Grain growth of copper films prepared by chemical vapour deposition

Copper films having thickness 600 nm were prepared on TiN using chemical vapour deposition (CVD). The deposited films were annealed at various temperatures (350-550 degrees C) in Ar and H-2(10%)-Ar ambients. The changes in the grain size of the films upon annealing were investigated. Annealing in an H-2(10%)-Ar ambient produced normal grain growth; annealing in an Ar ambient caused grain growth to stop at 550 degrees C. The grain size followed a monomodal distribution and the mean size increased in proportion to the square root of the annealing time, indicating the curvature of the grain is the main driving force for grain growth. Upon annealing at 450 degrees C for 30 min in an H-2(10%)-Ar ambient, the average grain size of the film increased from 122 nm to 219 nm, and the resistivity decreased from 2.35 mu Ohm cm to 2.12 mu Ohm cm at a film thickness of 600 nm.