Ex Parte Yue

Board of Patent Appeals and Interferences

Jul 31, 2008

10812355 (B.P.A.I. Jul. 31, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE
_______________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_______________

Ex parte HONGYU YUE
______________

Appeal 2008-3341
Application 10/812,355
Technology Center 1700
_______________

Decided: July 31, 2008
_______________

Before BRADLEY R. GARRIS, CHARLES F. WARREN, and
ROMULO H. DELMENDO, Administrative Patent Judges.

WARREN, Administrative Patent Judge.

DECISION ON APPEAL
Applicant appeals to the Board from the decision of the Primary
Examiner finally rejecting claims 1 through 5 and 7 through 13 in the Office
Action mailed June 7, 2006. 35 U.S.C. §§ 6 and 134(a) (2002); 37 C.F.R.
§ 41.31(a) (2006).
We affirm the decision of the Primary Examiner.

Appeal 2008-3341
Application 10/812,355
Claims 1 and 13 illustrate Appellant’s invention of a method for
achieving a target trim amount of a feature on a substrate in a chemical oxide
removal process, and are representative of the claims on appeal:
1. A method for achieving a target trim amount of a feature on a
substrate in a chemical oxide removal process comprising:
performing a chemical oxide removal process using a process recipe
including a first reactant, a second reactant, an inert gas and a process
pressure in order to acquire trim amount data as a function of a variable
parameter, while maintaining at least one constant parameter constant,
wherein said variable parameter is one of a first group of parameters
including an amount of said first reactant, an amount of said second reactant,
and a process pressure, and said at least one constant parameter different
from said variable parameter is one of a second group of parameters
including an amount of said first reactant, an amount of said second reactant,
and a process pressure;
determining a relationship between said trim amount data and said
variable parameter;
using said target trim amount and said relationship to determine a
target value for said variable parameter;
chemically treating said feature on said substrate by exposing said
substrate to said process recipe using said target value of said variable
parameter and said at least one constant parameter; and
substantially removing said target trim amount from said feature.
13. A method for performing a chemical oxide removal process using
a process recipe to achieve a target trim amount of a feature on a substrate
comprising:
determining a relationship between trim amount data and a partial
pressure of a gas specie and an inert gas for said process recipe;
setting said target trim amount;
using said relationship and said target trim amount to determine a
target value of said partial pressured of said gas specie and said inert gas;
adjusting said process recipe according to said target value for said
partial pressure of said gas specie and said inert gas; and
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chemically treating said feature on said substrate by exposing said
substrate to said process recipe
The Examiner relies upon the evidence in these references (Ans. 2):
Natzle US 2004/0097047 A1 May 20, 2004
Newton US 2004/0099377 A1 May 27, 2004
Tomoyasu US 2004/0185583 A1 Sep. 23, 2004
Doris US 2004/0241981 A1 Dec. 2, 2004
Appellant requests review of the following grounds of rejection under
35 U.S.C. § 103(a) advanced on appeal (Br. 6-71):
claims 1 through 5 and 7 through 13 over Tomoyasu (Ans. 3);
claim 1 through 3 and 7 through 13 over Natzle in view of Tomoyasu or
Newton (Ans. 5); and
claim 4 and 5 over Natzle in view of Tomoyasu or Newton as applied to
claim 1, further in view of Doris (Ans. 5).
Appellant argues the claims in each ground of rejection as a group,
with additional argument with a respect to independent claims 1 and 13 in
the first two grounds. Thus, we decide this appeal based on claims 1, 13,
and 4. 37 C.F.R. § 41.37(c)(1)(vii) (2006).
The principal issues in this appeal are whether the Examiner has
carried the burden of establishing a prima facie case in each of the grounds
of rejection advanced on appeal.
The plain language of claim 1 specifies a method comprising at least
the steps, inter alia, of analysis of any chemical oxide removal process
(COR) recipe including at least the parameters of any first reactant, any
second reactant, any inert gas and any process pressure, by performing the
recipe to acquire trim amount data as a function of any variable recipe
parameter, other than inert gas, while holding at least one other recipe
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Application 10/812,355
parameter, other than inert gas, constant; determining any relationship
between the variable parameter and the trim amount data; using the
relationship along with a target trim amount for any feature on any substrate
to determine a target value for the variable parameter in applying the recipe
to the substrate. The plain language of claim 13 specifies a method
comprising at least the steps, inter alia, of determining any relationship
between trim amount data and the parameters partial pressure of any gas
specie and any inert gas of any COR recipe; using the relationship and any
target trim amount to determine target values for the two parameters; and
adjusting the recipe accordingly.
We find Tomoyasu would have disclosed to one of ordinary skill in
this art a method of operating a COR processing system which includes,
inter alia, “performing at least one of setting, monitoring, and adjusting one
or more chemical process parameters” for the system comprising “at least
one of a chemical treatment processing pressure, . . . [a system component]
temperature, and a chemical treatment gas flow rate; [and] processing the
substrate . . . using the one or more chemical process parameters.”
Tomoyasu, Abstract and ¶ 0007; see also ¶¶ 0055-0056 and 0059. The
system includes a COR module in which the COR reaction product is
formed and a post heat treatment chamber in which the reaction product is
evaporated. Tomoyasu, e.g., ¶¶ 0052, 0057-0058, and 0061.
The COR processing system has a number of components which
provide process targets, recipe parameters, data gathering and analysis,
including algorithms, and adjustment of the COR recipe applied to the

1 We have numbered the pages of the Brief beginning with the title page.
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substrate. Tomoyasu, e.g., ¶¶ 0029-0054 and 0075-00127, and Figs. 1-5.
The system components establish the initial state of the wafer and the target
state of the wafer with respect to critical dimensions, and uses the difference
to “predict, select, or calculate a set of process parameters to achieve the
desired result” with respect to that dimension. Tomoyasu ¶¶ 0063-0069 and
0085.
The system components “can compute a predicted state for the wafer
based on the input state, the process characteristics, and a process model,”
including “a trim rate model [that] can be used along with a processing time
to compute a predicted trim amount” and “an etch rate model can be used
along with a processing time to compute an etch depth,” using a number of
models. Tomoyasu ¶¶ 0072-0074; see also ¶ 0062. The system components
use “measured actual process results . . . compared with the predicted
process results in order to determine a correction to the process model,” as
well as “[m]odel updates . . . by running monitor wafers, varying the process
settings and observing the results” to update models. Tomoyasu
¶¶ 0077-0080.
Tomoyasu discloses an embodiment in which the COR recipe includes
“a process gas comprising HF [(hydrogen fluoride)] and NH3” (ammonia), a
processing pressure, gas flow rates, and system component temperature.
Tomoyasu ¶¶ 0059-0060. The system includes a “process model [that] not
only provides input parameters for gas flow rates but also provides input
parameters for gas flow rate ratio.” Tomoyasu ¶ 0088. Tomoyasu illustrates
chemical treatment system 1220 as including “delivery of a heat transfer gas
. . . to the backside of substrate 1242 via a backside delivery system,”
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wherein “the heat transfer gas . . . can comprise an inert gas such as helium
[(He)], argon [(Ar)], . . . a process gas such as CF4, . . . , or other gas such as
oxygen, nitrogen, or hydrogen.” Tomoyasu ¶ 0195 and Figs. 15 and 16.
Tomoyasu further illustrates chemical treatment system 1220 as including “a
gas distribution system 1260 for distributing a process gas comprising at
least two gases,” wherein “[t]he process gas can, for example, comprise
NH3, HF, H2, O2, CO2, Ar, He, etc.” Tomoyasu ¶ 0200 and Figs. 15, 16, and
18.
We find Natzle would have disclosed to one of ordinary skill in this
art a process of making MOSFET devices which includes a COR
precleaning step that employs vapors of HF and NH3 as reactants to form a
COR adsorbed reactant film under low pressure on silicon oxide as a self-
limiting etch to strip the silicon oxide from a substrate, wherein the gas flow
is controlled by valves and an exhaust pump. Natzle, e.g., Abstract and
¶¶ 0002, 0014, and 0037-0038. The COR adsorbed reactant film remains on
the substrate surface while the vapor pressure of NH3 and HF is near the
vapor pressure at the temperature of the apparatus, and a reaction product
comprising ammonium hexafluorosilicate ((NH4)2SiF6) is formed under the
reactant film. Natzle, e.g., ¶¶ 0039-0042. The reaction product can be
removed by evaporation in a heated chamber. Natzle, e.g., ¶ 0046.
The amount of silicon oxide removed from the substrate “is a function
of the substrate temperature, composition and residence time of the adsorbed
reactant film,” and “[f]actors influencing the amount removed per unit time
include the vapor pressure of the reactant at the temperature of the substrate .
. . ; the amount of reactant or the rate of reactant admitted to the COR
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chamber . . . ; the speed of [the vacuum] pump . . . ; and the reaction rate
between the adsorbed reactant film . . . and the . . . .silicon oxide layer,” all
of which can be regulated. Natzle, e.g., ¶ 0042-45. “The self-limiting
thickness [of the adsorbed layer] can be tuned by changing the reaction
conditions,” including pressure, temperature in the reaction chamber, and the
amount and mixture of reactive gases, each of which is controlled by
separate feed lines. Natzle, e.g., ¶¶ 0047-0051 and 0106-0113.
We find Newton would have disclosed to one of ordinary skill in this
art a COR process wherein a mixture of a first fluid, NH3, and a second
fluid, HF, forms an adsorbed layer of ammonium bifluoride (NH5F2) on
silicon oxide that reacts with the silicon oxide to form a self-limiting
etchable layer of (NH4)2SiF6 that can be removed by thermal desorption.
Newton, e.g., Abstract and ¶ 0026. In addition to thermal desorption, the
layer of (NH4)2SiF6 can be removed by rinsing in a solvent, such as water.
Newton ¶ 0030.
A stoichiometric number of moles of HF to NH3 is reacted to obtain
NH5F2, providing a molar ratio of the gases which controls the amount of
silicon oxide that is etched, and thus should be provided uniformly and
homogeneously on the substrate being etched. Newton, e.g., ¶¶ 0027-0032,
0050, and 0057. Newton discloses an apparatus in which fluid feed lines 97,
99 regulate the flow of “[t]he first fluid [which] may comprise, inter alia,
ammonia . . . and the second fluid [which] may comprise inter alia, hydrogen
fluoride,” with the fluid feed lines “alternatively provided with inter alia
Argon or nitrogen gas.” Newton, e.g., ¶ 0033 and Figs. 1-2; see also ¶
0074. The thickness of the self-limiting etchable layer can be controlled
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such that a specific etch rate change/minute can be directly proportional to
temperature. Newton, e.g., ¶¶ 0047 and 0050. “A thickness of the self-
limiting etchable layer . . . was controlled by varying the temperature of the
workpiece . . . resulting in controlling a reaction temperature between the HF
and NH3, or by altering the HF:NH3 stoichiometry,” and [i]t was determined
that a change of 1AºC. equals 17 Â,,<< of etch rate change/minute” when
the workpiece temperature was maintained “from about -10 to about
90ºC.” Newton ¶ 0073.
We find Doris would have disclosed to one of ordinary skill in this art
a COR process wherein a mixture of HF and NH3 forms a solid reaction
product with silicon oxide that can be removed by evaporation and rinsing
the structure in water. Doris ¶¶ 0045-46.
We determine the Examiner has made out a prima facie case of
obviousness with respect to each of the grounds of rejection based on the
Examiner’s findings from the applied references and the conclusions based
thereon as set forth in the Answer (Ans. in entirety), and remain of that
opinion upon reconsideration of the record as a whole in light of Appellant’s
contentions. We add the following to the Examiner’s position for emphasis.
Considering first the ground of rejection of claims 1 and 13 over
Tomoyasu alone, the Examiner concludes from the teachings with respect to
the COR process and the reactant gases therein that one of ordinary skill in
this art would have found in Tomoyasu, that it would have been obvious to
this person to include an inert gas, such as Ar, with the reactant gases NH3
and HF to achieve a target trim amount. Ans. 3. The Examiner further
concludes it would also have been obvious to this person from the teaching
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of the reference that the process parameters of the flow rate of at least two
reactant gases, the flow rate of inert gases, and the partial pressure exerted
by the gases are result-effective variables. Thus, this person would have
analyzed data obtained from routine experimentation using variable and
constant process parameters to select and adjust COR recipes in conjunction
with trim amount data and the variable parameter to obtain optimal results
with respect to predictable target trim amounts when the recipe is applied to
a substrate. Ans. 3-4.
Appellant submits that the teachings of Tomoyasu cannot be
construed to correspond to the limitations of claims 1 and 13 because “the
mere discussion of different modeling techniques even when coupled with a
listing of gases that can make up the process gas” would not have led one of
ordinary skill in this art to the claimed relationships. Br. 10-11. Appellant
contends Tomoyasu does not disclose acquiring “trim amount data as a
function of a variable parameter while maintaining at least one constant
parameter constant” and determining “a relationship between the trim
amount data and said variable parameter” as required by claim 1. Br. 10.
Appellant also contends Tomoyasu does not disclose “a relationship between
trim amount data and a partial pressure of a gas specie and an inert gas” and
“using the relationship to determine a target value of” these parameters as
specified in claim 13. Id. Appellant contends Tomoyasu discloses an inert
gas, e.g., Ar, “in connection with the orifice configurations of the gas
distribution system [in ¶ 200] and the possible use of a heat transfer gas” in ¶
0195, and thus, not as a process parameter or contributing part of the partial
along with a gas specie. Br. 11.
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We cannot subscribe to Appellant’s contentions with respect to the
teachings and inferences one of ordinary skill in this art would have found in
Tomoyasu. We find Tomoyasu would have conveyed to this person that the
at least two process gases used in the COR recipes are not limited to reactant
gases, such as HF and NH3, but includes inert gases, such as Ar, and both
reactant gases and inert gases can be combined for distribution in
Tomoyasu’s COR processing system, as the Examiner points out. Ans. 8;
see also above pp. 5-6. In this respect, and contrary to Appellant’s
contentions, we determine this person would have readily distinguished
between the use of Ar as a process gas and as a component in a heat transfer
gas in the teachings of Tomoyasu.
We determine this person would have known that the use of inert gas
adjusts the flow and amount of a reactant gas in a system, and in this
relationship, each gas provides a partial pressure as the Examiner points out.
Ans. 9. Thus, this person would have reasonably inferred that Tomoyasu
includes combinations of reactant and inert gases in the “processing
pressure” and “flow rate” chemical process parameters that are among those
set, monitored, and adjusted in predicting, selecting and calculating a set of
process parameters for a COR recipe to achieve a desired critical dimension
by removing a trim amount of silicon oxide from a substrate.2

2 It is well settled that a reference stands for all of the specific teachings
thereof as well as the inferences one of ordinary skill in this art would have
reasonably been expected to draw therefrom, see In re Fritch, 972 F.2d
1260, 1264-65 (Fed. Cir. 1992); In re Preda, 401 F.2d 825, 826 (CCPA
1968), presuming skill on the part of this person. In re Sovish, 769 F.2d 738,
743 (Fed. Cir. 1985).
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We agree with Appellant that Tomoyasu does not specifically disclose
holding one parameter constant while varying another parameter in
analyzing a particular COR recipe to determine a relationship between the
variable parameter and the trim amount data in setting a target value for the
variable parameter in the recipe. However, one of ordinary skill in this art
would have routinely followed the well known Scientific Method of holding
one factor constant while varying another factor in studying a process
comprising more than one result effective variable. Indeed, this person in
routinely following Tomoyasu would have set, monitored, and adjusted one
or more result effective variables of a COR recipe, including process gas
flow rates and partial pressure thereof for a combination of reactant and inert
process gases by acquiring trim amount data over time by varying the
process gas parameter settings to obtain workable or optimum trim rate data
therefor by routine experimentation. See, e.g., In re Boesch, 617 F.2d 272,
276 (CCPA 1980)(“[D]iscovery of an optimum value of a result effective
variable in a known process is ordinarily within the skill of the art.”); In re
Aller, 220 F.2d 454, 456 (CCPA 1955)(“[W]here the general conditions of a
claim are disclosed in the prior art, it is not inventive to discover the
optimum or workable ranges by routine experimentation.”); see also In re
Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003) (“The normal desire of
scientists or artisans to improve upon what is already generally known
provides the motivation to determine where in a disclosed set of percentage
ranges is the optimum combination of percentages.”). This person would
have used the trim rate data, based on the relationship of the trim rate
achieved by varying the process gas parameters over time, along with
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processing time to determine target trim amounts with respect to the process
gas parameters to achieve a critical dimension of a substrate in applying the
adjusted recipe to the substrate as taught by Tomoyasu.
Accordingly, on this record, we are of the opinion that the Examiner
has established that, prima facie, one of ordinary skill in this art routinely
following Tomoyasu alone would have reasonably arrived at the claimed
method for achieving a target trim amount of a feature on a substrate in a
COR process encompassed by claims 1 and 13 without resort to Appellant’s
Specification. See, e.g., KSR Int’l Co. v. Teleflex Inc., 127 S. Ct. 1727,
1740-41 (2007) quoting In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006)
(“[A]nalysis [of whether the subject matter of a claim would have been
obvious] need not seek out precise teachings directed to the specific subject
matter of the challenged claim, for a court can take account of the inferences
and creative steps that a person of ordinary skill in the art would employ.”);
Sovish, 769 F.2d at 743 (skill is presumed on the part of one of ordinary skill
in the art); In re Bozek, 416 F.2d 1385, 1390 (CCPA 1969) (“Having
established that this knowledge was in the art, the examiner could then
properly rely, as put forth by the solicitor, on a conclusion of obviousness
‘from common knowledge and common sense of the person of ordinary skill
in the art without any specific hint or suggestion in a particular reference.’”);
see also In re O’Farrell, 853 F.2d 894, 903-04 (Fed. Cir. 1988) (“For
obviousness under § 103, all that is required is a reasonable expectation of
success.” (citations omitted)).
Turning now to the ground of rejection of claims 1 and 13 over the
combined teachings of Natzle, Tomoyasu, and Newton, the Examiner
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concludes Natzle would have led one of ordinary skill in this art to regulate
the result effective variable parameters of a COR recipe which influence the
amount of silicon oxide removed per unit time including, inter alia, reactant
gas vapor pressure and reactant gas flow rate, by routine experimentation
and use the relationship of trim amount data over time to determine a target
trim amount for the variable parameter in applying the adjusted recipe to a
substrate. Ans. 5-6. The Examiner further concludes this person would
have combined an inert gas with Natzle’s reactive gases as taught by
Tomoyasu and Newton with respect to COR processes. Ans.
5-6.
Appellant contends both Natzle and Tomoyasu do not disclose or
suggest the combination of a reactant gas and an inert gas, relying on
arguments submitted with respect to the ground of rejection over Tomoyasu
alone. Br. 13. Appellant contends Newton discloses only that an inert gas,
inter alia, Ar, may optionally be provided through fluid feed lines 97, 99.
Br. 14. On this basis, Appellant submits the mere mention of inert gases in
Newton would not lead one skilled in the art to “determine the nature of the
relationship between the trim amount and the amount of an inert gas,” and
thus would not suggest the recipe requiring an inert gas of claim 1 and a
relationship between trim amount data and a partial pressure of a gas
reactant and an inert gas as required in claim 13. Br. 14. Br. 14.
We disagree with Appellant’s position with respect to both Tomoyasu
and Newton. We remain of the view that Tomoyasu would have taught one
of ordinary skill in this art that inert gas, including Ar, can be combined with
reactant gases for distribution in Tomoyasu’s COR processing system, and
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would have known that the inert gas adjusts the flow rate and amount of a
reactant gas as well as the processing pressure in the system. See above
pp. 9-10. We determine this person would have further found similar
teaching in Newton’s disclosure that the inert gas provided to fluid feed lines
97, 99 regulates the flow of the reactant gas, varying the HF:NH3
stoichiometry parameter, including partial pressure, and thus controlling the
amount of silicon oxide, that is etched over time to achieve a specific etch
rate per unit of time. Therefore, both Tomoyasu and Newton provide
evidence supporting the Examiner’s position.
Accordingly, on this record, we are of the opinion that the Examiner
has established that, prima facie, one of ordinary skill in this art routinely
following the combined teachings of Natzle, Tomoyasu, and Newton would
have reasonably arrived at the claimed method for achieving a target trim
amount of a feature on a substrate in a COR process encompassed by claims
1 and 13 without resort to Appellant’s Specification. See, e.g., KSR Int’l,
127 S. Ct. at 1740-41 (quoting Kahn, 441 F.3d at 988); In re Keller, 642
F.2d 413, 425 (CCPA 1981)((“[T]he test [for obviousness] is what the
combined teachings of the references would have suggested to those of
ordinary skill in the art.”); Sovish, 769 F.2d at 743; Bozek, 416 F.2d at 1390;
see also O’Farrell, 853 F.2d at 903-04.
With respect to the ground of rejection of claim 4 over the combined
teachings of Natzle, Tomoyasu, Newton, and Doris, Appellant contends only
that Doris does not provide teachings absent from the other references based
on contentions considered above (Br. 15), which does not address the thrust
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of the Examiner’s rejection applying Doris. Ans. 7. Thus, Appellant has not
rebutted the Examiner’s prima facie case of obviousness.
Accordingly, based on our consideration of the totality of the record
before us, we have weighed the evidence of obviousness found in Tomoyasu
alone, the combined teachings of Natzle, Tomoyasu, and Newton, and the
combined teachings of Natzle, Tomoyasu, Newton, and Doris, with
Appellant’s countervailing evidence of and argument for nonobviousness
and conclude that the claimed invention encompassed by appealed claims 1
through 5 and 7 through 13 would have been obvious as a matter of law
under 35 U.S.C. § 103(a).
The Primary Examiner’s decision is affirmed.
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)(iv).
AFFIRMED

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