Template-based software for accurate MEMS characterization

One of the primary challenges in MEMS metrology is the large variety of shapes, lateral feature sizes, and vertical steps on MEMS devices. This paper describes a software approach by which ideal surface templates are generated for each MEMS device from the design files or prior measurements. These templates may contain multiple sub-regions, or data islands, each of which is generally characterized in a different manner. Surface measurements from a white-light interference microscope are matched with the ideal MEMS template using a variety of techniques and threshold criteria. The template-based technique is tolerant of errors both rotation and translation, allowing accurate characterization of each data island and their relative positions. This paper will explore the concepts used to generate templates, align actual data with the original template, and sources of error and robustness of each technique on several datasets. The effect of measurement and positional errors on both the overall match and on the sub-region analyses will be explored for characterization of datasets.