Patent ID: 7438468

Claim:
A method of heating a wafer of a semiconductor material, comprising: generating laser radiation of a laser wavelength that is absorbed as heat by the semiconductor material; filtering from said laser radiation a pyrometer wavelength band at which said semiconductor material emits blackbody radiation when heated by said laser radiation; passing said laser radiation through a beam splitter reflective at said laser wavelength and transmissive at said pyrometer wavelength band; focusing the laser radiation reflected by the beam splitter to a line beam having a narrow width that is a fraction of a diameter of the wafer; heating a constantly moving narrow surface zone of said wafer corresponding to said narrow line beam width to a selected temperature on the order of 1000 degrees C. for a time duration by scanning said line beam across a surface of the wafer at a selected scan rate that is sufficient to limit said time duration and limit a depth of said surface zone; imaging the moving zone of the wafer surface illuminated by the line beam onto the beam splitter to provide a beam of wafer radiation emanating from the moving surface zone of the wafer; and passing the portion of said wafer radiation lying within said pyrometer wavelength band through said beam splitter to an optical detector responsive within said pyrometer wavelength band.