Highly accurate alignment technology for electron-beam lithography in mix-and-match with optical stepper

A novel alignment technology for electron-beam lithography is proposed for hybrid use with i-line steppers. This alignment technology was developed based on the evaluation of alignment characteristics and on the investigation of alignment errors in electron-beam lithography systems used in the mix-and-match process. In this alignment method, global alignment using representative chips on a wafer effectively achieves accurate overlay and high throughput. Overlay measurements showed that the deviation in the alignment error is smaller than 70 nm within 3σ.