Chang Mao-Nan, Chen Yung-Kuang, Kao Hung-Yi, Chen Jhih-Yang, Liu Chun-Hsien, Lee Yao-Jen
Department of Physics, National Chung Hsing University, Taichung, 402, Taiwan.
Institute of Nanoscience, National Chung Hsing University, Taichung, 402, Taiwan.
Ultramicroscopy. 2021 May;224:113266. doi: 10.1016/j.ultramic.2021.113266. Epub 2021 Mar 27.
This paper reports a novel investigation of the voltage modulation efficiency (VME) in scanning capacitance microscopy (SCM). A signal intensity model was used to define the VME, which is dependent on the impedance components in an SCM setup. In SCM, the VME was found to play a key mediating role in the close relationship between the signal intensity and the modulation voltage, providing an indicator for the surface treatment and the back-contact process of an SCM specimen. We observed that, for silicon-based specimens, ultraviolet-assisted oxidation and microwave annealing improved the specimen surface and the back-contact, respectively, which increased the VME. It was also found that a high modulation voltage and a large back-contact area may induce a significant stray capacitance around the conductive tip and, hence, lower the VME. The VME degradation not only decreased the SCM signal intensity but also reduced the image contrast in the regions with high carrier concentrations. In addition, our experimental results further revealed that the signal intensity model also provided a promising opportunity to establish a precise and quantitative method for measuring the thickness of insulating layers.
本文报道了对扫描电容显微镜（SCM）中电压调制效率（VME）的一项新研究。使用信号强度模型来定义VME，其取决于SCM设置中的阻抗组件。在SCM中，发现VME在信号强度与调制电压之间的密切关系中起关键的中介作用，为SCM样品的表面处理和背接触过程提供了一个指标。我们观察到，对于硅基样品，紫外线辅助氧化和微波退火分别改善了样品表面和背接触，这增加了VME。还发现，高调制电压和大背接触面积可能会在导电尖端周围感应出显著的杂散电容，从而降低VME。VME的降低不仅降低了SCM信号强度，还降低了高载流子浓度区域的图像对比度。此外，我们的实验结果进一步表明，信号强度模型还为建立一种精确的定量测量绝缘层厚度的方法提供了一个有前景的机会。
