Method and system for EUV mask blank buried defect analysis

摘要

A reflective mask inspection system comprises a short wavelength radiation source for irradiating a reflective mask. A detector system detects the short wavelength radiation reflected from the reflective mask and a controller compares reflectance images of the reflective mask from the detector to characterize the mask. The system analyzes the spatially resolved reflectance characteristics of the substrate from different angles with respect to normal to the substrate and/or at different angles of rotation of the substrate. This information can be used to then analyze the mask for buried defects and then characterize those defects. This technique improves over current systems that rely on atomic force microscopes, which can only provide surface information.