Ex Parte Flagello

Patent Trial and Appeal Board

Jan 22, 2015

12463679 (P.T.A.B. Jan. 22, 2015)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE PATENT TRIAL AND APPEAL BOARD
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Ex parte DONIS GEORGE FLAGELLO
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Appeal 2013-004379
Application 12/463,679
Technology Center 1700
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Before TERRY J. OWENS, BEVERLY A. FRANKLIN, and
N. WHITNEY WILSON, Administrative Patent Judges.

WILSON, Administrative Patent Judge.

DECISION ON APPEAL

Appellant1 appeals under 35 U.S.C. § 134 from the February 22, 2012,
decision of the Primary Examiner finally rejecting claims 1–10 and 19–28.
We have jurisdiction over the appeal under 35 U.S.C. § 6(b).
We affirm-in-part.

1 The real party in interest is ASML Holding NV (Appeal Br. 2).
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CLAIMED SUBJECT MATTER
Appellant’s invention is directed to a lithographic method in which a
substrate is provided with a layer of a resist and a further layer of a material
on the layer of resist to produce a pattern in the further layer (Abstract). The
pattern defines a space through which an area of the layer of resist may be
exposed to radiation (id.). The distance between features of the pattern
defining the space is shorter than the wavelength of the radiation such that
near-field radiation is generated which propagates into and exposes an area
of the resist (id.). Claim 1 is representative of the claims on appeal and is
reproduced below from the Claims Appendix to the Brief:

1. A lithographic method comprising, on a substrate
provided with a layer of a resist, and a further layer of a
material provided on the layer of resist:
providing a pattern in the further layer, the pattern
defining a space via which an area of the layer of resist may
be exposed to radiation, a distance between features of the
pattern defining the space; and
exposing the area of resist to radiation having a
wavelength greater than the distance between features of
the pattern defining the space, such that near-field radiation
is generated which propagates into and exposes at least a
portion of the area of the resist sufficiently to meet or
exceed an exposure intensity threshold of the resist.

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REJECTIONS
(1) Claims 1, 2, 5–10, 19–26, and 28 are rejected under 35 U.S.C.
§ 102(e) as anticipated by Patel.2
(2) Claim 3 is rejected under 35 U.S.C. § 103(a) as being unpatentable
over Patel and Kim.3
(3) Claims 4 and 27 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Patel and Montgomery.4
With regards to Rejection (1), Appellant makes separate arguments
for the patentability of claims 19, 20, 21, 22, 23, 24, 25, 26, and 28.
Accordingly, we will address these claims individually.

DISCUSSION
After consideration of the evidence of record, and the arguments set
forth by Appellant in the Appeal Brief and the Reply Brief, we affirm the
rejections of claims 1, 2, 4–10, 19, 23, 27, and 28, essentially for the reasons
set forth in the Answer. We reverse the rejection of claims 3, 20, 21, 22, 24,
25, and 26, for the reasons set forth by Appellant in the Appeal Brief and the
Reply Brief. We add the following for emphasis.

REJECTION (1) – ANTICIPATION OVER PATEL
CLAIM 1
With regards to claim 1, the Examiner finds that Patel discloses a
photolithographic method which includes applying a photoresist layer to a

2 Patel et al., U.S. Patent Pub. 2008/0145793 A1, published June 19, 2008.
3 Kim et al., U.S. Patent No. 7,998,661 B2, issued August 16, 2011.
4 Montgomery, U.S. Patent No. 6,258,514 B1, issued July 10, 2001.
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substrate, and coating the photoresist layer with an image modifying
material layer (which corresponds to the claimed “further layer”) (Ans. 5,
citing Patel ¶¶ 14–31, 37, 39, 40, 43, and 53). The Examiner also finds that
the image modifying layer is patterned to form an image modifying pattern
on the photoresist layer, which results in the formation of space between
features of the pattern (id.). The Examiner further finds that Patel discloses
exposing the underlying resist layer which is not masked by the image
modifying layer to radiation having a wavelength which is greater than the
space between features of the image modifying pattern (id.). Finally, the
Examiner finds that the radiation inherently produces near-field radiation
exposure of the exposed portions of the photoresist layer sufficiently to meet
or exceed an exposure intensity threshold of the resist (Ans. 5–6). The Patel
process is illustrated by its FIGS. 1A–1G, annotated versions of which are
reproduced below:

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An annotated version of Patel’s FIGS 1A–1H shows a representation
of Patel’s process.

Appellant makes three arguments urging us to find error in the
anticipation rejection of claim 1: (1) Patel does not clearly and
unmistakably show the use of radiation having a wavelength greater than the
distance between the features of the pattern; (2) Patel does not clearly and
unmistakably disclose near-field radiation being generated, and (3) Patel
does not clearly and unmistakably show that near-field radiation sufficient to
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meet or exceed an exposure intensity threshold is directed towards the
exposed part of the resist layer.
With regards to argument (1) – that Patel does not show the use of
radiation having a wavelength greater than the distance between features of
the pattern – Patel discloses that its preferred radiation wavelength is 193 nm
(¶ 43). The Examiner provides a credible explanation of why the distance
between the features of Patel’s pattern is less than 193 nm, thus meeting the
claimed requirement for the relative size of these two measurements (Ans.
12–13). Appellant does not refute this technical discussion (see Reply Br.
3), and accordingly has not shown reversible error in the Examiner’s finding
that Patel discloses this claim limitation.
With regards to argument (2) – that Patel does not disclose the
generation of near-field radiation - the Examiner provides a technical
explanation to support the finding that Patel inherently teaches the
generation of near-field radiation (Ans. 14). In particular, the Examiner
details that the Patel’s irradiation process is essentially the same as the
irradiation process disclosed in Appellant’s Specification and concludes that
this means that Patel’s process inherently generates near-field radiation as
required by the claims (Ans. 14–16). In response, Appellant argues that
“[n]ear-field radiation arises in specific unique circumstances and is
distinguished from conventional imaging using 193 nm (or other
wavelength) radiation” (Reply Br. 4). However, Appellant does not provide
particular information on what the asserted “specific unique circumstances”
entail, and does not dispute the Examiner’s analysis showing that Patel’s
irradiation process is essentially the same as that disclosed in the
Specification (see Reply Br. 3–5). Appellant does note that in Patel’s
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system the image forming layer is optically transparent, but does not explain
why that would prevent the formation of near-field radiation as set forth in
claim 1 (Reply Br. 4).
Accordingly, we determine that Appellant has not shown reversible
error in the Examiner’s finding that Patel inherently discloses the generation
of near-field radiation.
Finally, with regards to argument (3) – that Patel does not show that
near-field radiation sufficient to meet or exceed an exposure intensity
threshold is directed towards the exposed part of the resist layer – the
Examiner relies on Patel’s FIGS. 1E–1H, in combination with ¶ 40 of Patel’s
specification, to show that some of the resist layer is exposed sufficiently to
the near-field radiation to meet or exceed an exposure intensity. (Ans. 16–
17.) Appellant argues that the Examiner has not shown that the required
exposure was caused by near-field radiation, as opposed to radiation
transmitted through the optically transparent image modifying pattern
(Reply Br. 5–6, citing Patel ¶ 52). We are not persuaded by Appellant’s
argument. First, though Patel does disclose that the image modifying pattern
affects the incident radiation, FIGS. 1E–1H show that portions of the resist
layer which are not covered by the image modifying pattern receive
sufficient radiation to exceed an intensity threshold of the resist layer, as
shown by the annotated versions of FIGS. 1E–1H below:
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An annotated version of Patel’s FIGS. 1E–1H shows that portions of
the resist layer not covered by the image modifying pattern are
exposed to radiation of a sufficient intensity to meet or exceed an
exposure intensity threshold of the resist layer.

As may be seen from the above-annotated version of Patel’s FIGS.
1E–1H, at least some portions of the resist layer which are not covered by
the image modifying pattern are exposed to radiation of sufficient intensity
to meet or exceed an exposure intensity threshold of the resist layer. This is
shown by the fact that some of the uncovered resist layer 14 in FIG. 1E
(identified as areas 14A) is exposed so that it may be soluble in the
photoresist developer solution (Patel ¶ 40). As noted above, the Examiner
has made a sufficient, unrebutted showing that this radiation is near-field
radiation, as required by the claim.
Accordingly, we determine that Appellant has not shown reversible
error in the Examiner’s finding that Patel discloses the generated near-field
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radiation exposes at least a portion of the area of the resist sufficiently to
meet or exceed an exposure intensity threshold of the resist.
In summary, Appellant has not shown reversible error in the
Examiner’s finding of anticipation of claim 1 over Patel, and we affirm that
rejection. As Appellant has not made separate arguments with respect to
claims 2 and 5–10,5 we also affirm the anticipation rejection of those claims.

CLAIMS 19 AND 23
Independent Claim 23 differs from claim 1 primarily in that it requires
that the exposure intensity on the resist layer in part exceeds a threshold
intensity (as set forth in claim 1), and in part does not exceed it. Claim 19
depends from claim 1, and also recites that the exposed portion of the resist
layer includes a portion where the exposure intensity threshold is not
exceeded. In addition to the arguments made in connection with claim 1,
which we considered above and found unpersuasive, Appellant argues that
claims 19 and 23 are also not anticipated because Patel does not show a
portion of the resist for which an exposure intensity threshold has not been
exceeded (Appeal Br. 13–14, 17–18). Appellant relies on Patel’s FIG. 3 in

5 Appellant states that dependent claims 2 and 5–10 are allowable over Patel
for the same reasons as claim 1, and also “for the features they recite
individually” (Appeal Br. 10). However, Appellant provides no specific
arguments with respect to those dependent claims (id.). Therefore, we
decline to consider them separately. See 37 C.F.R. § 41.37(c)(1)(vii) (“A
statement which merely points out what a claim recites will not be
considered an argument for separate patentability of the claim.”). See In re
Lovin, 652 F.3d 1349, 1357 (Fed. Cir. 2011) (“[W]e hold that the Board
reasonably interpreted Rule 41.37 to require more substantive arguments in
an appeal brief than a mere recitation of the claim elements and a naked
assertion that the corresponding elements were not found in the prior art.”)

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support of this argument. However, as pointed out by the Examiner at pages
21–23 of the Answer (and illustrated above), Patel’s FIGS. 1E–1G show that
at least some portions of the resist which are exposed to the near-field
radiation (identified by reference numeral 20) are not exposed to a level
which exceeds an intensity threshold, as they are not soluble in the
photoresist developer solution.
In response, Appellant argues that Patel’s FIG. 1 does not disclose or
teach the sizes of the gaps, and therefore cannot be relied upon), and argues
that Patel’s FIG. 3 does not show a portion of the resist where the threshold
is exceeded and a portion where it is not (Reply Br. 10–11). This argument
is not persuasive because Patel’s FIG. 3 shows radiation intensities which
are variable within the exposed portion of the resist, and FIG. 1 shows that
in some portions of the resist the threshold intensity is exceeded, and in
others it is not.

CLAIM 28
Independent Claim 28 is similar to claim 23, except that claim 28 does
not specifically recite exceeding intensity thresholds, but instead states that
the resist layer is developed or etched so that a portion of the layer from the
exposed area is removed and a portion of the layer from the exposed area
remains. Appellant makes essentially the same arguments with respect to
claim 28 as were made in connection with claim 23 (compare Appeal Br.
10–14 with Appeal Br. 14–17), and we find them unpersuasive for the same
reasons outlined above in connection with claim 23.

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CLAIMS 20 AND 24
Claims 20 and 24, which depend from claims 19 and 23, respectively,
recites that the portion of the resist layer for which the intensity threshold
has not been exceeded is located between at least two portions where the
intensity threshold has been exceeded. The Examiner relies again on Patel’s
FIGS. 1E–1H which show that certain undeveloped portions of the resist
layer (i.e., portions where the intensity threshold has not been exceeded) are
located between certain developed portions (i.e., portions where the intensity
threshold has been exceeded) (Ans. 36–37). However, as shown above in
the annotated reproduction of FIGS. 1E–1H at page 8 of this decision, Patel
does not show an exposed area of the resist layer (i.e., not covered by the
image modifying pattern) where there is a portion in which the exposure
threshold has not been exceeded (so that the resist layer is not soluble and is
not removed during the development process) surrounded by at least two
areas where the exposure threshold has been exceeded (so that the resist is
soluble and removed during the development process).
Accordingly, we find that Appellant has shown reversible error in the
anticipation rejection of claims 20 and 24.

CLAIMS 21, 22, 25, AND 26
Dependent claims 21, 22, 25, and 26 recite that the portion of the
resist layer for which exposure exceeds the intensity threshold of the resist
layer is less than or equal to 10 nm (claims 21 and 25) and that the depth of
the portion for which the exposure intensity threshold has been met or
exceeded is less than or equal to 3 nm (claims 22 and 26). We agree with
Appellant’s arguments – as set forth at pages 19–20 and 23–24 of the Appeal
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Brief and pages 17–19 and 23 of the Reply Brief – that the Examiner has not
shown that Patel discloses these specific dimensions, and reverse the
anticipation rejections of these claims.

REJECTION (2) – OBVIOUSNESS OF CLAIM 3
OVER PATEL AND KIM

Claim 3 ultimately depends from claim 1 and recites that the further
layer is chromium. The Examiner finds that Kim discloses a metal layer
made of chromium which forms a pattern on a photoresist layer (Ans. 7).
The Examiner further finds that a person of skill in the art would have been
motivated to use Kim’s chromium masking layer in Patel’s process because
Kim discloses that the metal layer pattern formed on the photoresist layer
enables the formation of a surface plasmon, during exposure to wavelengths
of light that are greater than the interval between the metal pattern lines,
wherein the surface plasmon effect realizes a high pattern density (id., citing
Kim, col. 1, ll. 20–23 and col. 4, ll. 23–41).
We agree with Appellant that a person of ordinary skill in the art
would not have sought to modify Patel’s process by incorporating Kim’s
chromium masking layer, because Patel explicitly recites that its image
modifying layer (corresponding to Kim’s masking layer) is not optically
opaque (i.e., optically transparent) (Patel ¶ 39). Chromium is optically
opaque, and therefore would not be used in Patel’s system. Accordingly, we
reverse the obviousness rejection of claim 3 over Patel and Kim.

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REJECTION (3) – OBVIOUSNESS OF CLAIMS 4 AND 27
OVER PATEL AND MONTGOMERY

Claims 4 and 27, which depend from claims 1 and 23, recite
applying a silylation process to the exposed area of resist. The Examiner
finds that Montgomery discloses subjecting exposed portions of a resist
layer to a silylation process, and that it would have been obvious to use this
process in Patel’s system because Montgomery discloses that the silylated
portions of the underlying resist, when subjected to etching forms a silicon
dioxide etch mask on the silylated portions only and enables the use of the
formed etch mask as a mask to etch the unsilylated portions during a
subsequent etch process (Ans. 7–8, citing Montgomery, col. 5, ll. 35–55, col.
9, ll. 1–21 and 43–50, and col. 10, ll. 31–50).
In response, Appellant argues that neither reference teaches the
elements recited in the independent claims 1 and 23 (Appeal Br. 28). These
arguments are not persuasive for the reasons set forth above with regards to
claims 1 and 23. Accordingly, we affirm this rejection.

CONCLUSION
We AFFIRM the rejection of claims 1, 2, 4–10, 19, 23, 27, and 28.
We REVERSE the rejections of claims 3, 20, 21, 22, 24, 25, and 26.

No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See
37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED-IN-PART
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