Patent ID: 6768111
Filing Date: 2004-07-27
Classification: G01N

Abstract:
A method of measurement of topographic features on a surface of a substrate, comprising:a) directing a focused beam of particles to fall at a first angle &thgr;1 on to a first portion of the surface of the substrate, where &thgr;1 is defined with respect to an average normal to the surface of the substrate; b) detecting particles emitted from the first portion of the surface of the substrate at a second angle &thgr;2, where &thgr;2 is defined with respect to the average normal to the surface of the substrate, the particles detected with a particle detector; c) interposing a particle opaque material between the first portion of the surface of the substrate and the particle detector, the particle opaque material having an edge; d) determining the relative position of the edge and the first portion of the surface of the substrate from the results of the detection of particles.