溅射压强对a-IGZO薄膜的表面粗糙度、氧空位及电学特性的影响

Effect of the Sputtering Pressure on the Surface Roughness, Oxygen Vacancy and Electrical Properties of a-IGZO Thin Films

摘要:

室温下直流磁控溅射a-IGZO薄膜,详细地研究了溅射压强对薄膜的微结构和电学特性产生的影响.通过AFM分析表明，薄膜的表面粗糙度随溅射压强的增加而增大。XPS分析表明薄膜中氧空位含量的随溅射压强的增加而减少。增加的表面粗糙度和减少的氧空位对a-IGZO薄膜晶体管的特性有着决定性的作用。当溅射压强保持在0.6Pa时，得到的薄膜晶体管的特性最佳，电子的饱和迁移率和门限电压分别是3.32cm2/（V?s）和24.6V。溅射压强是磁控溅射制备IGZO薄膜及其晶体管的关键影响因素。

Abstract:

Thin films of amorphous indium gallium zinc oxide (a-IGZO) were fabricated by DC magnetron sputtering. The influence of sputtering pressure on the microstructures and the electronic properties were investigated in details. AFM characterization on surface morphology demonstrated that the surface roughness increases with the sputtering pressure. The oxygen vacancies of the a-IGZO films changes considerably and were reduced significantly with increasing sputtering pressure, as disclosed by X-ray photoelectron spectroscopy. Both the increased surface roughness and reduced oxygen vacancy are detrimental to the performance of a-IGZO TFTs. From this point of view, the sputtering should be done at a proper pressure of 0.06 Pa in order to ensure the enhanced performance. Specifically, the electron saturation mobility (μsat) and the threshold voltage (VTH) of the a-IGZO TFTs are 3.32 cm2/(V?s) and 24.6V at such a sputtering condition.