不同氛围溅射HfO_2栅介质薄膜的电学性能和界面微结构

Dielectric properties and interfacial microstructures of HfO_2 films deposited in different ambient by sputtering

本文研究了不同沉积氛围(纯Ar,Ar+O2和Ar+N2)中射频磁控溅射制备HfO2薄膜的介电性能和界面微结构.实验结果表明在纯Ar氛围室温制备的HfO2薄膜具有较好的电学性能(有效介电常数ε-r～17.7;平带电压～0.36 V;1 V栅电压下的漏电流密度～4.15×10-3 A cm-2).高分辨透射电子显微镜观测和X射线光电子能谱深度剖析表明,在非晶HfO2薄膜和Si衬底之间生成了非化学配比的HfSixOy和HfSix混合界面层.该界面层的出现降低了薄膜的有效介电常数,而界面层中的电荷捕获陷阱则导致薄膜电容-电压曲线出现顺时针的回线.

Dielectric properties and interfacial microstructures of HfO2 films deposited by radiofrequency（RT） magnetron sputtering in different ambient have been investigated.It is demonstrated that the dielectric properties of HfO2 film deposited at room temperature in pure Ar ambient（effective dielectric constant is about 17.7;flat band voltage is 0.36 V and leakage current density is about 4.15 × 10？3 A cm？2 at 1 V gate voltage） are better than that of films deposited in Ar＋N2 or Ar＋O2 mixed ambient.Investigated by using high-resolution electron microscope and X-ray photoelectron spectroscopy,the unstoichiometric HfSixOy mixed with HfSix interfacial layers are found to exist between stoichiometric amorphous HfO2 films and Si（100） substrates.These unstoichiometric interfacial layers with low-k are responsible for the decrease of effective dielectric constant of HfO2 films and the clock-wise hysteresis of capacitance-voltage curves of MOS capacitor structures.