全耗尽SOI MOSFET辐照导致的阈值电压漂移模型

A New Threshold Voltage Shift Model Due to Radiation in Fully-Depleted SOI MOSFET

报道了全耗尽SOIMOSFET器件阈值电压漂移与辐照剂量和辐照剂量率之间的解析关系 .模型计算结果与实验吻合较好 .该模型物理意义明确 ,参数提取方便 ,适合于低辐照总剂量条件下的加固SOI器件与电路的模拟 .讨论了抑制阈值电压漂移的方法 .结果表明 ,对于全耗尽SOI加固工艺 ,辐照导致的埋氧层 (BOX)氧化物电荷对前栅的耦合是影响前栅阈值电压漂移的主要因素 ,但减薄埋氧层厚度并不能明显提高SOIMOSFET的抗辐照性能 .

A new approach to model the radiation-induced threshold voltage shift in fully-depleted SOI MOSFET has been implemented for circuit simulations.The model is validated by comparison of simulated and measured post-radiation device characteristics of MOSFETs in the literature.The model has such advantages as simple analytic expression,clear physical meaning,and easy extraction of used parameters.The model can be used as a basic circuit simulation tool for analysing hardened SOI MOS transistors exposed to a nuclear environment in the low-dose range.Additionally,the discussion presented here supports that the large top threshold voltage shift of the fully-depleted MOSFET is attributed to the large radiation induced oxide charge in the buried oxide which was coupled to the top gate.Thinner buried oxides,which are less dose sensitive than thicker ones,can not necessarily improve the radiation hardness of fully-depleted transistors because of the higher coupling effect.