氧空位迁移造成的氧化物介质层时变击穿的蒙特卡罗模拟  

Monte Carlo simulation of time-dependent dielectric breakdown of oxide caused by migration of oxygen vacancies

作　　者：栗苹[1] 许玉堂[1] 

机构地区：[1]北京理工大学机电学院,北京100081

出　　处：《物理学报》2017年第21期357-363,共7页Acta Physica Sinica

摘　　要：基于氧空位在金属氧化物内部迁移的微观机理,利用蒙特卡罗方法建立了一种新型的可模拟金属氧化物介质时变击穿的模拟工具.利用建立的模拟工具研究了界面形成氧空位迁移功函数对介质层击穿行为的影响.该工具可应用于金属氧化物半导体晶体管栅介质击穿研究并准确评估其可靠性.In this article, the Monte Carlo method is used to study the formation and migration of oxygen vacancies in metal oxide dielectric. The time-dependent breakdown of the dielectric is simulated. In the direction of the electric field across the metal oxide, the migration barrier and migration work function of oxygen vacancies are found to be reduced by the applied electric field. This finding provides a good foundation for further studying the breakdown mechanism and evaluating the reliability of high κ gate dielectric. The Monte Carlo process is described as follows. Firstly, a three-dimensional metal oxide dielectric layer is built with two-dimensional symmetrical grid, where the thickness of the oxide layer is set to be 9 lattice points and the oxygen vacancies can migrate to the adjacent 8 arbitrary lattice positions in this simulation. Secondly, the possibilities of formation and migration of oxygen vacancies are calculated according to the distribution of oxygen vacancies. Finally, the Monte Carlo method is used to simulate the new distribution of oxygen vacancies. Therefore, we simulate the breakdown process of the metal oxide dielectric layer with different oxygen vacancy migration functions（E_a=1.15, 1.35 eV） at the interface. And we obtain the results as follows. 1） When the migration function is small, many oxygen vacancies accumulate largely at the forming interface. And the vacancies would migrate from the interface to the dielectric, forming a conductive channel. The breakdown time is determined by the migration barrier of oxygen vacancies in the dielectric. 2） When the migration function of the oxygen vacancies at the interface becomes larger, the formed oxygen vacancies will rapidly migrate to the other interface, and the reverse propagation of the conductive channel causes the dielectric breakdown. Therefore, larger migration function of the oxygen vacancies at the interface can effectively improve its reliability. 3） The original defects within the dielectric will seriously influence th

关 键 词：氧空位 蒙特卡罗 氧化物介质 模拟 

分 类 号：O469[理学—凝聚态物理]