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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