New Flash Lamp Annealing Tool Equipped with an Ambient Control Feature Suitable for High-k Gate Stack Anneals

A new millisecond, flash lamp annealing (FLA) tool has been developed. Building on the current tool's wide range of annealing times and temperatures, the new FLA tool is equipped with an ambient control system that can establish a reduced pressure and/or an NH3 reactive-gas ambient. These features have an advantage in gate stack anneals compared to conventional second order annealing: FLA prevents deactivation of dopants in gate-last processes, further densifies the HfO2 layer and the IL, and enables nitridation of the HfO2 layer while avoiding N diffusion to the Si substrate. Moreover, the electrical properties using MOSCAPs processed by FLA show prominent improvements in the EOT and gate leakage current. A positive Vfb shift is also observed in MOSCAPs using FLA. These results show that FLA using NH3 is a promising process for sub 10nm generation gate stack anneals.