| 摘要 |
<p>A method for optically inspecting and evaluating a semiconductor wafer includes projecting a probe beam at two overlay targets. Each overlay target includes an upper grating and a lower grating. At each target, the combined intensity of the 1<St> diffracted orders generated by the upper and lower gratings are measured. The combined intensity of the -1<St> diffracted orders generated by the upper and lower gratings are also measured for each target. The method then calculates an overlay offset between an upper layer and a lower layer as a function of the measured intensity information.</p> |
