First Results Of A Product Utilizing Coherence Probe Imaging For Wafer Inspection

Abstract

A description of a new product, the first to utilize Coherence Probe Imaging, is given, and application results are presented. In Coherence Probe Imaging, data from an interference microscope is transformed by means of a nonlinear transformation implemented electronically to produce three dimensional images of higher resolution than an ordinary microscope. Because of the parallel nature of the image acquisition, conventional light sources can be used for illumination. Critical dimension or linewidth data analysis is presented. Comparisons to scanning electron microscope measurement are made. Typical linewidth reports are shown. Illustrative reports from the layer to layer misregistration measurement function of the machine is also shown. The coherence probe technique is used to make extended depth of focus pictures and z maps showing topographical detail. Sample images showing these features are shown. Automation features of the machine are also described, such as the automatic wafer alignment system on the machine and the random access robotic wafer handling system.