Rapid thermal post-metallization annealing in thin gate oxides

Rapid thermal technique was used in the post-metallization annealing (PMA) of thin gate oxide devices. A suitable choice of the rise rate, the setting temperature, and the hold time in the rapid thermal PMA (RTPMA) process is helpful to improve the oxide quality. It was found that the samples subjected to appropriate RTPMA conditions exhibit almost the same initial characteristic in flatband voltage V-FB and midgap interface trap density D-itm as those subjected to conventional furnace PMA (FPMA). However, the RTPMA samples exhibit longer time-to-breakdown t(HD) and higher time-zero-dielectric-breakdown (TZDB) field E(BD) than the FPMA ones. In addition to the known spiking effect caused by aluminum penetration into silicon, which seriously degrades the breakdown property, formation of aluminum oxide near the Al/SiO2 interface in the early stage and then aluminum silicon alloy in the later stage was proposed to explain the experimental observation.