Electron-beam direct writing technology for fine gate patterning

Abstract

Electron beam (EB) lithography along with photo lithography is a good candidate for fabricating fine patterns smaller than 200 nm. We examined the pattern fidelity which was one of the most important points for applying EB lithography for proto-typing ULSIs. We used a direct writing EB system with a shaped beam. In this paper, we applied EB direct writing for the gate fabrication of 250-nm CMOS devices. The fidelity in resist patterns was 55 nm. The deviation was 21 nm, and the variation was +/- 17 nm. We also applied EB/DW and i-line exposure for the gate fabrication of 350-nm CMOS devices, and measured the source-drain current in nMOS transistors. We compared the Lg fluctuations which were calculated by Ids fluctuations. The magnitude of the fluctuations around Lg- equals 350 nm with EB/DW was less than half of that with i-line. According to these result, EB lithography is very effective for fabricating very fine gates of ULSIs.