A novel method for in-line process monitoring by measuring the gray level values of SEM images

A novel semiconductor wafer metrology method for in-line process monitoring of the production wafer is proposed in this paper. A new electron beam (e-beam) system, eProfile, is developed to implement this methodology. By taking high-resolution scanning electron microscope (SEM) images on one or multiple specified locations on each die or some sampled dies and collecting gray level value (GLV) information at the locations of interest in these images, one can get the process signature across wafer very quickly. It can help to shorten the process development cycle and also can be used to monitor process in a wafer production line to prevent a process go out of specification or catch process excursions.