Impact of recoiled-oxygen-free processing on 1.5 nm SiONgate-dielectric in sub-100 nm CMOS technology

摘要

We have developed high-quality 1.5 nm SiON gate dielectrics usingrecoiled-oxygen-free processing. We found that oxygen recoiling from asacrificial oxide during ion implantation or defects induced by recoiledoxygen change the growth mechanism of SiON gate dielectrics of less than2 nm and degrade the controllability of film thickness, film quality,and device electrical characteristics. PMOSFETs using therecoiled-oxygen-free process and As-implantation for the channel havebetter controllability of gate dielectric thickness, up to one-thirdless gate leakage current, a hundred times more reliable TDDBcharacteristics, and a 20% improvement in drain current compared to theconventional process. Thus, a Si substrate without recoiled oxygen isessential in forming high-quality SiON gate dielectrics of less than 1.5nm