High-speed noninterferometric nanotopographic characterization of Si wafer surfaces

Abstract

We present a high-speed silicon wafer metrology tool capable of resolving surface features in the nanometer height range. This tool uses a high performance Shack-Hartman sensor to analyze the wavefront of a beam of light reflected from a silicon wafer surface. By translating the wafer to analyze small portions of the wafer in each camera frame and then continuously piecing the frames together, we can retain sub-millimeter spatial resolution while rapidly analyzing large apertures. This tool is particularly effective for resolving features near the wafer edge. We will describe the measures required to obtain this level of resolution. We also compare data taken with this device to that taken with the National Institute of Standards and Technology X-ray optics Calibration Interferometer (XCALIBIR). Finally, we show measurements of a variety of typical and atypical 200 mm diameter wafer samples.