Imaging the equivalent oxide thickness of an ultra-thin SiO2 layer for studying the SiO2/Si interface reliability

Yi-Shan Wu^1*, Wei-Jhe Liao², Chiao-Jung Lin¹, Mao-Nan Chang^1,2

¹Institute of Nanoscience, National Chung Hsing University, Taichung, Taiwan
²Department of Physics, National Chung Hsing University, Taichung, Taiwan

* Presenter:Yi-Shan Wu, email:513excellent@gmail.com

Ultraviolet-assisted oxidation (UVO) is a potential method for preparing an ultra-thin oxide film on a silicon-based specimen for cross-sectional scanning capacitance microscopy (SCM). For cross-sectional SCM, the SiO2/Si interface reliability is very important for the analyses of SCM images and scanning capacitance spectroscopy (SCS) profiles. It is well known that the equivalent oxide thickness (EOT) provides a directly indicator for understanding the interface of the gate oxide and the carrier channel. Recently, the EOT of an oxide layer could be evaluated by the signal intensity model of SCM has been reported. In this study, it was established to use SCM to image the EOT of an ultra-thin oxide film formed by UVO. For the as-grown oxide layer, the EOT was about 3.96 nm ± 0.02 nm. After 6 hours of duration time, and the EOT of the oxide layer was about 4.49 nm ± 0.05 nm. The EOT values of the oxide layer were 5.38 nm ± 0.17 nm and 10.00 nm ± 0.15 nm for 12 hours and 24 hours of duration time, respectively. For the oxide layer after various duration time, the EOT images directly showed the EOT distributions, corresponding to the SiO2/Si interface quality.

Keywords: Ultraviolet-assisted oxidation, scanning capacitance microscopy, equivalent oxide thickness