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半导体热氧化过程中,不可避免会沾污Na离子,造成MOS电容的C-V曲线平带电压漂移。在1 200℃下热氧化,生成SiC/SiO2界面,进而制作MOS电容。采用高电压偏置,在高温度条件下作用于MOS电容;利用Keithley590C-V分析仪,测量其C-V曲线。计算出氧化层Na离子密度为2.26×1012/cm2,高温负高压偏置不能完全恢复MOS电容的C-V特性,且高压偏置处理后的MOS电容在积累区的电容值减小,与Si材料MOS的情况不同。主要原因是SiC氧化层和界面质量较差,在高温和高压下弱键断裂、固定电荷重新分布。
Semiconductor thermal oxidation process, will inevitably stained Na ions, causing the MOS capacitor C-V curve flat band voltage drift. Thermal oxidation at 1200 ℃ generates a SiC / SiO2 interface, which in turn produces a MOS capacitor. Using high-voltage bias, the role of MOS capacitors in high temperature conditions; the use of Keithley590C-V analyzer to measure the C-V curve. Calculated the oxide ion Na ion density of 2.26 × 1012 / cm2, high temperature negative high voltage bias can not fully restore the CV characteristics of MOS capacitors, and the high-voltage bias after the MOS capacitor capacitance in the accumulation area decreases, and Si material MOS The situation is different. The main reason is the poor quality of the SiC oxide layer and interface, the weak bond breaking at high temperature and pressure, and the redistribution of fixed charges.