Patent ID: 9389408
Filing Date: 2016-07-12
CPC Classification: G01N,G02B,G06T

Claim Text:
1. A method of measuring a patterned substrate sample, the patterned substrate sample including a plurality of patterned substrate features, the method comprising: varying a relative distance between the patterned substrate sample and an objective lens at predetermined steps; at one or more of the predetermined steps: roughly determining a Z position of a background area of the patterned substrate sample using the second image array, and generating a first mask to roughly distinguish the patterned substrate features from the background area of the patterned substrate sample based on the roughly determined Z position; generating a second mask to accurately distinguish the patterned substrate features from the background area based on the first image array and the first mask; determining a top of each patterned substrate feature using the second mask and one of the first image array and the second image array; and calculating geometric parameters of patterned substrate features using the second mask and the top of each patterned substrate feature.