Patent ID: 7295303
Filing Date: 2007-11-13
Classification: G01N,G02B

Abstract:
1. An apparatus for inspecting or imaging a semiconductor sample, comprising: an illumination lens arrangement for directing an incident beam towards a sample; an illumination aperture that include at least a first area and a second area, the first area being arranged to block a blocked spatial portion of the incident beam and the second area being arranged to transmit a transmitted spatial portion of the incident beam towards the sample; an output lens arrangement for directing an output beam from the sample towards a detector, the output beam comprising a specular portion and a scattered light portion; and a complex Fourier filter positioned within a Fourier plane of the sample, wherein the complex Fourier filter has at least a first area and a second area that vary in material composition and/or thickness, wherein the relative material compositions and thickness of the first and second area are selected so as to alter a phase of the specular portions of the output beam relative to the scattered portions of the output beam so as to enhance contrast between the scattered and specular light portions of the output beam.