| 摘要 |
<p>This invention relates to ellipsometry and reflectometry optical metrology tools that are used to evaluate semiconductor wafers, and is directed to reducing errors associated with material surrounding a desired measurement area or pad. One aspect the present invention utilizes a technique where a series of measurements are made separated by a small stage jog as the optical spot is scanned over the measurement pad. Provided the surrounding material is the same on both sides of the pad, one finds that the data invariably has either a cup or inverted 'U' shape or an inverted cup or 'U' shape when viewed as a function of position. The minimum or maximum of the curve is then used to identify the center of the pad. In another aspect of the present invention, data collected at the center of the pad is treated as being created by a superposition of light coming from the pad material itself and light coming from the surrounding material.</p> |
