Analyzing a buried layer of a sample

An inspection system for analyzing a buried layer of a sample, comprising:

• a focused ion beam (FIB) column;
• a scanning electron microscopy (SEM) column;
• and
• a computer readable medium comprising instructions that when executed cause the inspection system to perform steps comprising:
• milling a spot on the sample using a charged particle beam of the FIB column to expose the buried layer along a sidewall of the spot, wherein after the milling the sidewall of the spot is sloped;
• obtaining a first image of the sidewall of the spot using the SEM column, the first image obtained from a first perspective associated with a first angle relative to a surface of the sample;
• measuring, using the SEM column, a first distance between a first point on the sidewall corresponding to an upper surface of the buried layer and a second point on the sidewall corresponding to a lower surface of the buried layer, wherein the first distance is projected onto a horizontal plane or a vertical plane;
• obtaining a second image of the sidewall of the spot using the SEM column, the second image obtained from a second perspective associated with a second angle relative to the surface of the sample;
• measuring, using the SEM column, a second distance between the first point on the sidewall corresponding to the upper surface of the buried layer and the second point on the sidewall corresponding to the lower surface of the buried layer, wherein the second distance is projected onto the horizontal plane or the vertical plane, and the first point and the second point fall approximately on a line extending vertically through the buried layer;
• and
• determining a thickness of the buried layer using the first angle, the first distance, the second angle, and the second distance.