Wave Front Phase Imaging of Wafer Warpage

We present a new wafer metrology technique called Wave Front Phase Imaging (WFPI) for high speed measurement of wafer warpage and nanotopography. This is accomplished by acquiring a single image snapshot using that provides depth data for every single pixel. The number of topography data points for the entire wafer will be proportional to the number of pixels in the image sensor. Sub nanometer depth resolution is achieved by using 2 cameras with optics that image the entire wafer, with the exact same field of view, at different conjugation planes. Monochromatic uncoherent light is illuminating the wafer and lateral resolution is determined by the lenses used for a specific field of view and the number of pixels offered by the image sensor.