Low temperature inorganic chemical vapor deposition of Ti-Si-N diffusion barrier liners for gigascale copper interconnect applications

A new low temperature inorganic thermal chemical vapor deposition process h as been developed for the growth of titanium-silicon-nitride (Ti-Si-N) line rs for diffusion barrier applications in ultralarge scale integration coppe r interconnect schemes. This process employs the thermal reaction of tetrai odotitanium (TiI4), tetraiodosilane (SiI4), and ammonia (NH3) as, respectiv ely, the individual Ti, Si, and N sources. Ti-Si-N films were successfully grown over a broad range of deposition conditions, including wafer temperat ure, process pressure, and TiI4, SiI4, and NH3 flows ranging, respectively, from 350 to 430 degrees C, 0.1-1 Torr, and 2.5-8.0, 2.5-12.5, and 100-250 seem. Film stoichiometry was tightly tailored through independent control o f the Ti, Si, and N source flows. Film properties were characterized by x-r ay photoelectron spectroscopy, Rutherford backscattering spectrometry, tran smission electron microscopy, scanning electron microscopy, x-ray diffracti on, and four-point resistivity probe. Resulting findings indicated that the texture and resistivity of the Ti-Si-N system were dependent on compositio n. In particular, films with a Ti33Si15N51 stoichiometry exhibited a nanocr ystalline TiN phase within an amorphous SiN matrix, highly dense morphology , resistivity of similar to 800 mu Omega cm for 25 nm thick films, and step coverage of similar to 50% in 130 nm wide, 10:1 aspect ratio trenches. Oxy gen and iodine contaminant levels were below, respectively, 3 and 1.4 at. % each. Preliminary copper diffusion-barrier studies indicated that barrier failure for 25 nm thick Ti34Si23N43 films did not occur until after anneali ng for 30 min at 700 degrees C. (C) 2000 American Vacuum Society. [S0734-21 1X(00)07904-X].