4H-SiC MOS电容栅介质经NO退火电流导通机理研究

Gate Leakage Current Conduction Mechanisms in NO Annealing and Dry Gate Oxides Grown on 4H-SiC

本文对进行NO退火和非NO退火的SiC MOS电容的栅泄漏电流的导通机理进行了分析,研究表明在高场下经过NO退火和未经过NO退火的样品的栅泄露电流都由Fowler-Nordheim(FN)隧穿决定,经过NO退火的势垒高度为2.67eV,而未经过NO退火的样品势垒高度为2.54eV,势垒高度的增加说明了氮化的作用.在中度电场区域,通过拟合分析发现此区域的栅泄漏电流主要由Poole-Frenkel发射(PF)决定,并不受陷阱辅助隧穿trap assisted tunneling(TAT)的影响.同时C-V特性也明显看出NO退火对界面质量的影响.

Current conduction mechanisms of SiC MOS capacitors on n-type 4H-SiC with or without NO annealing were investigated in this work.Results show that FN tunneling is the dominate current conduction mechanism in the high electrical field,and the barrier height is2.67 eV and 2.54 eV respectively for experiencing NO annealing and without NO annealing.A higher barrier height for NO annealing sample indicate the effect of N element on the SiC/SiO2 interface quality.In intermediate oxide electrical field,instead of Trap-assisted tunneling PF emission dominate the current conduction in this region.And the C-V characteristics also show the advantages of NO annealing on the SiC/SiO2 characteristics.This work will provide significant foundation for the key processing technology of SiC MOS device.