps that a person of
ordinary skill in the art would employ,” and find a person of ordinary skill in
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the art would have overcome those difficulties within their level of skill.
KSR, 550 U.S. at 418; see also id. at 421 (“A person of ordinary skill is also
a person of ordinary creativity, not an automaton.”); Ball Aerosol &
Specialty Container, Inc. v. Limited Brands, Inc., 555 F.3d 984, 993 (Fed.
Cir. 2009) (Under the flexible inquiry set forth by the Supreme Court, the
PTO must take account of the “inferences and creative steps,” as well as
routine steps, that an ordinary artisan would employ.).
The Examiner has provided sufficient reasons why a skilled artisan
would have been motivated to modify Do in view of Hu’s teachings. The
Examiner finds that the omission of forming the poly block in the trench of
Do would reduce the number of steps in the process. Final Act. 10. The
Examiner also finds that Do, like Hu, discloses that the poly block is for the
purpose of “enhanced voltage coupling.” Ans. 3 (citing Do 7:38—40); Ans. 4
(citing Hu 1 64). Appellant agrees that “enhanced” means “additional.”
Reply Br. 5. Appellant also does not dispute the Examiner’s finding that
there are a finite number of options for enhancing voltage coupling,
including using a high k dielectric material, such as nitride which Wang
discloses has a higher dielectric constant than oxide. Id. at 6.
Appellant’s contention (id.) that the Examiner has not shown that
swapping nitride for oxide in Do would equal the capacitance lost by
removing poly block 50 in Do’s device is not persuasive of error because
Appellant does not direct us to any evidence that such substitution of the
additional capacitance provided by Do’s poly block 50 with Wang’s nitride
would have been beyond the level of skill of a person having ordinary skill
in the art. In addition, even if the enhanced level of capacitance differs
between the use of a poly block and the use of a high k dielectric material,
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Application 14/133,821
the combination would have been obvious based on this record in view of
the undisputed benefit of omitting the poly block identified by the Examiner.
Final Act. 10. A combination of references may be obvious even if the
combination eliminates a benefit of one of the references. In re Urbanski,
809 F.3d 1237 (Fed. Cir. 2016) (“[T]he Board properly found that one of
ordinary skill would have been motivated to pursue the desirable properties
taught by Wong, even at the expense of foregoing the benefit taught by
Gross.”).
Therefore, we are not persuaded of reversible error in any of the
Examiner’s findings as to Do, Wang, and Hu and the Examiner’s
determination that the claimed method would have been obvious to one of
ordinary skill in the art over the combination of the cited prior art references.
In sum, we affirm the Examiner’s rejection of claim 1 as obvious over
the combination of Do, Hu, and Wang.
Because Appellant relies on the same arguments in response to the
Examiner’s non-statutory double patenting rejection of claims 1—6 over Do,
Hu, and Wang, we likewise sustain the Examiner’s rejection for the same
reasons discussed above.
CONCLUSION
We affirm the Examiner’s decision to reject claims 1—17 as obvious
under 35 U.S.C. § 103(a).
We affirm the Examiner’s decision to reject claims 1—6 for non-
statutory double patenting.
DECISION
We affirm all of the stated rejections in the Examiner’s decision.
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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).
AFFIRMED
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