EFFECT OF N CONTENT ON THE THERMAL STABILITY OF Ta–Si–N THIN FILM BARRIER LAYER

Abstract

Ta–Si–N thin films and Cu/Ta–Si–N thin films were deposited on p-type Si (111) substrates by magnetron reactive sputtering. Then the films were characterized by four-point probe sheet resistance measurement, atomic force microscopy, X-ray diffraction method and scanning electron microscope, respectively. The experimental results show that the sheet resistance of Ta–Si–N thin film increases with N content. And the surface roughness of the thin film first decreases and then increases with N content. By increasing the N content, the diffusion barrier property of Ta–Si–N thin film can be improved; however, this improvement is not evident when N content beyond 56%. The as-deposited Ta–Si thin film is nano-crystalline. When doped with N, the as-deposited thin film becomes amorphous. The crystallization of Ta–Si–N thin film occurs again at high temperature. Cu atoms diffuse through grain boundaries of Ta–Si–N thin film into Si , and this leads to failure of the diffusion barrier.