Oxidation characteristics of nanodot and nanobump on TiN thin films by atomic force microscopy

Electrochimica Acta 50 (2005) 2793–2797

Oxidation characteristics of nanodot and nanobump

on TiN thin films by atomic force microscopy

Te-Hua Fang

Department of Mechanical Engineering, Southern Taiwan University of Technology, Tainan 710, Taiwan

Received 18 June 2004; received in revised form 3 November 2004; accepted 8 November 2004 Available online 16 December 2004

Abstract

The electrochemical oxidation characteristics of TiN thin films by atomic force microscopy (AFM) was investigated. The TiN films were produced on silicon substrate by atomic layer chemical vapor deposition (ALCVD). The anodization parameters, such as the anodized voltages, the oxidation times, and how they affected the creation and growth of the oxide nanostructures were explored. The results showed that the height of the TiN oxide dots grew as a result of either the anodization time or the anodized voltage being increased. The oxide growth rate was dependent on the anodized voltage and the resulting electric field strength. Furthermore, the oxide growth rate decreased immediately when the electric field strength reached (2–3)× 107_{V/cm rapidly decrease to a growth rate of 0.}

© 2004 Elsevier Ltd. All rights reserved.

PACS: 66.30.Pa; 81.65.Mq; 68.37.Ps; 82.45.Yz

Keywords: Atomic force microscopy; Nanooxidation; TiN; ALCVD

1. Introduction

During the past decade, scanning probe microscopy (SPM) such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have had a great impact on the development of the nanotechnology because of their demonstrated ability to manipulate atoms on the surface and fabricate nanostructures[1]. Scanning probe anodization is a nanolithographic technique based on the electrochemical oxidation of a specimen with an adsorbed water layer[2]. In particular, an AFM-based local anodization process has been investigated for the fabrication of nanostructures and nanodevices[3,4].

Atomic layer chemical vapor deposition (ALCVD) is a promising technique for growing semiconductor materials with excellent step coverage and excellent thickness unifor-mity by means of atomic level layer-by-layer deposition on a

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E-mail address: [email protected].

large-area wafer[5]. Titanium nitride (TiN) films have been employed for ultra large scale integration (ULSI) because of its high thermal stability, low electrical resistivity and good diffusion barrier characteristics[6].

AFM-induced oxidation on TiN thin films produced TiOxNyoxide structures[7]. However, there is still a lack of

information concerning the surface’s anodic kinetics, growth mechanisms, and the effect of the electric field strength. In this study the AFM tip-induced local anodization on TiN sur-face is presented.

2. Experiment details

The TiN thin films were deposited on a p-type Si(1 0 0) substrate by ALCVD. Before the film’s deposition, the Si wafer was cleaned in a HF solution to remove the native oxide SiO2layer. TiCl4and NH3reaction gases were supplied sequentially during the deposition process. Ar was used as a purge gas to remove the chemical residue with no adsorption 0013-4686/$ – see front matter © 2004 Elsevier Ltd. All rights reserved.

T.-H. Fang / Electrochimica Acta 50 (2005) 2793–2797 2797 growth. The oxide thickness was governed by the electric

field strength and, when the electric field strength ranged be-tween 2× 107to 3× 107V/cm, the growth rate reached 0. The TiN-oxide nanostructures were successfully fabricated and the mechanisms studied during the anodization process lead us to recommend the use of AFM in non-contact mode for performing local anodization lithography.

Acknowledgements

This work was partially supported by National Science Council of Taiwan, under grant no. NSC92-2218-E218-002 and the author like to thank Mr. Shi-Cheng Liao and Sheng-Rui Jian for their technical support.

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