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To meet the gate leakage specifications in the International Technology Roadmap for Semiconductors (ITRS), an intensive search is being conducted for alternative gate stack materials. Most of the studies have focused on basic material properties, but very little effort has been directed towards quantifying and understanding the effect of post metallization annealing (PMA) on the electrical properties of the dielectric. In this work, devices were fabricated with a "gate last" process. The gate dielectrics studied included: HfO 2 deposited by PVD or MOCVD, as well as Y 2 O 3 and La 2 O 3 deposited by RPECVD and MBE, respectively. Poly-Si gate electrodes were prepared by 600°C LPCVD followed by ion implantation and dopant activation using 900°C 60sec RTA. Device characteristics were measured before and after 20 min 400-450°C forming gas (FG, 10% H 2 Here the mobility parameters, including EOT, were extracted from device I-V data based on the assumptions that: a) EOT was not affected by PMA and b) the post-PMA scattering parameters were the same as good SiO 2 (3e10/cm 2 ). Peak mobility of 63% and 57% higher were observed for La 2 O 3 and Y 2 O 3 , respectively. Dramatic reductions in interface scattering charges were observed: from 19 and 11 e10/cm 2 for Y 2 O 3 and La 2 O 3 respectively, to 3e10/cm 2 . The roughness scattering parameters did not change much. It seems that the FG post metallization annealing reduces interface charge also for group III materials. The gate leakage was not affected by PMA for either material.

The stability of poly-Si gated HfO 2 ͑ϳ1.2 nm equivalent oxide thickness, EOT͒ and Y 2 O 3 ͑ϳ3.1 nm EOT͒ n-channel metal oxide semiconductor field effect transistor devices were assessed after constant current stressing of the gate. The changes in threshold voltage and transconductance were measured as a function of stress time and stress current over the range of 10 Ϫ3 to 10 5 C of injected charge per square centimeter. With forming gas annealed HfO 2 , positive shifts in the threshold voltage exhibited a powerlaw dependence. Under high stressing conditions, a power-law dependence of degradation of threshold voltage on the injected charge (ϳQ 0.1 ) was observed. Stressing at high current was seen to generate traps. Stressing at low current revealed a saturation of the threshold voltage after modest stressing times. Stressing on deuterium annealed sample showed less V t and g m shift ͑under high injection conditions͒, which is attributed to the effectiveness of heavier D 2 in preventing trap generation under high stressing conditions. With Y 2 O 3 , stressed at similar electric fields, the threshold voltage shifted negatively and the transconductance increased.