Patent ID: 8639377

Claim:
A method, comprising: receiving a semiconductor substrate having a layer of GST, the layer of GST having a thickness and a structural phase; exposing the layer of GST to an incident non-polarized light having an infra-red component; measuring a transmittance intensity of the infra-red component through the layer of GST and substrate; and determining the thickness of the layer of GST for the structural phase, based on the measured transmittance intensity and a plurality of predetermined correlations between a plurality of transmittance intensities of the infra-red component through a layer of GST and a plurality of thicknesses at a plurality of structural phases of GST, wherein determining the thickness comprises determining the structural phase of the layer of GST based on a plurality of predetermined correlations between a plurality of transmittance intensities of the infra-red component through a layer of GST at a plurality of structural phases of GST; and storing the determined thickness in a computer readable medium.