Reactively sputtered Ti-Si-N films .2. Diffusion barriers for Al and Cu metallizations on Si

Ti-Si-N films synthesized by reactively sputtering a TiSi2, a Ti5Si3, or a Ti3Si target in Ar/N-2 gas mixture were tested as diffusion barriers between planar (100) Si substrates and shallow n(+)p Si diodes, and Al or Cu overlayers. The stability of the Ti-Si-N barriers generally improves with increasing nitrogen concentration in the films, with the drawback of an increase in the film's resistivity. Ti34Si23N43 sputtered from the Ti5Si3 target is the most effective diffusion barrier among all the Ti-Si-N films studied. It works as an excellent barrier between Si and Cu. A film about 100 nm thick, with a resistivity of around 700 mu Omega cm, maintains the stability of Si n+p shallow junction diodes with a 400 nm Cu overlayer up to 850 degrees C for 30 min vacuum annealing. When it is used between Al and Si, the highest temperature of stability achievable with a 100-nm-thick film is 550 degrees C. A thermal treatment at 600 degrees C causes a severe intermixing of the layers. The microstructure, atomic density, and electrical resistivity of these films are described in an accompanying Part I. (C) 1997 American Institute of Physics.