Metrology using differential phase contrast microscopy

By the use of simple algorithms and measurement techniques, we attempt to demonstrate the use of two differential phase contrast techniques for measurement of micron and sub-micronfeatures in several different structures representative of those used in the semiconductor industry. The technique makes use of a scanning laser interference microscope (SLIM) operating in one of two modes. The first mode uses a segmented detector placed in the Fourier plane of the microscope objective. The second mode is a differential detector scheme using a Nomarski-like optical system. Both offer the benefits of high speed video rate scanning and highly automated operation with near shot noise limited detection. © 1991.