Interface trap density evaluation of off-angle Si(110)/SiO 2 MOS structures

Abstract We study MOS capacitors on vicinal Si(110) substrates to evaluate the influence of off-angle on the SiO 2 /Si interface properties by using the conductance method and the high-low frequency method. We examine the (100) orientation with no off-angle and the (110) orientation with seven different off-angles, 0°, 0.19°, 0.27°, 0.33°, 0.78°, 1.0°, and 8.0° ((551) orientation). Across all (110) off-angles, the fixed charge density and the surface potential fluctuation show no significant dependence on off-angles. Although the interface trap density exhibits a slight dependence on off-angles, the trend is insignificant when considering MOSFET performance. These results suggest that slight off-angle deviation does not critically affect the interface properties of (110) surfaces, offering process robustness and design flexibility in (110)-channel MOSFETs. In addition, the (551) surface exhibits a lower interface trap density compared to (110) surfaces with smaller off-angles, indicating its potential for high-quality interfaces.