Improvement in the Interfacial Properties and Electrical Characteristics of Ultrathin SiO₂ by Selective AC Anodisation

Abstract

In this paper we have studied the effect of selective anodisation under ac bias on ultrathin (2–2.75 nm) silicon dioxide grown at 800°C. It is shown that ac anodisation is more effective in improving the electrical properties of the ultrathin oxide compared to selective anodisation carried out under dc condition. Unlike dc anodisation, which only repairs the pinholes but does not improve the interfacial properties, ac anodisation is found to reduce the density of interface states. The efficacy of ac anodisation is found to depend on the ac signal frequency and best results have been obtained at a frequency of 5 kHz.

Indexing terms:

• MOS
• Anodisation
• Reliability

Additional information

Notes on contributors

Binsu J Kailath

Binsu J Kailath received her BTech degree from Calicut University, Kerala in 1992 in Electronics & Communication Engineering and MTech in Microelectronics & VLSI Design from the Department of Electrical Engineering, IIT Madras in 2001. Currently she is working for her PhD Degree in the Department of Electrical Engineering, IIT Madras. Since 1993, she has been a lecturer in College of Engineering, Chengannur, Kerala. Her field of research includes ultrathin gate oxides for MOS devices.

Amitava Dasgupta

Amitava Dasgupta received the BE degree in Electronics and Telecommunication Jadavpur University, Kolkata, India in 1982, MTech degree in Electrical Engineering from IIT Madras in 1984 and PhD from IIT, Kharagpur in 1988. His PhD dissertation was on analytical modeling of small, geometry MOSFETs with nonuniformly doped channels. He joined as a Lecturer in IIT Kharagpur in the same year. He has been a Faculty member in the Department of Electrical Engineering, IIT Madras since 1993 and is currently a Professor. As a DAAD Fellow, he worked at the Institut für Hochfrequenztechnik, Darmstadt, Germany during 1991–92 and again in 1997. His research interests are in the areas of Semiconductor Device Modelling and Technology as well as MEMS. He has abount seventy research publications in International Journals and Proceedings of International Conferences and has co-authored a book on Semiconductor Devices-Modelling & Technology.

Nandita Dasgupta

Nandita Dasgupta received the BE degree Electronics and Telecommunication Engineering from Jadavpur University, Kolkata, India in 1982, MTech in Electrical Engineering and PhD degrees fron IIT Madras in 1984, and 1988 respectively. Her PhD dissertation was on high pressure oxidation of silicon and GaAs. She was awarded Alexander von Humboldt Fellowship in 1991 and spent one year in Technische Hochschule Darmstadt, Germany. Since 1993, she has been a Faculty member in the Department of Electrical Engineering IIT Madras and is currently a Professor. Her research interest is in the area of Semiconductor Device Technology and Modelling as well as Micro-Electro-Mechanical Systems (MEMS). She has more than sixty research Publications in International Journals and Proceedings of International Conferences and has co-authored a book on Semiconductor Devices-Modelling & Technology.