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目前多晶硅膜的淀积与其他Si_3N_4、SiO_2等薄膜工艺一样,一般都采用CVD技术,国内生产都是在冷壁常压系统中淀积.本文介绍热壁低压CVD技术,使装片容量增加到常规CVD技术的4到5倍,且膜厚的均匀性好,含氧量低,不用携带气体和加热基座,因此工艺简单,能节省电力与高纯气体,具有较大的经济效果.试验中采用的硅源为20%SiH_4气体,系统压力为0.5～1托,淀积温度为640℃～700℃,SiH_4气流量为25～45毫升/分,淀积膜厚2000～7000埃的多晶硅膜,淀积速率为90～160埃/分.膜厚每增加1000埃,R(?)比值降低约1.2倍,淀积温度每增加20℃,R(?)比值降低约1.3倍.根据电子衍射分析,多晶硅膜的最低淀积温度为600℃左右,一般以640℃至700℃为宜.薄膜表面晶粒大小随淀积温度与膜厚增加而增加.
At present, the deposition of polycrystalline silicon film is similar to that of other Si_3N_4, SiO_2 and other thin film processes, CVD technology is generally used, and domestic production is deposited in a cold wall atmospheric pressure system.This paper introduces hot wall low pressure CVD technology, Conventional CVD technology 4 to 5 times, and the film thickness uniformity, low oxygen content, do not carry gas and heating the base, so the process is simple, can save electricity and high purity gas, with greater economic effect. The silicon source used is 20% SiH 4 gas, the system pressure is 0.5 to 1 Torr, the deposition temperature is 640 to 700 ° C., the flow rate of SiH 4 gas is 25 to 45 ml / min, the polysilicon with the film thickness of 2000 to 7000 angstroms is deposited The R (?) Ratio decreased by about 1.2 times for every 1000 Å increase in film thickness and decreased by about 1.3 times for each 20% increase in deposition temperature.According to the electron Diffraction analysis shows that the minimum deposition temperature of polysilicon film is about 600 ℃, generally 640 ℃ to 700 ℃. The grain size increases with the increase of deposition temperature and film thickness.