Feng Xing-Yao, Liu Hong-Xia, Wang Xing, Zhao Lu, Fei Chen-Xi, Liu He-Lei
Key Laboratory for Wide-Band Gap Semiconductor Materials and Devices of Education, School of Microelectronics, Xidian University, Xi'an, 710071, China.
Nanoscale Res Lett. 2016 Dec;11(1):394. doi: 10.1186/s11671-016-1623-2. Epub 2016 Sep 13.
The mechanism of flat band voltage (VFB) shift for alternate La2O3/Al2O3 multilayer stack structures in different annealing condition is investigated. The samples were prepared for alternate multilayer structures, which were annealed in different conditions. The capacitance-voltage (C-V) measuring results indicate that the VFB of samples shift negatively for thinner bottom Al2O3 layer, increasing annealing temperature or longer annealing duration. Simultaneously, the diffusion of high-k material to interfaces in different multilayer structures and annealing conditions is observed by X-ray photoelectron spectroscopy (XPS). Based on the dipole theory, a correlation between the diffusion effect of La towards bottom Al2O3/Si interface and VFB shift is found. Without changing the dielectric constant k of films, VFB shift can be manipulated by controlling the single-layer cycles and annealing conditions of alternate high-k multilayer stack.
研究了不同退火条件下交替排列的La2O3/Al2O3多层堆叠结构的平带电压（VFB）偏移机制。制备了交替多层结构的样品，并在不同条件下进行退火。电容-电压（C-V）测量结果表明，对于较薄的底部Al2O3层、升高退火温度或延长退火时间，样品的VFB会向负方向偏移。同时，通过X射线光电子能谱（XPS）观察了不同多层结构和退火条件下高k材料向界面的扩散情况。基于偶极子理论，发现了La向底部Al2O3/Si界面的扩散效应与VFB偏移之间的相关性。在不改变薄膜介电常数k的情况下，可以通过控制交替高k多层堆叠的单层循环和退火条件来控制VFB偏移。
