Methods of cross-section imaging of an inspection volume in a wafer

A method, comprising:

• alternately imaging and milling into an inspection volume of a wafer at a slant angle to obtain a sequence of N cross-section surfaces of the wafer and a corresponding sequence of N cross-section image slices of the wafer;
• determining a first orientation direction of first semiconductor features of the wafer, the first semiconductor features forming a first plurality of first cross-section image features in the sequence of N cross-section image slices of the wafer;
• and
• computing a virtual cross-section image perpendicular to the first orientation direction, the virtual cross-section image comprising a plurality of virtual cross-section image pixels,
• wherein, for each virtual cross-section image pixel, the method comprises:
• computing a pixel value by projecting a subset of at least one cross-section image slice of the sequence of N cross-section image slices in the first orientation direction;
• selecting the subset of the at least one cross-section image slice by evaluating a distance of each of the sequence of N cross-section image slices to the virtual cross-section image pixel in the first orientation direction;
• and
• selecting a first cross-section image slice having the shortest distance to the virtual cross-section image pixel in the first orientation direction.