| Summary: | 碩士 === 國立交通大學 === 物理研究所 === 91 === In the Si-based semiconductor industry, SiH4, SiH2Cl2, SiHCl3 and SiCl4 are frequently used to grow silicon and SiO2 dielectric thin films. During the film growth, the H2, HCl and SiCl2 molecules are all among the desorption products at different temperature range. Therefore, the detailed understanding of atomic diffusion, self organization, and reactions occurred on the silicon surface with the hydrogen and chlorine coexistence are of technological importance.
This work investigated dynamics and kinetics of the H, Cl/Si(100) and HCl/Si(100) surfaces. To obtain the H- and Cl-covered surface, hydrogen and chlorine were exposed to the clean Si(100) surface sequentially. In this way, the ratio of the hydrogen and chlorine on the surface can be controlled and produced initially more H-Si-Si-H and Cl-Si-Si-Cl species. Alternatively HCl molecules were directly applied. In this case, the amount of hydrogen and chlorine are both fixed at about 0.5 ML. At room temperature, hydrogen and chlorine appear randomly dispersed on the surface in the forms of H-Si-Si-H, Cl-Si-Si-Cl and H-Si-Si-Cl species. Then, we heated the H, Cl/Si(100) and HCl/Si(100) surfaces to various temperatures and applied scanning tunneling microscopy (STM) to observe in real space the evolution of the morphology and atomic arrangement on the surface. Our measurement showed that hydrogen and chlorine move around on the surface between 580K and 650K and coalesce into small 2D hydrogen and chlorine islands, respectively. That is, the two kinds of atoms do not distribute randomly on the Si(100) surface at near thermal equilibrium conditions.
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