Formation and characterization of tin layers for metal gate electrodes of CMOS capacitors

In this study, ultrathin films (thickness of less than 20 nm) of titanium nitride (TiN) to be used as gate electrodes for CMOS (Complementary Metal Oxide Semiconductor) technology were obtained. These ultrathin films were obtained by electron beam evaporation of ultrathin layers (1 or 2 nm thick) of titanium (Ti) followed by ECR (Electron Cyclotron Resonance) plasma nitridation of nitrogen (N₂). After deposition and nitridation of the titanium, in order to prevent oxidation of the films, in the same nitriding ECR reactor, a-Si:H (hydrogenated amorphous silicon) films were deposited by CVD (Chemical Vapor Deposition) using SiH₄/Ar plasma. These films of a-Si:H were implanted with phosphorus (P⁺) and annealed by rapid thermal annealing to turn them n⁺ dopped and polycrystalline. Thus, MOS metal gate electrodes were formed with n⁺ Poly-Si/TiN structures.