Cobalt And Nickel, And Silicon-germanium Thin Films By Solid State Reaction And Schottky Contact Characteristics

Silicon Germanium (Si1-xGex) is an alloy of semiconductor material, which is formed through the covalent bonding between Si and Ge atoms. Si-based device technology is the mainstream of microelectronics at modern times. Since Si1-xGex can be readily integrated into the current silicon technology, it plays an important role in semiconductor materials and device applications.Monocrystalline Si1-xGex can satisfy the requirements of energy band engineering, the lattice constant, energy gap and dielectric constant etc. can be modified by the change of x value; epitaxial Si1-xGex layer on Si can be used as the base region of Si/Si1-xGex/Si hetrojunction bipolar transistor (HBT), which has a higher cutoff frequency and current gain than that of homojunction Si base transistor; epitaxial Si1-xGex/Si system may also be used in many new device architectures at these days, such as strained Si-CMOS devices, modified doping field effect transistor(MODFET), quantum well metal-oxide-semiconductor field effect transistor(QWMOSFET),etc.Polycrystalline Si1-xGex material has many important applications in modern VLSI process as well. The melting point of Si1-xGex is lower than that of Si, and its temperatures of deposition, crystallization and dopant activation are also lower than that of Si, so Si1-xGex is more suitable for the low temperature process. Polycrystalline Si1-xGex may be used as the gate material of MOSFET, active layer of thin film transistor(TFT), raised source-drain and selective diffusion source and etc.Si1-xGex thin film was deposited by ion beam sputtering (IBS). Its crystallinity was enhanced by recrystallization process. That is a simple, economical and environment-friendly fabrication method. Si1-xGex layer was doped with phosphorus and boron through thermal diffusion at the temperature range of 650-950C and 700-1000C respectively. The diffusion process is concomitant with recrystallization. The crystalline phase of Si1-xGex after diffusion was characterized by X-ray diffraction (XRD) and Raman spectroscopy. The as-deposited Si1-xGex thin film is demonstrated with low crystallinity. The intensity of the three characteristic diffraction peaks, SiGe(111), (220) and (311), were enhanced after diffusion. There is no Raman signal detected from the as-deposited SiGe layer and a typical vibration peak of Ge-Ge appears after diffusion. The Ge mole fraction of 15-16% was determined by Auger electron spectroscopy (AES). The carrier concentration has a relationship with the solid solubility of phosphorus or boron and their segregation behavior between grain and grain boundary. Hall measurement indicated the Hall mobility and carrierconcentration of the SiGe film after diffusion and their correlation with thermal diffusion conditions.The factors affecting solid-phase crystallization were studied. Under the same thermal processing conditions, the SiGe layer bombarded by Argon ion for 3min has a higher crystallinity than the SiGe layer that was intact. The comparative study was performed on crystallization activated by conventional furnace annealing (FA) and rapid thermal annealing (RTA). There is a common point in the two methods of crystallization, that is, it is expected a higher crystallinity in the SiGe layer with the higher annealing temperature and longer annealing duration. As for the FA, the SiGe layer on monocrystalline Si substrate has a higher crystallinity than that on SiC>2 substrate. The thermal annealing effect on average grain size, Hall mobility and carrier concentration was investigated. A disadvantage of FA crystallization of SiGe film was a surface oxidation reaction during annealing process. The crystallinity of SiGe film by RTA was characterized by Raman spectroscopy. And the relationship of SiGe crystallization with the annealing conditions was discussed.A systematic study was carried out on the solid-phase reaction between Co, Ni with poly-SiGe thin film. The phase formation of the reacted layer and depth distribution of elements were respectively characterized by XRD and AES. The rea...