低剂量辐照条件下的MOSFET因辐照导致的阈值电压漂移的模拟

Simulating Threshold Voltage Shift of MOS Devices Due toRadiation in the Low-dose Range

推导了MOSFET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MOS器件与电路的模拟。并进一步讨论了MOSFET的辐照敏感性。结果表明 ,尽管PMOS较之NMOS因辐照引起的阈值电压漂移的绝对量更大 ,但从MOSFET阈值电压漂移量的摆幅这一角度来看 ,在低剂量辐照条件下NMOS较之PMOS显得对辐照更为敏感。这一研究结果可能为辐照剂量学提供新的应用思路。

An analytical MOSFET threshold voltage shift model due to radiation in the low-dose range has been developed for circuit simulations.Experimental data in the literature shows that the model predictions are in good agreement.It is simple in functional form and hence computationally efficient.It can be used as a basic circuit simulation tool for analysing MOSFET exposed to a nuclear environment up to about 1Mrad(Si).In accordance with common believe,radiation induced absolute change of threshold voltage was found to be larger in irradiated PMOS devices.However,if the radiation sensitivity is defined in the way we did it,the results indicated NMOS rather than PMOS devices are more sensitive,especially at low doses.This is important from the standpoint of their possible application in dosimetry.