Ex Parte Srinivasan et al

Patent Trial and Appeal Board

Sep 2, 2016

11600695 (P.T.A.B. Sep. 2, 2016)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR
11/600,695 11/16/2006
63162 7590 09/07/2016
TRASK BRITT, P,CJ MICRON TECHNOLOGY
P.O. BOX 2550
SALT LAKE CITY, UT 84110
Bhaskar Srinivasan
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
ATTORNEY DOCKET NO.
2269-7956US
(06-0641.00/U
CONFIRMATION NO.
5667
EXAMINER
TADAYYONESLAMI, TABASSOM
ART UNIT PAPER NUMBER
1712
NOTIFICATION DATE DELIVERY MODE
09/07/2016 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):
USPTOMail@traskbritt.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte BHASKAR SRINIVASAN and JOHN A. SMYTHE
Appeal2013-006632
Application 11/600,695
Technology Center 1700
Before BRADLEY R. GARRIS, CHUNG K. PAK, and LINDA M. GAUDETTE,
Administrative Patent Judges.
GAUDETTE, Administrative Patent Judge.
DECISION ON APPEAL
Appeal2013-006632
Application 11/600,695
Appellants1 appeal under 35 U.S.C. § 134(a) from the Examiner's decision2
finally rejecting claims 1, 2, 4, 5, 7-14, 16, 18, 19, 25, 27-30, and 32-34. We
have jurisdiction under 35 U.S.C. § 6(b ).
We AFFIRM.
The invention relates to a method of "forming a structure having a high
dielectric constant (k) [(a "high-k structure")] and a low leakage current ... from a
perovskite-type material." Specification filed November 16, 2006 ("Spec.") i-f 1.
The Specification describes "a perovskite-type material [as] having the general
chemical structure of AB03, where A and B are metal cations having different
sizes." Id. i-f 15. Exemplary A cations are barium, strontium, aluminum, or
combinations thereof, and exemplary B cations are titanium, niobium, tantalum, or
combinations thereof. Id. "The high-k structure may be formed by conducting
multiple ALD [(atomic layer deposition)] cycles and multiple anneal cycles, with
each ALD and anneal cycle producing a portion of the high-k structure." Id. i-f 17.
Of the appealed claims, claims 1, 16, and 25 are independent. Claim 1 is
representative of the claimed invention, and is reproduced below:
1. A method of forming a structure, comprising:
forming a high-k structure from a plurality of portions of a
perovskite material having a chemical structure of AB03, wherein A
and B are metal cations and wherein each portion of the plurality of
portions of the perovskite material is formed by:
depositing a plurality of monolayers of the perovskite material
by atomic layer deposition to form a deposited portion of the
perovskite material; and
annealing the deposited portion of the perovskite material
1 Appellants identify the real party in interest as Micron Technology, Inc. Appeal
Brief filed Jan. 15. 2013 ("App. Br."), 5.
2 Final Office Action mailed August 14, 2012 ("Final Act.").
2
Appeal2013-006632
Application 11/600,695
before depositing another portion of the perovskite material by atomic
layer deposition wherein annealing comprises heating the deposited
portion of the perovskite material to a temperature greater than or
approximately equal to a crystalline temperature of the perovskite
material.
App. Br. 32 (Claims Appendix).
The Examiner maintains the following grounds of rejection under 35 U.S.C.
§ 103(a):
1. Claims 1, 2, 4, 10, 14, 16, 25, 30, 32, and 33 are rejected as
unpatentable over Kai (U.S. Patent Publication No. 2006/0249773 Al, published
Nov. 9, 2006) in view of Ahn et al. (U.S. Patent Publication No. 2003/0207032 Al,
published Nov. 6, 2003 ("Ahn")).
2. Claims 7, 9, and 27 are rejected as unpatentable over Kai in view of
Ahn, and further in view of Putoken et al. (U.S. Patent Publication No.
2006/0088660 Al, published Apr. 27, 2006 ("Putoken")).
3. Claims 5, 7-9, 11, 18, and 19 are rejected as unpatentable over Kai in
view of Ahn, and further in view of Xu et al. (U.S. Patent Publication No.
2010/0062150 Al, published Mar. 11, 2006 ("Xu")).
4. Claims 12, 13, 28, and 29 are rejected as unpatentable over Kai in
view of Ahn, Xu, and further in view of Nakanishi (U.S. Patent Publication No.
2004/0092038 Al, published May 13, 2004).3
3 In the Final Office Action, the Examiner refers to Nakanishi as "Naruhiko,"
which is the first name of the inventor. See Final Act. 7; Nakanishi, 1 (75). The
Examiner does not include Xu in the statement of this ground of rejection, but
discusses Xu in the body of the rejection. See Final Act. 6-7. It is clear from the
Appeal Briefthat Appellants understood the rejection to be based on Kai, Ahn, Xu,
and Nakanishi. See App. Br. 23-27. Accordingly, we determine the Examiner's
failure to include Xu in the statement of this ground of rejection is harmless error.
3
Appeal2013-006632
Application 11/600,695
5. Claim 34 is rejected as unpatentable over Kai in view of Ahn, and
further in view of Imai et al. (U.S. Patent No. 5,686,151, issued Nov. 11, 1997
("Imai")).
The Examiner finds Kai discloses the invention as recited in independent
claims 1, 16, and 25, with the exception of a step of annealing the deposited
portion of the perovskite material (claims 1 and 25)/strontium titanate (claim 16)
before depositing another portion thereof by atomic layer deposition as recited in
the independent claims. Final Act. 2. The Examiner finds Ahn discloses a method
of making an integrated circuit in which every mono layer of aluminum oxide, a
high-k material, is annealed prior to deposition of a subsequent layer in order to
maximize dielectric breakdown strength. Id. (citing Ahn i-f 44). The Examiner
finds one of ordinary skill in the art would have been motivated to modify Kai's
method to anneal each layer of perovskite material/strontium titanate prior to
deposition of a subsequent layer based on Ahn' s teaching that this technique helps
to improve dielectric properties. Id. at 3. The Examiner finds one of ordinary skill
in the art reasonably would have expected that Ahn's technique could be used in
Kai's method because Kai's perovskite materials, like Ahn's aluminum oxide, are
high-k materials. Id. The Examiner cites S. Jackschik et al. (Solid Thin Films
425(2003)216-220 ("Jackshik")) and Ring et al. (Journal of Applied Physics (94)4,
(2003), 5982-5989 ("Ring")), as evidence that one of ordinary skill in the art would
have expected Kai's perovskite materials to exhibit the same type of improvements
in dielectric properties as Ahn's aluminum oxide. Id. at 8-9. Specifically, the
Examiner finds Jackschik teaches that annealing aluminum oxide films obtained by
an ALD method "improve[ s] the crystallization and quality of the high dielectric
film and therefore increase[ s] the polarization and dielectric constant and
improve[s] leakage current of the high dielectric film." Id. The Examiner finds
4
Appeal2013-006632
Application 11/600,695
Ring teaches the same type of improvements are achieved in a barium strontium
titanite film (a perovskite-type material (Spec. i-f 15)) by annealing, e.g., an increase
in dielectric constant. Final Act. 9.
Appellants' arguments in support of patentability are directed to similar
limitations in claims 1, 16, and 25. See App. Br. 10-17. Appellants also present
separate arguments in support of patentability of claims 12, 13, 28, and 29, rejected
over the combination of Kai, Ahn, Xu, and Nakanishi (see above-listed ground of
rejection 4). App. Br. 25-27. Appellants do not present separate arguments in
support of patentability of any other dependent claims, but argue the dependent
claims are patentable by virtue of the Examiner's failure to establish a prima facie
case of obviousness with respect to the independent claims. See id. at 15, 18-19,
21-23, and 28-29.
With respect to the independent claims, Appellants argue Ahn' s disclosure is
limited to an aluminum oxide deposition system and dispute the Examiner's
contention that the ordinary artisan would have considered Ahn's teachings
applicable to perovskite materials having a chemical structure of AB03. App. Br.
13, 17; see also, id. at 15 ("[T]he technique of Ahn was developed to overcome
shortcomings of ALD such as slow deposition rates 'particularly as applied to
deposition of aluminum oxide."' (quoting Ahn, Abstract)). Appellants argue
Jackshik's and Ring's teachings that annealing increases the dielectric constant of a
material do not amount to a disclosure or suggestion that Ahn's method of
annealing an aluminum oxide layer prior to deposition of a subsequent layer
thereof would provide the same benefits to layers comprising a perovskite material
having the chemical structure AB03. Id. at 16. Appellants contend one of
ordinary skill in the art would not assume Ahn's method could be applied to
another material simply by virtue of that material having a high-k form, noting that
5
Appeal2013-006632
Application 11/600,695
"[a]s known in the art, properties of materials, including crystallization behavior,
vary based on composition." Id. at 14 (citing J .L. Klamo et al., Manipulation of
the crystallinity boundary of pulsed laser deposited high-k Hf02-Ti02-Y203
combinatorial thin films, 107 J. APPLIED PHYSICS, 054101, 054101-1 (2010);
Margit Zacharias and Peter Streitenberger, Crystallization in the limit of ultra thin
layers-A new crystallization model, 638 MAT. REs. Soc. SYMP. PROC. F6.2.l,
F6.2.2 (2001 )). Appellants contend the Examiner failed to establish a prima facie
case of obviousness because the Examiner did not identify evidence to support a
finding that "the materials of Kai share some relevant property or characteristic
with aluminum oxide" such that the ordinary artisan reasonably would have
expected Ahn' s technique for aluminum oxide to have benefited Kai's material.
Reply Brief filed April 22, 2013 ("Reply Br."), 5.
The Examiner, in response, finds the references cited by Appellants are not
persuasive evidence of patentability because they are unrelated to annealing.
Examiner's Answer mailed Mar. 11, 2013 ("Ans."), 4. The Examiner contends
Appellants have not shown error in the Examiner's finding that, as evidenced by
Ring and Jakschik, the ordinary artisan reasonably would have expected the same
types of improvements to occur in a perovskite material that occur in an aluminum
oxide material upon annealing by virtue of the fact that they are both high-k
dielectric materials. Id.
"[A] reasonable expectation of success, not absolute predictability" supports
a conclusion of obviousness. In re Langi, 759 F.2d 887, 897 (Fed. Cir. 1985).
Kai indicates that aluminum oxide and perovskite materials having the
formula ABQ3 are equally suitable for use in Kai's method of forming a
semiconductor device having a high dielectric constant material film. See Kai i-f
33. The Examiner has provided evidence, i.e., Ring and Jakschik, to support a
6
Appeal2013-006632
Application 11/600,695
finding that the ordinary artisan reasonably would have expected annealing to
provide similar improvements in properties to these materials because they share
the property of being high-k materials. We find, therefore, for the reasons stated
above and in the Final Action and Answer, that a preponderance of the evidence
supports the Examiner's finding that one of ordinary skill in the art would have
been motivated to, and had a reasonable expectation of success in, applying Ahn's
technique of annealing each layer of aluminum oxide material prior to deposition
of a subsequent layer to Kai's method of forming a semiconductor device,
regardless of whether the high-k material used in Kai's method is aluminum oxide
or one of the listed perovskite materials having the formula AB03. Accordingly,
we are not convinced of error in the Examiner's conclusion of obviousness as to
independent claims 1, 16, and 25.
Turning next to separately argued dependent claims 12, 13, 28, and 29, we
note that each of these claims recites: "wherein forming a high-k structure from a
plurality of portions of a perovskite material comprises forming a high-k structure
having a thickness of approximately 15 nm." Claims 12 and 28 further specify "a
dielectric constant of greater than approximately 80." Claims 13 and 29 specify "a
dielectric constant of approximately 120."
Xu "relates to barium, strontium, tantalum and lanthanum precursors having
utility for atomic layer deposition of titanate films useful in the manufacture of
microelectronic devices such as flash memories." Xu i-f 22. Xu describes building
up a layer of strontium titanate to a desired thickness over an electrode on a silicon
substrate by a deposition process conducted through multiple steps of titanium
functionalization, hydroxylation, strontiation and hydroxylation. Id. i-fi-1 40-41. Xu
discloses the thickness of the layer can be of any suitable value and is in a range
from 5 to 500 nm or more in a specific embodiment. Id. i-f 44.
7
Appeal2013-006632
Application 11/600,695
Nakanishi discloses
[a] method for forming a capacitor insulation film having a high
dielectric constant" that includes "depositing an amorphous strontium
titanate film on a bottom electrode, forming a top electrode on the
strontium titanate film and heat treating the strontium titanate film at a
temperature between 500 degrees C. and 650 degrees C. in an inert
gas ambient to crystallize the amorphous strontium titanate film.
Nakanishi, Abstract. Nakanishi discloses that the heat treatment allows
crystallization to proceed, thereby raising the dielectric constant of the film up to
between 130 and 170. Id. i-f 26.
The Examiner contends it would have been obvious to one of ordinary skill
in the art at the time of the invention to have made the structure formed in the
Kai/ Ahn method to a thickness of approximately 15 nm based on Xu' s teaching
that "it is possible to obtain [a] strontium titanate film with thickness of 5-500 nm
or more." Final Act. 7 (citing Xu i-f 44). The Examiner finds Nakanishi teaches a
method of making high-k dielectric material for capacitors including depositing a
strontium titanate film on a substrate. Id. The Examiner finds Nakanishi discloses
that the dielectric constant of the film depends on the degree of crystallization (or
annealing temperature), and that the dielectric constant of the film inherently
effects the capacitance. Id. The Examiner determines it would have been obvious
to one of ordinary skill in the art at the time of the invention to adjust annealing
temperature in the method of Kai/ Ahn/Xu to obtain a structure having a dielectric
constant of about 120 or higher (see claims 12, 28 ("greater than approximately
80"); claims 13, 29 ("approximately 120")), because Nakanishi teaches the
desirability of a dielectric constant in the range of between 130 and 170 and that
dielectric constant is a function of annealing temperature. See Final Act. 7.
Appellants argue "[ t ]he teaching of thicknesses of material in Xu and the
teaching of dielectric constants in Nakanishi does nothing to suggest that a material
8
Appeal2013-006632
Application 11/600,695
having such dielectric constants could be formed at the thickness recited in ...
claims [12, 13, 28, and 29]." App. Br. 26.
A recognition in the prior art that a property is affected by a variable is
sufficient to find the variable result-effective. In re Applied Materials, Inc., 692
F.3d 1289, 1297 (Fed. Cir. 2012). In the present case, the Examiner identified
support in Nakanishi for finding that dielectric constant is a function of annealing
temperature/crystallization. See Final Act. 7 (citing Nakanishi i-f 26, Fig. 2).
Appellants appear to assert that dielectric constant is also a function of film
thickness and that achieving a dielectric constant of greater than 80, or about 120,
at a film thickness of 15 nm as claimed was unexpected. See App. Br. 26.
Appellants, have not identified, however, evidence to support this contention. Nor
do we find any evidence of criticality in the claimed thickness and dielectric
constant ranges in the Specification. Absent such evidence, we are not persuaded
of error in the Examiner's determination that claims 12, 13, 28, and 29 would have
been obvious over the collective teachings of Kai, Ahn, Xu, and Nakanishi.
In sum, based on the above discussion and the fact finding and reasoning
advanced by the Examiner in the Final Rejection, Advisory action mailed
November 19, 2012, and the Answer, we sustain the rejections of claims 1, 2, 4, 5,
7-14, 16, 18, 19,25,27-30,and32-34.
No time period for taking any subsequent action in connection with this
appeal may be extended under 3 7 C.F .R. § 1.13 6( a)( 1 )(iv).
AFFIRMED
9