Ex Parte 5963329 et al

Board of Patent Appeals and Interferences

Apr 25, 2006

90006185 (B.P.A.I. Apr. 25, 2006)

THIS OPINION WAS NOT WRITTEN FOR PUBLICATION

The opinion in support of the decision entered today (1) was not written for
publication in a law journal and (2) is not binding precedent of the Board.

UNITED STATES PATENT AND TRADEMARK OFFICE
__________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________________

Ex parte EDWARD W. CONRAD
and DAVID P. PAUL

Appeal No. 2006-0741
Reexamination Control No. 90/006,185
Patent No. 5,963,3291

HEARD April 5, 2006

Before MARTIN, LEE and MOORE, Administrative Patent Judges.

LEE, Administrative Patent Judge.

DECISION ON APPEAL

This is a decision on appeal under 35 U.S.C. § 134 and § 306 from the
examiner’s rejection of the patentee’s claims 1-14 and 16-28 in the patent
reexamination proceeding.
References relied on by the Examiner
Raymond et al. (Raymond) “Metrology of subwavelength photoresist gratings using
optical scatterometry,” Journal of Vacuum Science &
Technology, B, Vol. 13, No. 4, July/August 1995, pp. 1484-
1495

1 Issued October 5, 1999, and based on application 08/961,929, filed October 31, 1997.
Request for reexamination received January 10, 2002. The real party in interest is Nanometrics Incorporated.
Moharam et al. (Moharam) “Diffraction characteristics of photoresist surface-relief
gratings,” Applied Optics, Vol. 23, No. 18 (September 15,
1984), pp. 3214-3220.
Case et al. (Case) 4,555,767 November 1985

Lochbihler et al. (Lochbihler I) “Characterization of highly conducting wire gratings
using an electromagnetic theory of diffraction,” Optics
Communications, Vol. 100, 1993, pp. 231-239.

Lochbihler et al. (Lochbihler II) “Characterization of x-ray transmission gratings,”
Applied Optics, Vol. 31, No. 7 (March 01, 1992), pp.
964-971.

The Rejections on Appeal

Claims 1-4, 8-13, 16, 17, 20, and 27-28 stand rejected under 35 U.S.C. § 103 as
being unpatentable over Raymond and Moharam.
Claims 5-7, 14, 18-19, and 21-26 stand rejected under 35 U.S.C. § 103 as being
unpatentable over Raymond, Moharam, Case, Lochbihler I, and Lochbihler II.
The Invention
The invention is directed to a method and apparatus for determining the profile
on a substrate having repeating structure by use of actual radiation diffraction and
mathematical modeling. The intensity of diffracted illumination is compared with the
predicted intensity of a model based on mathematical calculations. The independent
claims are claims 1, 27 and 28, each of which is reproduced below:
1. A method of determining a profile, comprising the steps of:

(a) providing a substrate having a repeating structure
comprising a plurality of lines, said lines having substantially
identical profiles;

(b) illuminating said repeating structure with radiation
wherein said radiation diffracts, said diffracted radiation
having an intensity as a function of wavelength;

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Reexamination Control No. 90/006,185

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(c) measuring said intensity as a function of
wavelength;

(d) providing a model structure on a data processing
machine, said model structure comprising a repeating
structure on said substrate, said model structure comprising
a model profile, wherein said model profile comprises an
edge having more than one X position;

(e) mathematically predicting a predicted diffracted
radiation intensity when said model structure is illuminated
with said radiation; and

(f) comparing said predicted intensity with said
measured intensity.

27. A method of determining the profile of a repeating structure
comprising the steps of:

(a) providing a substrate having a plurality of lines
having substantially identical line profiles and spacings;

(b) illuminating said lines with radiation having a range
of wavelengths, wherein said radiation reflects with an
intensity as a function of wavelength;

(c) selecting a polarization state of said reflected
radiation;

(d) measuring the intensity of radiation reflected from
said lines as a function of wavelength;

(e) providing a model of the line profile and line
spacing, wherein said model of the line profile comprises an
edge having more than one X position;

(f) mathematically predicting the intensity of radiation
that would be reflected from the model as a function of
wavelength; and
(g) comparing the predicted intensity with the
measured intensity; and

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(h) adjusting the model and repeating steps (f) and (g)
to improve agreement in said comparing step (g).

28. An apparatus for determining the profile of a line on a substrate, the
apparatus comprising:

a radiation source for illuminating the substrate with
radiation, said substrate comprising a repeating structure,
said repeating structure comprising a plurality of lines and
spaces between said lines, said lines having substantially
the same line profile, said spaces being substantially
identical, the illuminating of the repeating structure for
obtaining diffraction of said radiation, wherein said diffracted
radiation has an intensity as a function of wavelength;

a polarizer for selecting a single polarization state of
diffracted light;

a detector for measuring said intensity as a function of
wavelength;

a data processing machine comprising a computer
model structure, said model structure comprising a model
repeating structure on a model substrate, said repeating
structure comprising a plurality of model lines and model
spaces between said model lines, said model lines having
substantially the same model line profile, each said model
line comprising an edge having more than one X position,
said model spaces being substantially identical, said data
processing machine for mathematically predicting a
predicted diffracted radiation intensity when said model
structure is illuminated with said radiation source;

said data processing machine further comprising
means for comparing said predicted intensity with said
measured intensity; and

said data processing machine further comprising
means for adjusting said model structure and for repeating
said predicting and comparing steps to improve agreement
in said comparing step.
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Discussion
A. The rejection of claims 1-4, 8-13, 16, 17, 20 and
27-28 under 35 U.S.C. § 103 over Raymond and Moharam

The examiner applied Raymond as a primary reference disclosing the measuring of actual
diffracted illumination from a substrate with repeating structures and a theoretical prediction of
anticipated diffraction based on a mathematical algorithm. In Raymond, first the actual
diffracted light fingerprint is measured (page 1485, column 2, lines 19-21 and 26-27).
Thereafter, a diffraction model is used while varying each parameter over a certain range to
calculate the theoretical diffraction over a parameter space (page 1485, column 2, lines 29-35).
Based on the prediction data, those parameters that correspond to the actual diffraction
fingerprint are determined (page 1485, column 2, lines 36-38).
The appellant argues that the invention according to claim 1 applies broadband light as
the source of illumination for the substrate (Brief at 2). The appellant argues that according to
claim 27 the source of illumination has a range of wavelengths (Brief at 2). The appellant argues
that according to all three independent claims 1, 27 and 28, the diffracted or reflected radiation
has an intensity which is a function of wavelength and the diffracted or reflected radiation is
measured as a function of wavelength (Brief at 2-3). The appellant states that Raymond does not
teach applying a source radiation which has a range of wavelengths, or having any diffracted
radiation which has an intensity as a function of wavelength, or measuring the diffracted
radiation as a function of wavelength (Brief at 5).
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At oral hearing the panel pointed out to counsel for the appellant that none of the three
independent claims recites broadband illumination and that only claim 27 recites that the source
illumination has a range of wavelengths, which may be construed as broadband illumination.
The response from counsel for the appellant was that appellant’s claims 1 and 28 likewise
require the source of illumination to have a range of wavelengths, and thus broadband
illumination, because claims 1 and 28 recite that the applied illumination diffracts or reflects
with an intensity that is a function of wavelength and that the diffracted illumination is measured
as a function of wavelength. We agree. In light of the claim language to the effect that the
diffracted or reflected radiation has an intensity which is a function of wavelength and that the
diffracted or reflected radiation is measured as a function of wavelength, the claims are properly
interpreted as requiring source illumination which has a range of wavelengths. If not, then the
diffracted or reflected radiation could not reasonably be deemed as “measured as a function of
wavelength.”2 There is no dispute between the examiner and the appellant in that regard. Single
wavelength source illumination such as the laser light of Raymond is not sufficient for meeting

2 We recognize that claim 12 depends ultimately from claim 1 and further requires that
the radiation has a range of wavelengths, which additional requirement is an indication that
claim 1 does not by itself require the radiation to have a range of wavelengths per application of
the doctrine of claim differentiation. However, the doctrine is not a controlling factor for claim
interpretation. Here, the language of claim 1 compels a conclusion otherwise.
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the appellant’s claims. The examiner recognized that, and attempted to make up the deficiency
of Raymond by relying on disclosure of the Moharam reference.
But the examiner’s reliance on Moharam is misplaced. According to the examiner,
Moharam discloses that diffraction intensity is measured as a function of wavelength, employs a
similar rigorous coupled wave analysis and is within the same field of endeavor as Raymond
(Answer at 5, lines 4-10). As is correctly noted by the appellant, however, that part of Moharam
evidently relied on by the examiner states (Moharam, p. 3219, column 2, lines 13-17):
The diffraction characteristics as a function of (1) angle of incidence, (2)
polarization, and (3) wavelength have all been measured experimentally and
calculated theoretically using a surface-relief modulated half-space model. Good
general agreement is found between theory and experiment.

That disclosure, however, reveals only that diffraction characteristics depend on the angle of
incidence of the source illumination, on the polarization of the source illumination, and on the
wavelength of the source illumination. As is stated in the introduction portion of Moharam
(page 3214, column 2, lines 3-9):
This study compares theoretically calculated and experimentally measured
angular selectivities (angle of incidence dependence of the diffraction efficiency
at a fixed wavelength) and wavelength selectivities (wavelength dependence of
the diffraction efficiency for a fixed angle of incidence) of these gratings for both
TE and TM polarizations.

The Moharam reference studies how diffraction results change based on variations in the angle
of incidence while the wavelength is fixed, and on variations in the wavelength of the source
illumination while the angle of incidence is fixed, for both TE and TM polarizations of the
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incident light. Angular and wavelength selectivities are determined. As is described in
Moharam on page 3217, column 2, lines 4-8:
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The angular and wavelength selectivities of a grating are measures of the
sensitivity of the diffraction to changes in the angle of incidence (with the
wavelength fixed) and to changes in the wavelength (with the angle of incidence
fixed).

Moharam discloses the use of a source illumination including a range of wavelengths and the
measuring of diffraction intensity as a function of wavelength. But it is for determining
diffraction sensitivities to differences in the wavelength of the source illumination, and not a
blanket teaching that source illumination having a range of wavelengths be applied and
diffraction intensity be measured as a function of wavelength whenever diffraction of source
illumination from a substrate is measured.
Moreover, as is pointed out by the appellant, in Moharam while the angle of incidence is
varied, the wavelength of the incident illumination remains fixed, and while the wavelength of
the incident illumination is varied, the angle of incidence remains fixed (Moharam, page 3214,
column 2, lines 3-9; page 3217, column 2, lines 4-8). Moharam teaches that the intensity of the
diffracted radiation depends on the wavelength of the source illumination and not that source
illumination including a range of wavelengths should be applied and that the resulting diffraction
should be measured as a function of wavelength in any particular type of situation other than for
measuring diffraction efficiencies.
The foregoing is consistent with the following paragraph contained in the declaration of
Mircea Dusa submitted by the appellant on July 21, 2003, and attached to the appellant’s brief:
8. Moharam relates to the examination of diffraction characteristics of
photoresist diffraction gratings. Moharam studies the angular and
wavelength selectivities of diffraction gratings by measuring the
sensitivity of the diffraction to changes in the angle of incidence (with the
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wavelength fixed) and to changes in the wavelength (with the angle of
incidence fixed). See, p. 3217, second column, 1st full paragraph, and see
Abstract. Moharam also studies the sensitivity of the diffraction gratings
to the polarization (TE or TM) of the incident light. See, p. 3217,
paragraph bridging 1st and 2nd columns.

The examiner has articulated no basis to discredit the above-quoted testimony of Mircea Dusa.
Raymond discloses a system and method for determining the widths and overall profiles
of dielectric grating lines by measuring the intensity of diffracted laser light from the sample
substrate over a specified range of incident beam angles (Raymond, page 1484, Introduction).
As is determined correctly by the examiner (Answer at 4), Raymond discloses comparing the
predicted diffraction intensity over the range of incident beam angles as calculated through a
mathematical algorithm applied to a model to the actual measured diffraction intensity
(Raymond, page 1485, column 2, lines 9-49). But the wavelength of incident illumination is
fixed and the diffraction intensity is not measured as a function of wavelength. Raymond’s
system and method depend on measuring the diffraction intensity as a function of a varying
incident angle. As is stated in Raymond on page 1485, column 2, lines 46-54:
The sample is mounted on a stage that permits it to rotate. Since the beam itself is
fixed, this rotation changes the angle of incidence on the sample. Using grating
Eq. (1), the detector arm of the scatterometer is able to follow any diffracted order
as this angle is varied. The intensity of a particular diffraction order as a function
of incident angle, which is known as 2-t plot or scatter “signature,” is then
downloaded to a computer, where the analysis can begin.

The wavelength of Raymond’s incident laser is not changed when the incident angle is changed.
Similarly, in Moharam, as is discussed above, while the angle of incidence is changed, the
wavelength of the source illumination stays fixed.
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Obviousness is a question of law based on findings of underlying facts relating to the
prior art, the skill of the artisan, and objective considerations. See Graham v. John Deere Co.,
383 U.S. 1, 17, 148 USPQ 459, 467 (1966). To establish a prima facie case of obviousness
based on a combination of the content of multiple references, there must be a teaching,
suggestion, or motivation in the prior art to make the specific combination that was made by the
applicant. In re Raynes, 7 F.3d 1037, 1039, 28 USPQ2d 1630, 1631 (Fed. Cir. 1993); In re
Oetiker, 977 F.2d 1443, 1445, 24 USPQ2d 1443, 1445 (Fed. Cir. 1992). As discussed in
Interconnect Planning Corp. v. Feil, 774 F.2d 1132, 1143, 227 USPQ 543, 551 (Fed. Cir. 1985),
it is the prior art itself, and not the applicant's disclosure, that must establish the obviousness of
the combination.
The examiner has not articulated any reasonable teaching, suggestion, or
motivation for one with ordinary skill in the art, in light of the Moharam reference, to
apply in Raymond source illumination including a range of wavelengths and then
measuring the diffracted or reflected illumination as a function of wavelength. The
rigorous diffraction model and the statistical prediction algorithm used in Raymond are
based on varying the incident angle with a fixed wavelength and not the inverse, i.e.,
multiple wavelength of incident illumination and a fixed incident angle. Also, Moharam
does not disclose the application of incident illumination with multiple wavelengths and
measuring the resulting diffraction as a function of wavelength in any particular
application except for determining the sensitivity of diffraction to wavelength, and even
then, it would be for a fixed incident angle of illumination. Based on the disclosure of
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Raymond and Moharam, as presented by the examiner, we do not see how one with
ordinary skill in the art would recognize that something useful or beneficial would result
by applying source illumination with a range of wavelengths in Raymond and measuring
the resulting diffraction as a function of wavelength. That rationale has not been
adequately established by the examiner.
We do not disagree that for determining the selectivity of diffracted radiation to
the wavelength of the incident light, Moharam discloses applying, with a fixed incident
angle, source illumination including a range of wavelengths and thereafter measuring
the resulting diffraction as a function of wavelength. However, that disclosure is a long
way from being a reasonable teaching, suggestion, or motivation for applying in
Raymond a source illumination which includes a range of wavelengths and measuring in
Raymond the resulting diffraction as a function of wavelength. Raymond’s system and
method depend on a varying incident angle and a fixed wavelength for its source
illumination.
Claim 27 further requires the step of selecting a polarization state of the reflected
radiation. Claim 28 further recites a polarizer for selecting a single polarization state of
diffracted light. The examiner attempted to meet these requirements by relying on
Raymond’s disclosure that TE polarized laser is used as the source illumination and on
Moharam’s disclosure that changes in diffraction efficiency based on incident angle and
wavelength of the source illumination are more acute for incident light with TE
polarization than incident light with TM polarization (Answer at 10-11). The comparison
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is inappropriate and inadequately explained because the polarization referred to in
Raymond and in Moharam is with regard to the incident illumination. The examiner has
not shown that either reference teaches selecting a polarization state of the reflected
radiation as is recited in claim 27 or a polarizer for selecting a single polarization state of
diffracted light as is recited in claim 28.
For all of the foregoing reasons, the rejection of claims 1-4, 8-13, 16, 17, 20, and
27-28 over Raymond and Moharam cannot be sustained. We have no need to consider
objective evidence of nonobviousness submitted by the appellant with regard to alleged
commercial success.
B. The rejection of claims 5-7, 14, 18-19, and 21-26 under 35 U.S.C. § 103
as unpatentable over Raymond, Moharam, Case, Lochbihler I, and Lochbihler II

As applied by the examiner, the deficiencies of Raymond and Moharam is not
made up by the disclosure of Case, Lochbihler I, and Lochbihler II. Accordingly, the
rejection of dependent claims 5-7, 14, 18-19, and 21-26 also cannot be sustained.
Conclusion
The rejection of claims 1-4, 8-13, 16, 17, 20, and 27-28 under 35 U.S.C. § 103 as
unpatentable over Raymond and Moharam is reversed.
The rejection of claims 5-7, 14, 18-19, and 21-26 under 35 U.S.C. § 103 as
unpatentable over Raymond, Moharam, Case, Lochbihler I and Lochbihler II is
reversed.
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REVERSED

/John Martin/ )
JOHN MARTIN )
Administrative Patent Judge )
)
)
)
/Jameson Lee/ ) BOARD OF PATENT
JAMESON LEE ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
/James T. Moore/ )
JAMES T. MOORE )
Administrative Patent Judge )

Appeal No. 2006-0741
Reexamination Control No. 90/006,185

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By First Class Mail

Attorney for the appellant:

Michael J. Halbert
Silicon Valley Patent Group LLP
2350 Mission College Boulevard.
Suite 360
Santa Clara, California 95054