YON界面钝化层改善HfO2/Ge界面特性的研究

摘要

本文采用YON界面钝化层来改善HfO2栅介质Ge metal-oxide-semiconductor (MOS)器件的界面质量和电特性.比较研究了两种不同的YON制备方法:在Ar+N2氛围中溅射Y2O3靶直接淀积获得以及先在Ar+N2氛围中溅射Y靶淀积YN再于含氧氛围中退火形成YON.实验结果及XPS的分析表明,后者可以利用YN在退火过程中先于Ge表面吸收从界面扩散的O而氧化,从而阻挡了O扩散到达Ge表面,更有效抑制了界面处Ge氧化物的形成,获得了更优良的界面特性和电特性:较小的CET(1.66 nm),较大的k值(18.8),较低的界面态密度(7.79 ×1011 eV-1cm-2)和等效氧化物电荷密度(-4.83×1012 cm-2),低的栅极漏电流(3.40×10-4 A/cm2@Vg=Vfb+1 V)以及好的高场应力可靠性.%the effects of YON interfacial passivation layer (IPL) on the interfacial and electrical properties of Ge metal-oxide-semiconductor (MOS) capacitor with HfO2 gate dielectric are investigated.The YON IPL is fabricated by two different approaches:one is to sputter Y2O3 target in Ar + N2 to directly form YON,and another is to sputter Y target in Ar + N2 to deposit YN first and then perform annealing in N2 + O2 to convert YN to YON.Experimental results and XPS analyses indicate that the latter could suppress formation of the Ge oxides at/near the YON/Ge interface more efficiently to achieve more excellent interfacial and electrical properties as compared to the former,since the YN can absorb oxygen diffused to the interface to form YON prior to the Ge surface.As a result,small capacitance equivalent thickness (1.65 nm),high k value (18.9),low interface-state density (7.79 × 1011 cm-2 eV-1) and equivalent oxide-charge density (-3.54 × 1012 cm-2),small gate leakage current density (2.74 × 10-4 A/cm2 at Vg =Vfb + 1 V) and good high-field stressing reliability have been obtained.