Measuring semiconductor device features using stepwise optical metrology

摘要

The present invention relates generally to metrology, and more particularly, to an apparatus and method of measuring multiple parameters of a structure or feature of a semiconductor device using a combination of stepwise optical metrology and a linear system of equations to generate an output as function of position. In an embodiment, a light beam having a width greater than the features to be measured may be shined on a first area of the semiconductor device to calculate a first average. The light beam may then be shined on a second area that overlaps the first area by at least one individual feature to calculate a second average. The averages may be entered into a system of linear equations which may then be solved to calculate an overall average.

主权项

1. A method of measuring an average characteristic of features on a semiconductor structure comprising:
projecting a light beam onto the features in a first area; collecting a first reflected light beam from the first area, wherein the first reflected light beam is the projected light beam after it has reflected off the features in the first area; converting the first reflected light beam into first data; projecting the light beam onto the features in a second area, wherein the second area overlaps with the first area by at least one individual feature; collecting a second reflected light beam from the second area, wherein the second reflected light beam is the projected light beam after it has reflected off the features in the second area; converting the second reflected light beam into second data; performing analysis of the first data and second data to determine an overall average value; comparing the overall average value to a predetermined desired value; and discarding the semiconductor structure if the overall value differs from the desired value by a predetermined amount.