Conventional dopant diffusion technique has been successfully employed to dope SiGe films deposited by ion-beam sputtering (IBS). The deposited a-SiGe films can be doped to both p and n types after boron and phosphorous diffusions at a temperature range of 850-1000℃. The doping process is accompanied by crystallization of the a-SiGe film. Electrical properties of the doped SiGe films have been characterized by a four-point probe and Hall measurements. Hall mobilities as high as 13 and 31cm2/V·s have been obtained in boron-and phosphorous-doped polycrystalline SiGe films, respectively.

Schottky and pn junction diodes with good rectifying characteristics have been prepared based on the polycrystalline SiGe (poly-SiGe) thin film deposited by the ion-beam-sputtering (IBS) technique. Boron and phosphorus diffusion techniques have been used to dope and crystallize as-deposited amorphous SiGe film. Rectification ratios as high as 4000 and 1800 have been achieved in Pt/n-poly-SiGe and Ti/p-poly-SiGe Schottky diodes, respectively, while rectification ratio higher than 1500 and breakdown voltage higher than 200V have been achieved in poly-SiGe pn junction diodes. Schottky barrier height has been determined to be 0.62 and 0.59 eV for Pt/n-poly-Si0.81Ge0.19 and Ti/p-poly-Si0.81Ge0.19 contacts, respectively, which indicates that the band alignment of poly-SiGe may be substantially different from that of epitaxial SiGe.

The electrical and materials properties of～20nm nickel silicide films, formed at 300℃, on n+/p and p+/n junctions are investigated. The sheet resistance of the silicide on p+/n junctions is found to be more than twice as high as that of the silicide on n+/p junctions. Cross section transmission electron microscopy, Rutherford backscattering spectroscopy, and x-ray photoelectron energy spectroscopy reveal that a pure Ni2Si layer forms on n+/p junctions while a thicker Ni2Si/NiSi double layer (～60% Ni2Si) forms on p+/n junctions. But the electrical differences are found to correlate only with differences in grain size and dopant concentration in the silicide.

Thermal stability, phase and interface uniformity of Ni-silicide are some key issues for NiSi Salicide technology. The improved stability of NiSi was achieved by Ni/Pt/Si and Ni/Pd/Si reaction. The increase of thermal stability can be explained by classical nucleation theory. The phase and interface uniformity of Ni-silicides formed by Ni-Si solid-state reaction were characterized by X-ray diffraction (XRD) and temperature-dependent current-voltage (I-V-T) techniques. Results show that the Schottky barrier height (SBH) inhomogeneity characteristic has strong dependence on annealing temperature for Ni-silicide formation. Deep level transient spectroscopy (DLTS) measurement shows that annealing at relatively low temperature may cause electrically active deep level defects in the film. These results show that choosing a proper annealing temperature for Ni/Si silicidation will be very important for device performance.

Reaction characteristics of ultra-thin Ni films (5nm and 10nm) on undoped and highly doped (As-doped and B-doped) Si (100) substrates are investigated in this work. The sheet resistance (Rs) measurements confirm the existence of a NiSi salicidation process window with low Rs values within a certain annealing temperature range for all the samples except the one of Ni (5nm) on P+-Si (100) substrate (abnormal sample). The experimental results also show that the transition reaction to low resistivity phase NiSi is retarded on highly doped Si substrates regardless of the initial Ni film thickness. Micro-Raman and x-ray diffraction (XRD) measurement show that NiSi forms in the process window and NiSi2 forms in a higher temperature annealing process for all normal substrates. Auger electron spectroscopy (AES) results for the abnormal sample show that the high resistivity of the formation film is due to the formation of NiSi2.