This course covers advanced concepts in the patterning of photomasks or wafers by electron beam lithography. The course focuses on understanding the fundamental electron-material interaction mechanisms that form the basis of the exposure process and then proceeds to discuss the post-exposure process. This course is complementary to other courses that emphasize electron beam lithography instrumentation and writing techniques. The course is divided into six main topics: introductory material, basic electron-material interactions, applications to photomask exposure, electron proximity correction, use of simulation techniques to model the exposure process, and post exposure processing.