Effects of post-deposition treatments on ultrathin nitride/oxide gate stack prepared by RTCVD for ULSI devices

摘要

Effects of post-treatments on ultrathin nitride/oxide stacks prepared by commercial rapid thermal CVD (RTCVD) cluster tools have been investigated. Two-step post-deposition treatments (i.e., NH_3 nitridation followed by N_2O an- nealing) were performed at different temperatures to study their effects on dielectric integrity and electrical charac- teristics. And found that the gate stack can be more stoichiometric, thinner equivalent oxide thickness (EOT) and significant reduction in leakage current simultaneously by increasing NH_3 nitridation temperature. But it suffered from slightly transconductance (G_m) degradation due to incorporation of excess nitrogen. In addition, due to interfacial modification, the improved G_m can be obtained by N_2O annea1ing. However, N_2O annealing step also results in in- creasing EOT and degradation in gate current characteristics.