Si_（83）Ge_（17）/Si压应变衬底上HfAlO_x栅介质薄膜微结构、界面反应和介电性能研究

本文研究了射频磁控溅射沉积在p-Si83Ge17/Si（100）压应变衬底上HfAlOx栅介质薄膜的微结构及其界面反应,表征了其各项电学性能,并与相同制备条件下沉积在p-Si（100）衬底上薄膜的电学性能进行了对比研究.高分辨透射电子显微镜观测与X射线光电子能谱深度剖析表明600°C高温退火处理后,HfAlOx薄膜仍保持非晶态,但HfOx纳米微粒从薄膜中分离析出,并与扩散进入膜内的Ge,Si原子发生界面反应生成了富含Ge原子的HfSiOx和HfSix的混合界面层.相比在相同制备条件下沉积在Si（100）衬底上的薄膜样品,Si83Ge17/Si（100）衬底上薄膜的电学性能大幅提高：薄膜累积态电容增加,有效介电常数增大（～17.1）,平带电压减小,？1V栅电压下漏电流密度J减小至1.96×10？5A/cm2,但电容-电压滞后回线有所增大.Si83Ge17应变层抑制了低介电常数SiO2界面层的形成,从而改善了薄膜大部分电学性能;但混合界面层中的缺陷导致薄膜界面捕获电荷有所增加.

Microstructures, interfacial reactions and dielectric properties of HfAIOx film on compressively strained SisaGe17/Si substrate

Microstructures, interracial reactions and dielectric properties of HfA1Ox gate dielectric films deposited on compressively strained Si83Ge17/Si substrate by using radiofrequency magnetron sputtering have been investigated. HRTEM images show that RT-deposited HfA1Ox films remain amorphous even after annealing at 600℃ in oxygen atmosphere for 30 rain. XPS depth profile investigations reveal that nonstoichiometric HfOx nanoclusters have separated from amorphous HfA1Ox matrix during the post annealing process, and reacted with Si and Ge atoms, which diffuse from Si83Ge17 layer into HfA1Ox film, to create a compound interfacial layer containing HfSiOx, HfSix and Ge atoms. Comparison experiment reveals that under the same optimized conditions （room temperature growth in 3 Pa Ar ambient with working power of 100W and thermal annealing treatment in 02 atmosphere at 600℃ for 30 min）, dielectric properties of HfA1Ox films on p-Si83Ge17/Si（100） substrate are better than that on p-Si（100） substrate, such as relatively larger accumulation capacitance, larger effective permittivity（-17.71）, lower flat band voltage （-0.75 V）, and lower leakage current density （1.96x10-5 Acm-2 at -1 V gate voltage）. However, the hysteresis of capacitance- voltage curves for HfA1Ox films on p-Si83GelT/Si（100） become larger. It is argued that the strained Si83Ge17 layer depresses the formation of the low-dielectric constant SiO2 in the mixed interfacial layer with a relatively higher permittivity （- 15.84）, and consequently improves the dielectric properties of HfA1Ox films. However, defects in the mixed interfacial layer result in an increase of the trapped charge density.