Phase Shift Corrections for Infrared Interference Measurement of Epitaxial Layer Thickness

Under certain conditions of wavelength and substrate impurity level, correction factors were found to be necessary for the infrared interference method of measuring epitaxial layer thickness. A general theory has been developed which relates the index of refraction and extinction coefficient to physical properties of the semiconductor and the wavelength. From these constants, a phase change at the epitaxial layer‐substrate interface is calculated. This phase shift is shown to influence the measurement and a correction factor is derived.