Method and apparatus for evaluating internal film stress at high lateral resolution

摘要

Methods and apparatus for evaluating internal film stress on a sample at high lateral resolutions are provided. The sample comprises at least one material and has a planar or smooth surface. To determine internal stress, a calibration curve correlating a set of first ellipsometric parameter amplitudes to a set of first stress values is generated. One first stress value is correlated to one first ellipsometric amplitude. Then, the sample for which stress is to be determined is rotated as a function of sample rotation angle a and is measured for a set of second ellipsometric parameter at a selected area of the sample to determine a second ellipsometric amplitude. The internal stress at the selected area of the sample is then determined from the calibration curve by using the second ellipsometric amplitude as an index to determine a corresponding stress value from the calibration curve.