埋氧层注氮工艺对部分耗尽SOI nMOSFET特性的影响

研究了埋氧层中注氮后对制作出的部分耗尽SOInMOSFET的特性产生的影响.实验发现，与不注氮的SIMOX基片相比，由注氮SIMON基片制作的nMOSFET的电子迁移率降低了.且由最低注入剂量的SIMON基片制作的器件具有最低的迁移率.随注入剂量的增加，迁移率略有上升，并趋于饱和.分析认为，电子迁移率的降低是由于Si/SiO2界面的不平整造成的.实验还发现，随氮注入剂量的提高，nMOSFET的阈值电压往负向漂移.但是，对应最低注入剂量的器件阈值电压却大于用SIMOX基片制作出的器件.固定氧化物正电荷及界面陷阱密度的大小和分布的变化可能是导致阈值电压变化的主要因素.另外发现，用注氮基片制作出的部分耗尽SOInMOSFET的kink效应明显弱于用不注氮的SIMOX基片制作的器件. 关键词： SOI nMOSFET 氮注入 电子迁移率 阈值电压

Effects of the technology of implanting nitrogen into buried oxide layer on the characteristics of partially depleted SOI nMOSFET

The effects,caused by the process of the implantation of nitrogen in the buried oxide layer of SIMOX wafer,on the characteristics of partially depleted silicon-on-insulator nMOSFET have been studied. The experimental results show that the channel electron mobilities of the devices fabricated on the SIMON (separation by implanted oxygen and nitrogen) wafers are lower than those of the devices made on the SIMOX (separation by implanted oxygen) wafers. The devices corresponding to the lowest implantation dose have the lowest mobility within the range of the implantation dose given in this paper. The value of the channel electron mobility rises slightly and tends to a limit when the implantation dose becomes greater. This is explained in terms of the rough Si/SiO 2 interface due to the process of implantation of nitrogen. The increasing negative shifts of the threshold voltages for the devices fabricated on the SIMON wafers are also observed with the increase of implanting dose of nitrogen. However,for the devices fabricated on the SIMON wafers with the lowest dose of implanted nitrogen in this paper,their threshold voltages are slightly larger on the average than those prepared on the SIMOX wafers. The shifts are considered to be due to the increment of the fixed oxide charge in SiO 2 layer and the change of the density of the interface-trapped charge with the value and distribution included. In particular,the devices fabricated on the SIMON wafers show a weakened kink effect,compared to the ones made on the SIMOX wafers.