STC.UNM v. Intel Corporation

Filing 133

MARKMAN RESPONSE BRIEF re 110 Brief filed by STC. UNM. (Attachments: # 1 Exhibit 3 - IEDM Article, # 2 Exhibit 4 - Semiconductor International Article, # 3 Exhibit 5 - 998 Response and Amendment 01141999, # 4 Exhibit 6 - 998 Response and Amendment 05181999, # 5 Exhibit 7 - Declaration of Dr. Chris Mack)(Pedersen, Steven)

Exhibit 5 
Response and Amendment, January 14, 1999

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PATENT

Applicants:

Steven R.J. Brueck et al.

Docket No.:

28516.1100 ,-_~~'7-

Serial No.:

08/932,428

Art Unit:

1752

Filing Date:

September 17, 1997

Examiner:

Jill Hackathorn

TITLE:

METHOD AND APPARATUS FOR EXTENDING SPATIAL
FREQUENCIES IN PHOTOLITHOGRAPHY IMAGES

N./jr~~~

RESPONSE AND AMENDMENT

Assistant Commissioner of Patents
Box: Non-Fee Amendment
Washington, D.C. 20231
Dear Assistant Commissioner:
In response to the Office Action mailed October 14, 1998, of which this Response is
within the shortened statutory three month response period, please amend the above reference
application as follows:

RECEIVED
,1M! (2 S \999

Pag I, line 16,

rePI~tent

~an'IO

Application No. 08/407,067" with -- U.S. Patent No.

L'
. .
Page 1,,7 18 an~Place "(CIP ,filed March 13, 1995)" with ~~.(issued June 2,

5,759,744 --.

"

1: __

1998) --.

pag~ 2yarur22,~ce "divisional filed March 13,1996" with -- a continuing
application was filed

0

J~ 1998 --.

Page 1 . e 25~"

" with -- 5,705,321 --.

Page

" with -- January 6, 1998 --.

~7, replace"

pag~ ~ "arniy 18 of Figure 12B" with -- the array structure of Figure 1 --.

1700

,

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e·
Page 23, lin~~e "8C" with -- 9C --.

pag~rePlace "9B" with --lOB and tOC --.
P~ 8, r

ce "48" with -- 68 --.

IN THE CLAIMS:

Please cancel

c1ai~~2~rejUdiCe to filing one or more claims of similar

subject matter in one or more patent applications.

Please amend the claims as follows:

[
1. (Amended) A method for obtaining a attern contai n high spatial frequencies by
combining nonlinear functions of intensity of at least two e

osures combined with an least one

~""""~"""-01~=""",-,~ ~........,="-,........"="-,=....><.>:""-,-,-=,-,--",-=-.>...:.:..~=,-><o,,,,-su,,,,,r,,-,,e=s
.........

to form three dimensional

patterns comprising the steps of:
coating a substrate with a first photoresist
exposing said first photoresist layer wi
developing said first photoresist lay

to form a first image in said first photoresist layer

ure as a result of a nonlinear res onse of said first

said hotoresist la
photoresist layer:
coating said substrate wi

a second photoresist layer;

otoresist layer with a second exposure;
developing said sec nd photoresist layer to form a second image in said second

osure as a result of a nonlinear
res

e.

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·~
~

[applying thresholdingfumlinearities individually to said first and said second images;

mUltiPIYing..sa~and said second images.]

~~~~~~~ high

combining nonlinear functions of intensity of at least two e

spatial frequencies by

osures combined with an least one

patterns comprising the steps of:
coating a substrate with a first mask material nd a first photoresist layer;
exposing said first photoresist layer with a ust exposure
developing said photoresist to form a fir

image in said first photoresist layer. said first

Ima

hotoresist la
layer;
transferring said first image into aid first mask material, said first mask material
comprising at least one of Si0 2, Si 3N 4 a metal, a polysilicon and a polymer;
coating said substrate with a econd photoresist;
exposing said second phot resist with a second exposure
developing said second p, otoresist layer to form a second image in said second

osure as a result of a nonlinear
res onse of said second
transferring said rst image and said second image into said substrate using a combined
mask including parts

0

said first mask layer and said second photoresist;

removing sai first mask material and said second photoresist.

ethod for increasing spatial frequency of lithographic patterns

depositing a

P7

resist on said materia_l~ _

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exposing a periodic pattern in fd photoresist, said periodic pattern having a pitch Pmin
and a linewidth [substantially] less than Pmij2;
developing said periodic pfm in said photoresist;
transferring said periOdijPattern to said material;
depositing a second ph<;Jtoresist layer on said material;
offsetting said periodic pattern by Pmij2;
repeating [the abov/steps] said exposing. developing and transferring steps, thereby
interpolating new said

pat~rn midway between said pattern.
/

,{

- kC\·

)11.

1'\

(Amended) The method of claim~wherein said [pitch Pmi'; includes at least

about 1/2 of a smallest dimension of said substrate] pattern size avoids overlapping of pattern
features upon..doubling of said frequency.

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~,/ "

·(Amended) The method of

•

clai~furthercomprising the step ofallowing ahout

lOOrun between adjacent said [storage nodes] patterns.

(Amended) The method of

claim\~, wherein said step of depositing a [dielectric]
1\
.

material includes depositing an NO. layer.

r

Please add the following new claims 48 and 49:

'.

48.

(New) The metyb"d of claim 1, wherein a minimum of said spatial frequencies

along at least one direction ~aid first or second image is smaller than 2/'A.

(New) The method of claim 1, wherein said intermediate nonlinear processing
step enables a frequency distribution of said pattern which is altered from frequency distributions
of only said first and said second exposure.

REMARKS

Applicant responds to the Office Action mailed October 14, 1998, of which this Response
is within the shortened statutory three month response period. The Examiner rejects claims 1-7
and 15-40 and the Examiner withdrew claims 8-14 and 41-47 from consideration. Applicant
confirms its election of Group I, namely claims 1-7 and 15-40; however, Applicant asserts that
the election was not made without traverse.
The Examiner objects to the disclosure due to various informalities. As requested by the
Examiner, Applicant amends the specification to reference the appropriate patent and serial
numbers for the patents and patent applications cited in the background on page 1. Because the
Applicant desired to file this Response within the shortened statutory response period to avoid
late fees, Applicant was unable to determIne the application numbers for Page 1, lines 6 and 9;
however, Applicant will provide this information before issuance of the present patent
application.
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Applicant also clarifies page 23, line 5 by amending the specification to indicate that the
pitch of the array of Figure 1 is being produced by the sequence in Figures 9A-9E. Applicant
also amends the specification on page 23, line 23 to clarify that Figure 9C appropriately shows
hard mask 44. Applicant also clarifies page 24, lines 16 and 18 by amending the specification to
indicate that the process is shown in Figures lOB and C and the periodic pattern is indicated by
reference numeral 68.
The Examiner objects to claim 24 under 37 C.F.R. 1.75(c) because. the Examiner asserts
that claim 24 is dependent upon claim 15 which already claims repeating the steps. Because the
Examiner agrees that the repeating step of claim 15 covers the repetition of the steps N times,
Applicant cancels claim 24 to avoid redundancy.
The Examiner next objects to claims 39 and 40 due to insufficient antecedent basis. To
clarify the claim language, Applicant anlends claim 39 by clarifying that the step allows 100nm
between adjacent "said patterns." Applicant also amends claim 40 to conform to claim 27, from
which it depends, by reciting the step of "depositing a material".
The Examiner next

rejec~s

claims 1-3,6, 15,27 and 37 under 35 U.S.c. 112. Applicant

.

respectfully traverses this rejection. The Examiner asserts that the preamble of claims 1 and 6 is
confusing. To clarify the claim language, Applicant amends claim 1 to disclose that the
invention includes "a method for obtaining a pattern containing high spatial frequencies ..." to
further explain that the present invention forms a pattern, wherein the pattern contains high
spatial freque~cies. Applicant similarly amends claim 6 to further clarify claim 6.
The Examiner next states that "applying thresholding nonlinearities" and "multiplying
said first and second images" as recited in claim 1 are unclear. The presently claimed invention
uses nonlinear processes between exposures, and as such, the application of threshold
nonlinearities occurs during the development process with the end result of the process being the
m~ltiplication ~fthe images. Accordingly, to further clarify the claim language, Applicant

amends claim 1 by adding that the "first image containing spatial frequencies greater than those
in an aerial image imposed onto said photoresist layer in said first exposure as a result of a
nonlinear response of said first photoresist layer". Applicant also adds similar language to
clarify the second image description in claim 1. Moreover, Applicant also amends the preamble
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of claim 1 to state that "at least one nonlinear processing step intermediate between the two
exposures". Applicant similarly amends independent claim 6 for the same reasons as set forth
above for further defining claim 1.
The Examiner next states that the phrase "spatial frequencies that are not present in said
exposing steps" is unclear. Applicant asserts that the sequence of steps in claim 1 produces
spatial frequencies that are not in the aerial images of the two exposures. Even for a single
exposure, the resulting spatial frequencies are not in the aerial image. More particularly, the
thresholding nonlinearity of the resist includes harmonics of all of the frequencies present in the
image. For a simple grating and incoherent illumination, the aerial image is 1+Acos(21tx/p)
where A is a constant (vs. position) that depends on the grating frequency (lip). There are only
two frequencies in this aerial image: 1) a de term (zero frequency) and a single high frequency

lip. The final pattern in the resist is

I" B" COS(21Z71X/ +qJ,,)
/p
where B" and qJ" are constants that collectively describe the nonlinear response of the photoresist.
Many frequencies exist including the two in the aerial image (n = 0 and n = 1) as well as many
other higher frequencies (n > 1). The increase in frequency depends on the significant terms,
namely on the ratio BjBo. If there are more frequen.cies in the aerial image, the corresponding
expression has all of the harmonics and combinations of harmonics. For two frequencies
oriented in the same direction, the aerial image is:

where nand m span over negative as well as positive integers. The exact coefficients (B n,III' qJn,lII)
depend on the exposures and the nonlinearities. The important point is that these combinations
arise from the nonlinear processes and are not present in the aerial images.
Accordingly, to clarify the claim language in accordance with the foregoing explanation,
Applicant amends claim 1 to clarify that the "spatial frequencies greater than those in an aerial
image imposed onto said photoresist". Because claim 1 further clarifies the type of spatial

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frequencies, Applicant cancels claim 2 which is now redundant due to the amendments to
claim 1.
The Examiner next objects to claim 3 because the Examiner asserts that the phrase
"spatial frequencies that are larger than 2/1.. in all three spatial directions" is unclear. Applicant
asserts that a maximum spatial frequency supported by optical propagation is 1../2 (as discussed in
the Summary section), wherein the intensity pattern corresponds to the interference of counterpropagating beams. The presently claimed invention alters the frequency distribution of the final
structure by (i) increasing the pattern density in the plane of the wafer to periods less than Al2 in
at least one direction (interpolation of the gratings); and (ii) changing the features of a pattern in
a desirable way without increasing the density such as, for example, round holes to square holes.
To further define the foregoing invention, Applicant cancels claim 3 and adds new claims 48 and
49. New claim 48 sets forth the objective for the interpolation method, while new claim 49 sets
forth both the interpolation and the change of features without the increase of density.
The Examiner next objects to claim 15 because the term "substantially" is vague and
indefinite. Applicant asserts that claim 15 merges two grating patterns to produce a final grating
pattern at twice the spatial frequency. As such, a linewidth less than Pmii2 is used. To clarify the
claim language, applicant eliminates the term "substantially" from the claim element. The
Examiner also states that "repeating the above steps" in unclear. To clarify the language of claim
15, Applicant further defines the repeating step as including "exposing, developing and
transferring steps".
The Examiner next objects to claim 27 because of the terms "critical dimension" and
"much less." To clarify the claim language, Applicant explains that the linewidth should be less
than Pmii2. Moreover, the Examiner objects to the phrase "repeating the above steps N times".
To further clarify the claim language, Applicant sets forth the specific steps which are repeated,
namely the exposing, developing and transferring steps. The Examiner next objects to claim 37
due to the description of the pitch. Upon entry of the foregoing amendments, Applicant amends
claim 37 to recite that the pattern size is small enough such that the doubling of the frequency
would not result in an overlapping of the pattern features. For example, if an object is a linespace pattern with a period p, without any doubling, an equal line-space grating would have a
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linewidth p/2. If the period is doubled, the line width has to be no more than p/4 to allow a full
line and space into each half of the first structure.
The Examiner next rej ects claims 1, 15 and 27 under double patenting over claim 1 of
U.S. Patent No.5,705,321. Applicant respectfully traverses this rejection. Applicant asserts that
very significant differences exist between the presently claimed invention and U.S. Patent No.
5,705,321. The presently claimed invention discloses a nonlinear step such as developing (claim
1) or developing and transferring (claim 15 and 17) between the two exposures. The' 321 Patent
simply discloses multiple exposures in the same level of photoresist without any processing in
between the steps. The foregoing distinction is extensively discussed in the present application
on page 13, line 13 - page 14, line 5.
More particularly, the present invention uses a sequence of at least two optical exposures
separated by some nonlinear processing steps. The method produces images with a spatial
frequency content that is different than that which would have been produced by a conventional
multiple exposure process (which is disclosed in some of the cited art) followed by the nonlinear
processing of developing and pattern transfer. Patterns with higher density which can be
achieved with existing exposure processes, such as the frequency doubling described in Figures
9-11, exemplify the substantial benefits of the presently claimed invention. The presently
claimed invention also changes magnitudes and phases of the Fourier coefficients between the
process described by (expose, expose, nonlinear) and (expose, nonlinear, expose, nonlinear).
Figures 6 and 7 exemplify this result by the demonstration of the round hole to square hole
transition. Both of the patterns have the same spatial frequencies; however, the round (or
elliptical) holes have a distribution of frequencies that radiates outward from the center of
frequency space, while the square holes have frequencies only in the x and y directions
perpendicular to the sides of the holes. The roll-off of the magnitudes of the Fourier coefficients
is a more rapid function of the magnitude of the frequency in the round case than in the square
case.
The Examiner next rejects claims 1,4-7, 15, 17-20,23-27,29-32,35-37, and 39 under 35
U.S.C. 102(e) as being clearly anticipated by Brueck et al. (U.S. Patent No. 5,705,321).
Applicant respectfully traverses this rejection. As stated above, the '321 Patent simply discloses
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multiple exposures in the same level of resist without processing between the steps, while the
present invention claims nonlinear steps such as developing (claim 1); or developing and
transferring (claims 15 and 27) between the two exposures. In the presently claimed invention,
patterns with higher density are achieved with exposure processes such as the frequency doubling
described in Figures 9-11. The' 321 Patent discusses nonlinearities which were used to make the
lines thinner, but the nonlinearities did not increase the density of the structures as shown below:
Aerial image

1

L

Single grating after nonlinear
processes 5 '707'321

Freq. Doubled grating after 5,705,321
and this disclosure.

Moreover, the '321 Patent allows for small lines, but the '321 Patent does not interpolate the
patterns to get a denser pattern. The Examiner asserts that Figures 2 and 3 of the '321 Patent
show that the linewidth is much less than half of the pitch; howev.er, the '321 Patent does not
disclose any method to create a pattern with a fundamental period ofp/2, and instead, the '321
Patent only discloses a fundamental period of p.
The Examiner next rejects claims 2 and 3 under 35 U.S.C. 103(a) as being unpatentable
under Brueck et al. (U.S. Patent No. 5,705,321) in view of Heise et al. (U.S. Patent No.
4,859,548). Applicant respectfully traverses this rejection. Applicant asserts that the Heise
reference refers explicitly to two exposures in the same photoresist level without any
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intermediate nonlinear steps. As discussed above, exposures in the same photoresist level
without any intermediate nonlinear steps doe not allow frequency doubling. The Heise reference
provides for a phase shift between different segments of a grating that is accomplished by a
simple moire interference pattern of two gratings written in the same level of resist. In contrast,
the presently claimed invention includes a nonlinear step between the two exposures.
The Examiner next rejects claims 16,28 and 40 under 35 U.S.C. 103(a) as being
unpatentable under Brueck et al. (U.S. Patent No.5,705,321) and further in view of Gardner et al.
(U.S. Patent No. 5,801,075). Applicant respectfully traverses this rejection. Because claims 16,
28 and 40 depend from independent claims 15,27 and 27, respectively, claims 16,28 and 40 are
differentiated from the cited art for the same reasons as set forth above for differentiating the
independent claims from the cited art.
The Examiner next rejects claims 21 and 33 under 35 U.S.C. 103(a) as being
unpatentable under Brueck et al. (U.S. Patent No. 5,705,321) and further in view of Ausschnitt
(U.S. Patent No. 5,790,254). Applicant respectfully traverses this rejection. Because claims 21
and 23 depend from independent claim 15, claims 21 and 23 are patentably distinct from the
cited art for the same reasons as set forth above for differentiating the independent claims from
the cited art. Moreover, the unique combination of lithographic steps (interferometric for opticai
or imaging interferometric or even proximity printing) and nonlinear processes, as discussed in
the specification on, inter alia, page 20, lines 17-24, is novel and not obvious.
The Examiner next rejects claims 22 and 34 under 35 U.S.C. 103(a) as being
unpatentable under Brueck et al. (U.S. Patent No. 5,705,321) and further in view of Hosono et al.
(U.S. Patent No. 5,486,449). Applicant respectfully traverses this rejection. Applicant asserts
that the Hosono reference uses an image reversal process which includes two exposures
separated by a reversal process that can be nonlinear. However, the reversal process is a "flood
exposure" which does not contain any spatial information (Figure 5, Column 4, lines 30-50). In
contrast, the presently claimed invention includes spatial information in both exposures.
Moreover, because claims 22 and 34 depend from independent claims 15 and 27, respectfully,
Applicant asserts that claims 22 and 34 are differentiated from the cited art for the saine reasons
as set forth above for differentiating the independent claims from cited art.
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The Examiner next rejects claim 38 under 35 U.S.c. 103(a) as being unpatentable over
Brueck et al. (U.S. Patent No. 5,705,321) further in view of Dalton et al. (U.S. Patent No.
5,116,718). Applicant respectfully traverses this rejection. Applicant asserts that, because claim
38 depends upon independent claim 27, claim 38 is distinguished from the cited art for the same
reasons set forth above for differentiating independent claims from the cited art. Moreover, the
presently claimed invention of combining lithographic steps with nonlinear processes is novel
and not obvious; therefore, the use of contact patterning in the present lithographic steps is also
patentably distinct.
Upon entry of the foregoing amendments, Applicant asserts that the present patent
application is now in condition for allowance and respectfully requests a Notice of Allowance.
No new matter is added by the foregoing amendments. If the Examiner has questions related to
this Response or the Patent Application, please do not hesitate to call the undersigned attorney.

Dated: January 14, 1999

SNELL & WILMER L.L.P.
One Arizona Center
400 E. Van Buren
Phoenix, AZ 85004-0001
602-382-6228

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