Equivalent Oxide Thickness Reduction for High-k Gate Stacks by Optimized Rare-Earth Silicate Reactions

Equivalent oxide thickness (EOT) scaling still remains one of the main facilitators to increase transistor performance. The use of rare-earth (RE) elements has been shown to effectively increase permittivity of the gate-stack interfacial layer between substrate and high- dielectric, reducing its EOT contribution. In this paper, we have studied the optimal RE-to- ratio using as a test case. Capacitance–voltage and leakage current–voltage measurements were performed on Pt-gated capacitors with a -doped gate stack and varying ratios of to after a anneal. Optimal EOT-leakage performance was found for a -to- ratio of .