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据研究发现,当采用掺杂多晶硅作为扩散源时,硼与磷会扩散到热生长二氧化硅层中去,这种扩散的快慢与推进气氛有关,在氢气中扩散最快。根据双边界扩散模型,我们计算出了扩散系数。硼在二氧化硅中的扩散系数比磷大约要大两个数量级。这点对于硅栅工艺来说非常重要。在 P 沟硅栅晶体管中.由于硼从掺杂多晶硅栅电极扩散到栅氧化层中去,从而会引起晶体管性能的不稳定。
It has been found that when doped polysilicon is used as the diffusion source, boron and phosphorus diffuse into the thermally grown silicon dioxide layer. The diffusion speed is related to the promoting atmosphere and the fastest diffusion in hydrogen. According to the double boundary diffusion model, we calculate the diffusion coefficient. The diffusion coefficient of boron in silica is about two orders of magnitude larger than that of phosphorus. This is very important for the silicon gate process. In a P-type silicon gate transistor, the performance of the transistor is caused to be unstable due to the diffusion of boron from the doped polysilicon gate electrode into the gate oxide layer.