Sub-10-nm overlay accuracy in electron beam lithography for nanometer-scale device fabrication

A high-performance electron beam nanolithography system with an overlay accuracy of better than 10 nm has been developed and applied to nanodevice fabrication. Owing to the suppression of charge-up and precise beam position control by taking into account stage position error as well as improvements in other factors, we have obtained a stable beam (< 2 nm/5 min.), the exposure position reproducibility with stage movement (< 3 nm/500 times), and high mark-locating accuracy (3 nm). The resulting overlay accuracy is 6-9 nm in |mean| + 2σ. Using this system, we have made multi-island single-electron devices with fine gates overlaid on the Si islands within a 10-nm error. The high overlay accuracy in electron beam nanolithography will allow the study of highly functional single-electron devices.