Patent ID: 6010914
Filing Date: 2000-01-04
Classification: H01L

Abstract:
A method for manufacturing a semiconductor device comprising the steps of:(a) disposing a test pattern area on a silicon wafer outside a product area of said silicon wafer,(b) forming a first layer on said test pattern area having a layer of material with a different refractive index from that of Si;(c) forming a first poly Si layer on top of said first layer on said test pattern area;(d) forming an epitaxial layer in said product area and simultaneously forming a second poly Si layer on said first poly Si layer in said test pattern area,(e) measuring a thickness of one of (i) the first poly Si layer and (ii) the total thickness of said first poly Si layer and the second poly Si layer using visible light optical interference techniques; and(f) determining from the measuring step the thickness of said second poly Si layer; and(g) determining from said second poly Si layer the thickness of the simultaneously formed epitaxial layer.