| Transistor is viewed as a very important amplification and switching device in micro-electric field. It consists of many species, of which high-voltage transistor is playing a key role in national productions. With the development of doping technology, the formation of the base region in high-voltage transistor can be made by B diffusion technology, B-A1 paste-layer diffusion technology, close-tube Ga-diffusion technology and open-tube gallium-diffusion technology.At the initial stage of planar technique, B was employed as ideal diffusion impurity in base-region of NPN Si planar devices because of the match of its solid-solubility and diffusion coefficient in Si with those of P in emission-region, and the good shield effect of SiO2 film to B. But because of the relatively large solubility (5×1020/cm3 at 1000℃) and the small diffusion coefficient, the linear slowly-changed distribution of acceptor B in PN junction can not be formed, which could not cater to the requirement of high-reversal-voltage devics. Thereafter B-A1 paste-layer diffusion technology and close-tube Ga-diffusion technology had been developed, while the former can lead to relatively large the base-region deviation and abruptly varied region in Si, which caused severe decentralization of current amplification parameter β , bad thermal stability and high tr; the latter needed the relatively difficult pack technique, with poor repeatability , high rejection ratio, and poor diffusion quality and production efficiency. In recent years, by use of the characters including high-penetration ability of Ga in SiO2, small diffusion stress in Si, large diffusion efficiency and large solid-solubility, open-tube Ga-diffusion technology in SiO2/Si system was realized. From then on, the above two shortcomings had been overcome. Impurity concentration and junction depth can be accurately controlled and freely adjusted. Both low and high dopant concentration can be gained easily, and ideal distribution of Ga in Si can also be achieved with uniform surface concentration, good repeatability and high eligibility and excellence ratio, which have greatly improved comprehensive performances of the devices. All in all, Ga dopant is superior to other P-type dopants.Yet the outstanding shortcoming of open-tube Ga diffusion is the apparent negative resistance effect in the IC-VCE characteristic curve, which is not what we hope. Even thoughmuch has been devoted to the research of it, the mechanism of the negative resistance effect and the effective means to reduce it are rarely reported. So to understand the negative resistance effect mechanism existing in the base-region of high-reverse-voltage transistor has great theory values and extensive application potential.The structure and property of Si surface and SiO2-Si interface, the diffusion property of Ga in SiO2-Si compound structure and the segregation rule of Ga are summarized in this article, along with the narration of current research of Ga diffusion in Si. By the application analysis of Ga doping in the area of separate device, extensive potential of its application are prospected. Current research of the technique of Ga diffusion and the negative resistance effect of open-tube Ga-diffusion transistor are emphasized.The experiments are described in chapter 2. the experimental instruments, apparatus and the means to prepare all the samples are introduced in the first section. In section 2, the experimental system including the oxidization system and diffusion system, are introduced therein. In section 3, the samples preparation including the pre-deposition, redistribution and re-oxidization, the samples of B doping, and the fabrication of Ga-diffusion transistor, B-diffusion and the transistor formed by B diffusion following Ga diffusion are detailed therein, and the as-prepared samples are analyzed by SIMS, SRP and four point probe.All the experiment analyses are presented in chapter 3, including the lodging of negative resistance effect based on the measurement of the parameters of Ga-diff...
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