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用氮化硼和乙硼烷作扩散源,将硼扩散到5.5微米厚的多晶硅中。扩散深度与扩散时间的平方根成正比。多晶硅层中的硼扩散可用熟知的补余误差函数表示。硼源用乙硼烷时多晶硅中硼的扩散系数,比用氮化硼时要大,而且在实验范围内比单晶硅衬底中要大10～50倍。在1050℃用乙硼烷作硼源在单晶硅衬底中硼的扩散系数,用氮化硼和乙硼烷作硼源时在多晶硅中硼的扩散系数分别为:8.86×10~(-14),1.17×10~(-12)和1.95×10~(-12)厘米~2/秒。在以上情况中,硼的扩散系数的激活能分别为3.42,2.39和2.51电子伏。
Boron nitride and diborane are used as diffusion sources to diffuse boron into 5.5 micron thick polysilicon. The depth of diffusion is proportional to the square root of the diffusion time. Boron diffusion in the polysilicon layer can be expressed by the well-known residual error function. The diffusion coefficient of boron in polycrystalline silicon with boron source for boron source is larger than that of boron nitride, and is 10 to 50 times larger than that of single crystal silicon substrate in the experimental range. The diffusion coefficient of boron in monocrystalline silicon substrate with diborane as the boron source at 1050 ℃ and the diffusion coefficient of boron in polycrystalline silicon with boron nitride and diborane as boron source are respectively 8.86 × 10 ~ 14), 1.17 × 10 ~ (-12) and 1.95 × 10 ~ (-12) cm ~ 2 / s. In the above case, the activation energies of boron diffusion coefficients are 3.42, 2.39 and 2.51 electron volts, respectively.