Therma-wave, Inc.

Michael W Taylor

Allan Rosencwaig

David L Willenborg

John Schuur

The subject invention relates to a method and apparatus for identifying and testing the location of areas of interest on a workpiece and specifically, unmasked areas on a semiconductor wafer. In the subject method, the surface of the wafer is scanned with a search beam of radiation. The power of the reflected search beam will be a function of the optical reflectivity of the surface of the sample. Since the optical reflectivity of the unmasked areas are different from the masked areas, the power measurement of the reflected search beam can be used to identify the location of areas to be measured. In the preferred testing procedure, an intensity modulated pump beam is used to periodically excite a region in the identified unmasked area. A probe beam is then directed within the periodically excited region and the periodic changes in the power of the reflected probe beam, induced by the pump beam, are measured to evaluate ion dopant concentrations or the effects of processing steps, such as etching, on the surface of the wafer.

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Oakland, CA, United States of America

Michael W Taylor