Optical volumetric inspection of sub-20nm patterned defects with wafer noise

Abstract

We have previously introduced a new data analysis method that more thoroughly utilizes scattered optical intensity data collected during defect inspection using bright-field microscopy. This volumetric approach allows conversion of focusresolved 2-D collected images into 3-D volumes of intensity information and also permits the use of multi-dimensional processing and thresholding techniques to enhance defect detectability. In this paper, the effects of wafer noise upon detectability using volumetric processing are assessed with both simulations and experiments using the SEMATECH 9 nm node intentional defect array. The potential extensibility and industrial application of this technique are evaluated.

Through-focus or volumetric type of optical imaging methods: a review

“…However, with the development of technology, improved optical simulations and new insights it was found that the out-of-focus TF images do contain useful information regarding the target being imaged. New applications and uses are being found for blurred optical images that were previously considered unusable (20, 29, 32, 34, 43–48). The major challenge was to extract high quality, usable information from the blurred TF optical images.…”