Influence of Nitrogen Content in WN[sub x] on Its Thermal Stability and Electrical Property as a Gate Electrode

Abstract

The effects of nitrogen concentration on the thermal stability and electric properties of the film as the gate electrode are investigated. is deposited by using reactive radio frequency sputtering, and films with composition of , , and are obtained at 10, 25, and 40% of partial flow ratio, respectively. The crystal structure of the film indicates that this film is a mixture of , while and films both show the phase. After annealing in ambient at , the surface of the film reveals only the W–O bonding but no W–N bonding. In addition, oxygen diffuses from into and leads to the formation of a mixing layer. Subsequently, flatband voltage of the metal oxide semiconductor capacitor shifts positively after annealing at . After annealing at , and films exhibit better resistance to oxidation than the film, regardless of the surface of the film or the interface between and . Resistivity of all films increases after annealing and also increases with increasing nitrogen content in the films. However, neither the nitrogen content in the nor the postmetal annealing affect the leakage current of capacitors at both positive and negative biases.