イオン注入中のウェハ帯電現象の解析

Abstract

Charge-up phenomena during ion implantation were studied using the wafers (1) covered with the 1μm thick photoresist and (2) fabricated with the MOS capacitor devices. The wafers were implanted with 35keV As+ at the beam currents of 1mA to 10mA. The surface potential was measured by a capacitive probe set in the chamber. The ion distribution was also measured by a beam profile monitor placed behind the rotating disc. Surface charging on the photoresist wafers in some cases led to the puncture of the resist layer. Probe measurement showed that the charge-up phenomena were to a large extent governed by the behavior of the secondary electrons generated at ion implantation. The wafers with the MOS devices hardly failed by the charge build-up because of the bulk conduction through the thin oxide. However, the C-V measurement indicated that the deterioration of the oxide are influenced by the beam distribution.