Method and apparatus for thickness decomposition of...

Details Method and apparatus for thickness decomposition of... Method and apparatus for thickness decomposition of...

2005-04-26

2005-04-26

Toatley, Jr., Gregory J. (Department: 2877)

Optics: measuring and testing

Dimension

Thickness

C250S461100

Reexamination Certificate

active

06885467

ABSTRACT:
Thickness measurement apparatus for measuring layer thicknesses on patterned areas of a semiconductor wafer, comprises: a spectrum analyzer for obtaining reflection data taken from a patterned area and obtaining therefrom a frequency spectrum, a peak detector for searching the spectrum to find peak frequencies within said spectrum, the search being restricted to regions corresponding to peak frequencies found in an earlier learning stage, a frequency filter, associated with the peak detector, for filtering the spectrum about said peak frequencies, and a maximum likelihood fitter for using parameters obtained in the learning stage to carry out maximum likelihood fitting of said filtered spectrum to obtain the desired layer thicknesses. By carrying out maximum likelihood fitting using parameters obtained beforehand in a high resolution non-real time learning stage, it is possible to provide high resolution results in real time.

REFERENCES:
patent: 4841156 (1989-06-01), May et al.
patent: 5227861 (1993-07-01), Nishizawa et al.
patent: 5450205 (1995-09-01), Sawin et al.
patent: 5773316 (1998-06-01), Kurosaki et al.
patent: 6268916 (2001-07-01), Lee et al.
patent: WO 0012958 (2000-03-01), None

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