发明授权
US08239163B2 Apparatus for and a method of determining surface characteristics 失效
用于确定表面特性的装置和方法

Apparatus for and a method of determining surface characteristics
摘要:
A coherence scanning interferometer carries out: a coherence scanning measurement operation on a surface area using a low numeric aperture objective so that the pitch of the surface structure elements is less that the spread of the point spread function at the surface to obtain structure surface intensity data; and a coherence scanning measurement operation on a non-structure surface area to obtain non-structure surface intensity data. A frequency transform ratio determiner determines a frequency transform ratio related to the ratio between the structure surface intensity data and the non-structure surface intensity data. A structure provider sets that frequency transform ratio equal to an expression representing the electric field at the image plane of the interferometer in terms of surface structure element size (height or depth) and width-to-pitch ratio and derives the surface structure element size and width-to-pitch ratio using the frequency transform ratio.
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