Method for forming a low resistivity tungsten silicide layer for metal gate stack applications

摘要

Tungsten silicide layers can be used in CMOS transistors in which the work function of the tungsten silicide layers can be tuned for use in PMOS and NMOS devices. A co-sputtering approach can be used in which silicon and tungsten are deposited on a high dielectric constant gate dielectric layer. The tungsten silicide layer can be annealed at or above a critical temperature to optimize the resistivity of the tungsten silicide layer. In some embodiments, the concentration of as-deposited tungsten silicide can be between 50 at % silicon to 80 at % silicon. The critical temperatures can be lower at higher silicon concentration, such as 700 C. at 63 at % silicon to 600 C. at 74 at % silicon.

主权项

1. A method of forming a film stack, the method comprising:
providing a substrate; forming a first layer above the substrate,
wherein the first layer comprises a dielectric material; forming a second layer on the first layer,
wherein the second layer comprises tungsten and silicon; determining a critical temperature for the second layer,
wherein the critical temperature is a temperature at which a rate of change of second layer resistivity over temperature changes observably; and annealing the second layer at a temperature higher than the critical temperature.