Efficient and accurate optical scatterometry diagnosis of grating variation based on segmented moment matching and singular value decomposition method

To ensure the quality of the nanoimprint fabricated optical gratings, optical scatterometry (OS) is an efficient and effective mean to diagnose the actual fabricated geometry. To facilitate the diagnosis process, efficient pattern matching algorithms over a huge database are of great importance. In this paper, we present an efficient algorithm to perform the least-square pattern matching in a huge simulated spectrum database. Equipped with singular value decomposition and hierarchical moment matching algorithm, our searching and diagnosis algorithm is extremely fast and accurate. It is over 2000x faster than a plain searching algorithm with 0.1% errors.