Ex Parte Pavel et al

Board of Patent Appeals and Interferences

Aug 28, 2009

11467842 (B.P.A.I. Aug. 28, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte ELIZABETH G. PAVEL,
MARK N. KAWAGUCHI,
and JAMES S. PAPANU
____________

Appeal 2009-002463
Application 11/467,842
Technology Center 1700
____________

Decided: August 28, 2009
____________

Before ADRIENE LEPIANE HANLON, CHUNG K. PAK, and
TERRY J. OWENS, Administrative Patent Judges.

PAK, Administrative Patent Judge.

DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134(a) from the Examiner’s
decision finally rejecting claims 1 through 7, 9 through 11, and 13 through
23 (Final Office Action, mailed November 13, 2007), the only claims
pending in the application. We have jurisdiction under 35 U.S.C. § 6(b).
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We REVERSE.
STATEMENT OF THE CASE
The subject matter on appeal is directed to “a method for monitoring
and detecting optical emission endpoint(s), for photoresist stripping and
removal of residue from a substrate” (Spec. 1, para. 0002). Details of the
appealed subject matter are recited in representative claims 1 and 14
reproduced from the Claims Appendix to the Appeal Brief (“App. Br.”),
filed April 14, 2008:
1. A method, comprising:
positioning a substrate comprising a photoresist layer into a
processing chamber;
processing the photoresist layer using a multiple step plasma
process; and monitoring the plasma for a hydrogen optical
emission and an oxygen optical emission during the multiple
step plasma process;
wherein the multiple step plasma process comprises:
removing a bulk of the photoresist layer using a bulk
removal step; and switching to an overetch step in
response to the monitored hydrogen optical emission or the
monitored oxygen optical emission.
14. A method of etching a photoresist layer comprising:
positioning a substrate comprising a photoresist layer into a
processing chamber;
processing the photoresist layer using a multiple step plasma
process; and monitoring the plasma for both by-product optical
emission and a reactant optical emission during the multiple step
plasma process;
wherein the multiple step plasma process comprises:
removing a bulk of the photoresist layer using a bulk removal
step; and switching to an overetch step in response to the
monitored by-product optical emission.

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The Examiner relies on the following evidence to establish
unpatentability of the claims on appeal (Examiner’s Answer (“Ans.”),
mailed June 13, 2008):
Tsang US 5,262,279 Nov. 16, 1993
Ishihara US 2001/0027023 A1 Oct. 4, 2001
Powell US 2002/0135761 A1 Sep. 26, 2002
Hallock US 2002/0151156 A1 Oct. 17, 2002

Appellants request review of the following Examiner’s rejections
(page 3 of Reply Brief (“Reply Br.”), filed August 13, 2008):
1. Claims 1, 5 through 7, 9 through 11, 13, 14, and 17 through 23
under 35 U.S.C. § 103(a) as unpatentable over Ishihara in view of Tsang and
Powell; and
2. Claims 2 through 4, 15, and 16 under 35 U.S.C. § 103(a) as
unpatentable over Ishihara, Tsang, Powell and Hallock.
In rejecting the claims on appeal under 35 U.S.C. § 103, the Examiner
relies on Ishihara for teaching a multiple step plasma process comprising
monitoring the intensity of light emission of hydrogen or oxygen during the
removal or modification of a deteriorated region of a photoresist layer on a
semiconductor substrate with a high density plasma, switching to an ashing
step in response to the monitored intensity of light emission caused by
hydrogen or oxygen, and ashing and removing the modified and/or
remaining resist in the presence of an oxygen plasma (Ans. 3-4 and 6).
According to the Examiner, the claimed step for removing a bulk of the
photoresist layer reads on Ishihara’s first step of modifying or removing the
deteriorated region on a photoresist layer (Ans. 4, 6, and 11).
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The Examiner admits that Ishihara does not teach the claimed
overetch step and the claimed hydrogen and oxygen optical emission
monitoring during Ishihara’s first step (Ans. 4-7).
To remedy these deficiencies, the Examiner relies on Tsang for
teaching the use of the claimed overetch step for removing residual resist
material and Powell for teaching the use of the claimed hydrogen and
oxygen optical emission monitoring for stopping an etching process (Ans. 4-
9). The Examiner then concludes that it would have been obvious to employ
the claimed overetch step taught by Tsang, in lieu of Ishihara’s ashing step
for removing the rest of the photoresist layer and employ the claimed
hydrogen and oxygen optical emission monitoring technique taught by
Powell, in lieu of the hydrogen or oxygen light emission intensity
monitoring used during Ishihara’s deteriorated region removal or modifying
step (Ans. 4-7). Hallock is further relied upon to explain the formation of a
harden crust layer on Ishihara’s photoresist layer (Ans. 9).
Appellants contend that the Examiner reversibly erred in finding, inter
alia, Ishihara’s first step of removing or modifying a deteriorated region on a
photoresist layer constitutes the claimed bulk removal step.
ISSUES
Have Appellants identified reversible error in the Examiner’s finding
that Ishihara’s first step of removing or modifying a deteriorated region on a
photoresist layer constitutes the claimed step for removing a bulk of the
photoresist layer?
On this record, we answer this question in the affirmative.

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FINDINGS OF FACT (“FF”)
Claim Interpretation
1. The Specification states (Spec. 6, para. 0024) that:
[O]ne chemistry or recipe can be used for
photoresist crust removal and a second chemistry
or recipe can be used for bulk photoresist removal.
Similarly, the bulk photoresist can be removed
until another emission change occurs, then a third
chemistry or recipe can be used to remove residue
that remains from the stripping process.

2. The Specification states that the crust layer is typically one to
several thousand angstroms thick and is located on top of the bulk
photoresist (Spec. 2, para. 0004).
Rejections
3. Ishihara teaches a multiple step plasma process comprising
initially modifying a deteriorated region on a photoresist layer on a
semiconductor substrate with a high density plasma (due to ion
implantation), switching to an ashing step in response to, inter alia, the
monitored light emission caused by hydrogen or oxygen, and ashing and
removing the modified resist in the presence of an oxygen plasma (pp. 6-7,
paras. 0130-0139).
4. Ishihara also teaches (p. 7, paras. 0159, 0160, 0162 and 0164)
(emphasis added) that:
[0159] If during the ion implantation the substrate
surface is inclined and the wafer is rotated, the deteriorated
region will also be formed on the side wall of the resist 27.
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[[0160] Then, the resist is modified by effecting the
plasma processing with the oxygen-, hydrogen-, and
fluorine-containing gases according to the same step as the
first step described above. The region deteriorated by the
ion implantation may be removed at the same time as this
processing or may be only modified without being removed.

[0162] Then, the process transfers to the second step to
effect the plasma processing with oxygen gas to remove the
remaining resist. . . .

[0164] According to the present embodiment, the ion
implanted resist can be removed well and rapidly without
over etching of the gate electrode or polycrystal silicon and
the film comprised of silicon oxide on the source /drain
regions.
5. Ishihara further teaches that deteriorated regions are also known
to be located on the surface of a photoresist layer (p. 1, paras. 0012 and
0013).
6. Tsang teaches (col. 7, ll. 23-32) that:
The use of the endpoint detector 59 to
monitor the light intensity associated with the
energy released by CH3* radicals returning to
ground state has provided a precise, reliable and
reproducible method of detecting the completion
of the stripping of photoresist layer 28.
After the endpoint is reached, there may be a
thin layer of residual photoresist on some areas of
polyimide layer 26. Therefore, a short, timed
overetch is employed to ensure complete removal
of photoresist layer 28. As discussed above,
several factors are believed to cause the plasma to
selectively strip the photoresist.
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7. Powell teaches monitoring the optical emissions of the plasma
at a plurality of wavelengths to determine changes in reaction by-products
produced during an etching process and stopping the etching process based
on the optical emissions of wavelengths reflective of undesired byproducts.
(pp. 4, 5, and 8, paras. 0030, 0036, 0038, 0041, and 0059).
8. Powell teaches monitoring the oxygen and hydrogen optical
emission during the semiconductor chamber cleaning and conditioning
processes (pp. 1 and 7, paras. 0014 and 0051, and Fig. 11) .
9. The Examiner relies on Hallock to teach that the implantation
of boron, phosphorus or arsenic ion causes the formation of a harden crust
layer (Ans. 9; See also Hallock, para. 0018 and Fig. 1).
PRINCIPLES OF LAW
During examination, claims terms are generally given their broadest
reasonable construction “in light of the specification as it would be
interpreted by one of ordinary skill in the art.” In re Am. Acad. of Sci. Tech.
Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004); see also In re Fout, 675 F.2d
297, 300 (CCPA 1982)(“Claims must always be read in light of the
specification. Here, the specification makes plain what appellants did and
did not invent….”). However, when the meaning of the claim term is
implied, such meaning is given. Phillips v. AWH Corp., 415 F.3d 1303,
1321 (Fed. Cir. 2005)(“[T]he specification ‘acts as a dictionary when it
expressly defines terms used in the claims or when it defines terms by
implication.”); Irdeto Access, Inc. v. Echostar Satellite Corp., 383 F.3d
1295, 1300 (Fed. Cir. 2004)(“Even when guidance is not provided in explicit
definitional format, the specification may define claim terms by implication
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such that the meaning may be found in or ascertained by a reading of the
patent documents.”). Indeed, our reviewing court stated in Phillips v. AWH
Corp., 415 F.3d at 1315:
The specification is always highly relevant to the claim
construction analysis. Usually, it is dispositive; it is the single
best guide to the meaning of a disputed term.

ANALYSIS
The multiple step plasma process recited in claims 1 and 14 requires:
removing a bulk of the photoresist layer using a bulk removal
step; and switching to an overetch step in response to the
monitored hydrogen optical emission or the monitored oxygen
optical emission.
Although the Specification does not expressly define the meaning of “a bulk
of the photoresist layer,” it provides a clear guidance as to the meaning of
such term as correctly argued by Appellants at page 6 of the Appeal Brief
and page 4 of the Reply Brief. Specifically, the Specification states (Spec. 6,
para. 0024) that:
[O]ne chemistry or recipe can be used for
photoresist crust removal and a second chemistry
or recipe can be used for bulk photoresist removal.
Similarly, the bulk photoresist can be removed
until another emission change occurs, then a third
chemistry or recipe can be used to remove residue
that remains from the stripping process.
The Specification further states at page 2, paragraph 4, that the crust layer is
typically one to several thousand angstroms thick and is located on top of the
bulk photoresist. Thus, it is clear from the Specification that the claimed
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bulk of the photoresist layer is a majority of the photoresist layer located
below a relatively thin crust (surface) layer.
Having properly interpreted the claims on appeal, we now evaluate
the propriety of the Examiner’s § 103(a) rejections. As is apparent from the
above, the Examiner’s § 103 rejections is premised upon the Examiner’s
finding that Ishihara’s first step of modifying or removing the deteriorated
region on a photoresist layer constitutes the claimed step for removing a
bulk of the photoresist layer. However, as correctly pointed out by
Appellants at page 6 of the Appeal Brief and page 4 of the Reply Brief, the
deteriorated region taught by Ishihara, like the crust layer, is located only on
the surface of a photoresist layer. Thus, it cannot be said that Ishihara’s first
step of modifying or removing the deteriorated region on a photoresist layer
constitutes the claimed step for removing a bulk of the photoresist layer.
Accordingly, even if we agree with the Examiner that the features
taught by Tsang, Powell, and Hallock are combinable in the manner
proposed by the Examiner, we determine that the combination would not
result in the claimed invention within the meaning of 35 U.S.C. § 103(a).

CONCLUSION
Appellants have identified reversible error in the Examiner’s
obviousness determination. The decision of the Examiner rejecting the
claims on appeal is reversed.
REVERSED

tc
Appeal 2009-002463
Application 11/467,842

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