In this paper, we have studied the effect of selective anodic oxidation on ultrathin (22-31Å ) silicon dioxide grown at different temperatures ranging from 600 °C to 875 °C, on both p- and n-type substrate. A model based on the concept of filling of pinholes by selective anodic oxidation is presented to quantitatively explain the reduction in the gate leakage current of the MOS capacitors after selective anodic oxidation. © 2005 IEEE.

Amitava Dasgupta

Department of Electrical Engineering

Nandita Dasgupta

Vaibhav G. Marathe

Anodic oxidation

Electric potential

Leakage currents

Semiconductor device manufacture

Semiconductor device models

Substrates

GATE LEAKAGE CURRENT

ULTRATHIN GATE OXIDES

MOS capacitors

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A model to study the effect of selective anodic oxidation on ultrathin gate oxides

IEEE Transactions on Electron Devices

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. © 2006 Taylor & Francis Group, LLC.

IETE Journal of Research

Improvement in the interfacial properties and electrical characteristics of ultrathin SiO2 by selective AC anodisation

The presence of weak spots and pinholes in ultrathin gate oxides significantly increases the leakage current, thereby degrading the device performance. This paper proposes a method, which identifies the weak spots in thermally grown gate oxide and repairs them by selective anodization. By controlling the applied voltage, it is ensured that current flows only through the weak spots in the oxide during anodization. Anodic oxide therefore grows over these weak spots, improving the reliability of the oxide without increasing the gate oxide thickness. Significant improvement in electrical characteristics was observed in the gate oxides treated by anodic oxidation.

IEEE Electron Device Letters

Improvement in electrical characteristics of ultrathin thermally grown SiO2 by selective anodic oxidation

Journal of Applied Physics

Enhancement of the effective tunnel mass in ultrathin silicon dioxide layers

Determination of deep ultrathin equivalent oxide thickness (EOT) from measuring flat-band C-V curve

Thin-gate oxides prepared by pure water anodization followed by rapid thermal densification

Applied Physics Letters

Direct extraction of the electron tunneling effective mass in ultrathin SiO2

Journal	IEEE Transactions on Electron Devices
ISSN	00189383
Open Access	No