STUDY OF TANTALUM-BASED DIFFUSION-BARRIERS BETWEEN AL AND SI

We have investigated sputter-deposited TaSi(x), TaSi(x)N(y), and TaSi( x)N(y)/TaSi(x) thin films as the diffusion barrier between aluminum an d silicon. The sheet resistance of the films was measured. The structu re of the films was determined by transmission electron micrographs an d X-ray diffraction patterns. A thermal stability study was performed by measuring the reverse bias leakage current on n +-p Si junction dio des and the specific contact resistance on n + Si after various sinter ing conditions. We found that the TaSi(x) film in the TaSi(x)N(y)/TaSi (x) bilayer structure showed the advantage of low sheet resistance and low specific contact resistance. The existence of TaSi(x)N(y) in the bilayer structure gives a high resistance to the Al-Si interdiffusion. The bilayer structure is thermally stable up to 530-degrees-C.