Influence of substrate bias on the microstructure and internal stress in Cu films deposited by filtered cathodic vacuum arc

Copper films were deposited by a novel off-plane double bend filtered catho dic vacuum arc technique at ambient temperatures. X-ray diffraction (XRD) a nd atomic force microscopy (AFM) are used to characterize the film's struct ure and surface morphology. The substrate bending method was used to study the internal stress. The influence of substrate bias on the surface morphol ogy, grain size, crystalline structure, and internal stress was systematica lly studied. XRD results indicate that all the deposited Cu. films exhibit face-centered cubic-type (fcc) crystallite structure with (111) preferred o rientation growth. The increase of substrate bias results in the improvemen t of (111) preferred orientation. At the substrate bias of 0 V, the deposit ed films are composed of nano-sized columnar grains, which contribute to th e tensile stress in the deposited films. The grain size and surface roughne ss increase gradually with increasing substrate bias up to -200 V. Further increase of substrate bias results in the drastic decrease of grain size an d surface roughness due to self-sputtering. The internal stress in the depo sited films is also strongly dependent on the substrate bias. The increase of substrate bias results in the decrease of tensile stress in the deposite d films, and the transition of tensile to compressive stress at the substra te bias of -300 V. Further increase of substrate bias results in the linear increase of compressive stress in the deposited films. At the substrate bi as of -300 V, dense and stress-free Cu films can be obtained. (C) 2001 Amer ican Vacuum Society.