Mechanism of mobility enhancement in Ge p-channel metal-oxide-semiconductor field-effect transistor due to introduction of Al atoms into SiO2/GeO2 gate stack
Mechanism of mobility enhancement in Ge p-channel metal-oxide-semiconductor field-effect transistor due to introduction of Al atoms into SiO2/GeO2 gate stack
复制标题
SiO2/GeO2栅堆叠中引入Al原子提高Ge p沟道金属氧化物半导体场效应晶体管迁移率的机制
DOI：
10.1016/j.mssp.2016.11.014
复制
发表时间：
2016
影响因子：
4.1
通讯作者：
and H. Nakashima
中科院分区：
文献类型：
--
作者：
Y. Nagatomi;T. Tateyama;S. Tanaka;W.-C. Wen;T. Sakaguchi;K. Yamamoto;L. Zhao;D. Wang;and H. Nakashima
本文给出了用物理气相沉积方法在Ge衬底上制备的SiO_2/GeO_2栅叠层的Al-PMA效应的综合结果。金属氧化物半导体(CAP)电容器(CAP)的有效氧化层厚度为~7 nm，Al-PMA的温度范围为300~400℃。用电容-电压法和恒温深能级瞬变谱方法对MOSCAP的平带电压(VFB)、电滞(HT)、界面态密度(DIT)和边界陷阱密度(DBT)进行了表征。未经Al-PMA处理的MOSCAP在SiO_2/GeO_2界面的电偶极子为~−0.8 eV，在300℃Al-PMA处理后电偶极子消失。在300℃Al-PMA处理后，Ht、DIT和Dbt均减小，并保持在300-400℃的温度范围内。另一方面，VFB值随着PMA温度的升高而单调地向正方向移动，这意味着负电荷原子的产生。用飞行时间二次离子质谱仪和X射线光电子能谱方法对不含Al-PMA和含Al-PMA的MOSCAP进行了结构分析。结果表明，Al原子从铝电极扩散到SiO_2膜中，并与GeO_2发生反应。300℃下Al-PMA后偶极子的消失可能与SiO_2/GeO_2界面的结构变化有关。我们还给出了采用PtGe/Ge接触作为源漏的PMA处理的铝栅p沟道MOS场效应管的器件性能。经Al-μ处理后，p-MOSFET的峰场效应迁移率(μh)在325℃达到468cm2/vs，这是由于GeO2/Ge界面附近的电荷密度降低所致。
In this paper, we present comprehensive results on Al-postmetallization annealing (Al-PMA) effect for the SiO2/GeO2gate stack on a Ge substrate, which were fabricated by a physical vapor deposition method. The effective oxide thickness of metal-oxide-semiconductor (MOS) capacitor (CAP) was ~7 nm, and the Al-PMA was performed at a temperature in the range of 300–400 °C. The flat band voltage (VFB), the hysteresis (HT), the interfacial states density (Dit), and the border traps density (Dbt) for MOSCAPs were characterized by a capacitance–voltage method and a constant-temperature deep-level transient spectroscopy method. The MOSCAP without Al-PMA had an electrical dipole of ~−0.8 eV at a SiO2/GeO2interface, which was disappeared after Al-PMA at 300 °C. The HT,Dit, andDbtwere decreased after Al-PMA at 300 °C and were maintained in the temperature range of 300–400 °C. On the other hand, theVFBwas monotonically shifted in the positive direction with an increase in PMA temperature, suggesting the generation of negatively charged atoms. Structural analyses for MOSCAPs without and with Al-PMA were performed by a time-of-flight secondary ion mass spectroscopy method and an X-ray photoelectron spectroscopy method. It was confirmed that Al atoms diffused from an Al electrode to a SiO2film and reacted with GeO2. The dipole disappearance after Al-PMA at 300 °C is likely to be associated with the structural change at the SiO2/GeO2interface. We also present the device performances of Al-gated p-channel MOS field-effect transistors (FET) with PMA treatments, which were fabricated using PtGe/Ge contacts as source/drain. The peak field-effect mobility (μh) of the p-MOSFET was reached a value of 468 cm2/Vs after Al-PMA at 325 °C. Theμhenhancement was explained by a decrease in the total charge densities at/near the GeO2/Ge interface.