Thermal stability of N₂–H₂plasma-treated metal-organic-vapor-deposition TiN in a W/TiN/Ti/Si system

Abstract

We examined the thermal stability of a W/TiN/Ti/Si metallization system by changing the thickness ratios of the plasma-treated (PT) to plasma-untreated regions (5 nm × 6/0 nm, 5 nm × 4/10 nm, 5 nm × 3/15 nm, 5 nm × 2/20 nm and 0/30 nm/nm) for the metal-organic-chemical-vapor-deposition (MOCVD) TiN diffusion barriers. From in situ film stress measurements taken during thermal cycles, the best thermal stability was achieved when about half of the thickness at the bottom of the MOCVD-TiN was N 2 -H 2 PT. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy revealed that this barrier structure successfully prevented the interdiffusion of the diffusing species from the WSi 2 formation at the interface even after thermal annealing at 850 • C for 30 min, and this superior thermal stability was due to the microstructural evolution of the diffusion barrier comprising the amorphous layer for the top half and the oxygen-stuffed crystalline layer at the bottom. From the same plasma-treatment condition, the lowest leakage currents were obtained from both n+ and p+ 10 k array chains of the contacts with a diameter of 350 nm and an aspect ratio of ∼1.