Effect of HCl cleaning on InSb-Al2O3 MOS capacitors

• Published in: Semiconductor science and technology 2019-03, Vol.34 (3)
• Main Authors: Vavasour, Oliver J, Jefferies, Richard, Walker, Marc, Roberts, Joseph W, Meakin, Naomi R, Gammon, Peter M, Chalker, Paul R, Ashley, Tim
• Format: Article
• Language: English
• Subjects: ALD; HCl; III-V; InSb; MOSCAP
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/1361-6641/ab0331

In this work, the role of HCl treatments on InSb surfaces and InSb-Al2O3 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 InCl3 which is not present for similar HCl-water processes. Furthermore, this InCl3 layer desorbs from the surface between 200 °C and 250 °C. Metal-oxide-semiconductor capacitors were fabricated using atomic layer deposition of Al2O3 at 200 °C and 250 °C and the presence of InCl3 was associated with a +0.79 V flatband voltage shift. The desorption of the InCl3 layer at 250 °C reversed this shift but the increased process temperature resulted in increased interface-trapped charge (Dit) and hysteresis voltage (VH). 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.