Patent ID: 6319732
Filing Date: 2001-11-20
Classification: B24B,H01L

Abstract:
A method for controlling the temperature of a growing semitransparent layer during a production deposition process onto a major surface of a production wafer wherein heat is applied to said wafer by an intensity adjustable heat source, said production wafer emitting a broad spectrum of light during said process, said method comprising the steps of:(a) performing a test deposition process using a test wafer to create a test growing semitransparent layer, said test wafer and said test deposition process being prospectively substantially identical to said production wafer and said production deposition process;(b) forming a set of measurements over time of the intensity of light emissions from said growing semitransparent layer at a predetermined set of wavelengths;(c) using said set of measurements to determine a set of temperature values over time for said test growing semiconductor layer during said test deposition process;(d) using said temperature values and said light intensity values to compute a table relating, for a set of wavelength pairs formable from said set of wavelengths, a set of light intensity difference values to a value related to layer thickness;(e) performing said production deposition process;(f) measuring the light intensity at said set of wavelengths during said production deposition process;(g) computing production light intensity difference values for said set of wavelength pairs formable from said set of wavelengths;(h) using said production light intensity difference values and said table to determine a value related to the thickness of said semitransparent layer;(i) using said production light intensity value and said value related to layer thickness to compute an error correction value; and(j) using said error correction value to correct said intensity of said intensity adjustable heat source.