Effect of HCl cleaning on InSb–Al 2 O 3 MOS capacitors

In this work, the role of HCl treatments on InSb surfaces and InSb–Al 2 O 3 dielectric interfaces is characterised. X-ray photoelectron spectroscopy measurements indicate that HCl diluted in and rinsed with isopropanol (IPA) results in a surface layer of InCl 3 which is not present for similar HCl-water processes. Furthermore, this InCl 3 layer desorbs from the surface between 200 °C and 250 °C. Metal–oxide–semiconductor capacitors were fabricated using atomic layer deposition of Al 2 O 3 at 200 °C and 250 °C and the presence of InCl 3 was associated with a +0.79 V flatband voltage shift. The desorption of the InCl 3 layer at 250 °C reversed this shift but the increased process temperature resulted in increased interface-trapped charge ( D it ) and hysteresis voltage ( V H ). This shift in flatband voltage, which does not affect other figures of merit, offers a promising route to manipulate the threshold voltage of MOS transistors, allowing enhancement-mode and depletion-mode devices to be fabricated in parallel.