The temperature-dependent current-voltage (I-V-T) technique has been used to study the Ni/Si solid phase reaction by measuring the Schottky barrier height (SBH) inhomogeneity of Ni-silicide/Si Schottky diodes. The experimental results show the strong dependence of SBH inhomogeneity on the Ni/Si solid phase reaction. The SBH distribution of the diodes annealed at 500 and 600℃ can be described by a single-Gaussian function and the diode annealed at 500℃ is found to have the best homogeneity and the smallest leakage current. The SBH distribution of the diodes annealed at 400, 700, and 800℃ can be described by a double-Gaussian function in which the mean value of the second Gaussian function is substantially smaller than that of the dominant Gaussian function. The variation of SBH inhomogeneity, an interface property, is related to the phase evolution process in the Ni/Si solid phase reaction, and verified by reverse I-V measurements. Our results indicate that the I-V-T technique may be developed as a wafer-level testing tool to monitor the silicidation process in the complementary metal-oxide-semiconductor device fabrication.

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.

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.

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 Schottky contact of Co, its silicide and germanosilicide on n-poly-Si0.84Ge0.16 layer, was investigated. Amorphous Si0.84Ge0.16 layer was deposited on n-Si (100) substrate by ion beam sputtering (IBS). The layer was doped through thermal diffusion of phosphorus to fabricate n-poly-Si0.84Ge0.16 thin film. The Schottky diodes were formed by deposition of Co on n-poly-Si0.84Ge0.16 by the IBS technique. Solid-phase reaction between Co and n-poly-Si0.84Ge0.16 by rapid thermal annealing (RTA) as a function of temperature was studied. Phase identification and atomic depth profile were characterized by x-ray diffraction and Auger electron spectroscopy, respectively. The current-voltage and capacitance-voltage characteristics of both as-deposited and annealed Co/n-poly-Si0.84Ge0.16 Schottky diodes were investigated. The results reveal that the Schottky barrier height (SBH) keeps nearly constant with the annealing temperature between 300 and 600℃. The constancy of the SBH confirms the fact that Co and its silicides contacting with the same semiconductor have the close Schottky barrier height.