γ射线作用下氧化铪基MOS结构总剂量效应研究

Total dose effect of HfO2 based MOS capacitors under gamma-ray radiation

使用原子层淀积方法得到了7.8nm厚度的HfO2薄膜并通过直接溅射金属铝电极得到了Al/HfO2/SiMOS电容结构,测量得到了HfO2基MOS结构在60Coγ射线辐照前后的电容-电压特性,使用原子力显微镜得到了HfO2薄膜在辐照前后的表面微观形貌,使用X射线光电子能谱方法测量得到了HfO2薄膜在辐照前后的化学结构变化。研究发现,使用原子层淀积方法制备的HfO2薄膜表面质量较高;γ射线辐照在HfO2栅介质中产生了数量级为1012cm^-2的负的氧化层陷阱电荷;HfO2薄膜符合化学计量比,介质内部主要的缺陷为氧空位且随着辐照剂量的增加而增加,说明辐照在介质中引入了陷阱从而导致MOS结构性能的退化。

HfO2 film with the thickness of 7.8nm is deposited on p type silicon by using atomic layer deposition method,and aluminum is sputtered on top of the HfO2 film to form Al/HfO2 /Si MOS structure.The surface morphology of HfO 2 is taken by using atomic force microscopy,and the surface quality is approved to be high with low surface roughness and high uniformity.The radiation induced oxide and interface trapped charge density are in the order of 10 12 cm^-2,which is larger than that in SiO2 with the same equivalent oxide thickness.Moreover,the radiation induced oxide trapped charge density increases with the increase of irradiation total dose,the radiation induced interface trapped charge can be either positive or negative.The chemical structure of the HfO2 film is measured by XPS and oxygen vacancy is found to be the dominant radiation induced traps inside the film HfO2.