Measuring Thickness of Epitaxial Layer
Original Publication Date: 1985-Jul-01
Included in the Prior Art Database: 2005-Feb-18
In the processing of a semi-conductor wafer, it is common to measure the thickness of an epitaxial (epi) layer grown thereon, at several different points. Such measurements can be done on a Fourier transform infrared (FTIR) spectrometer by a method which involves using a Fourier transform at a first measurement point to accurately determine the thickness, and thereafter using an interferogram directly, without any FT, to determine the thickness at another point on the wafer. Fig. 1 shows an FTIR spectrometer in which a wafer 1 is irradiated with IR energy from a source 2.