Effects of Annealing Temperature and Nitrogen Content on Effective Work Function of Tungsten Nitride
Journal
IEEE Electron Device Letters
Journal Volume
40
Journal Issue
8
Pages
1237-1240
Date Issued
2019
Author(s)
Abstract
By varying annealing temperature (300°C-400°C) and nitrogen content (x = 0.33, 0.56) in the WNx films, the effective work function of WNx can modulate from 4.29 to 4.91 eV. WNx is deposited on SiO 2 /Si stacks by reactive sputtering. The effective work function increases with increasing annealing temperature and decreases with increasing nitrogen content. The effective work function modulation is due to the dipole formation at the WNx/SiO2 interface. Oxygen diffuses from SiO 2 into WNx during annealing and forms the WNxOy near the interface. The dipole with the direction from WNxOy to WNx is formed because the group electronegativity of WN x O y near the WNx/SiO 2 interface is larger than that of the WNx. The WNx with high nitrogen content can alleviate the oxidation and reduce dipole formation.
Type
journal article