METHOD AND APPARATUS FOR MEASURING CRITICAL DIMENSIONS WITH A PARTICLE BEAM

摘要

A method and system for determining a cross sectional feature of a structural element having a sub-micron cross section, the cross section is defined by an intermediate section that is located between a first and a second traverse sections. The method includes: (a) determining a first traverse section cross sectional feature in response to one or more scans of the structural element with an electron beam that is tilted at one or more corresponding tilt angle, such as to illuminate at least the top section and a first transverse section; (b) selecting, in response to a first parameter, whether to (i) determine a second traverse section cross sectional feature in response to the first traverse cross sectional feature, or (ii) to determine the second traverse section cross sectional feature in response to one or more scans of the structural element with an electron beam that is tilted at one or more corresponding tilt angle, such as to illuminate at least the top section and the second transverse section; and (c) determining the second traverse section cross sectional feature in response to the selection.