Electrical properties and thermal stability of MOCVD grown Ru gate electrodes for advanced CMOS technology
This paper presents an overview of electrical properties measured on advanced gate stacks consisting of a Ru electrode and Hf-based gate dielectrics. The gate stack is projected for application in the sub 45nm complementary metal-oxide-semiconductor (CMOS) technology node. Ru films were grown by metal-organic chemical vapour deposition (MOCVD) on thin HfO2, HfSiOx, HfSiON and SiO2 (control sample) dielectrics. As-deposited and forming gas annealed (90% N2+10% H2) samples were characterized by means of capacitancevoltage (CV) and conductancevoltage (GV) measurements. We discuss variation in dielectric constant, interfacial layer thickness, effective metal work function (?m,eff), oxide charge density and density of interface traps. Ru shows ?m,eff of ?5.1eV for all Ru/Hf-based dielectrics gate stacks. We also investigated the thermal stability of the stacks upon rapid thermal annealing (RTA) in the temperature range 8001000C for 10s. Samples were analyzed by Rutheford backscattering spectroscopy. The results suggest a limited thermal stability of Ru/Hf-based dielectric gate stack during source/drain activation step.
mocvd cmos rta metal gates high-? dielectrics cv measurement rbs