Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Articles
Silicon Chemical Oxide Growth by a Novel Wet Treatment in Aqueous Chlorine Solutions
Marius CHEMLADidier LEVYSébastien PETITDIDIERFrançois ROUELLESandrine ZANNA
Author information
JOURNAL FREE ACCESS

2004 Volume 72 Issue 4 Pages 238-245

Details
Abstract

For the wet cleaning of silicon surfaces, a few new reactants, such as ozone dissolved in UPW, have been proposed to replace the original RCA process using H2O2 solutions. In the present work we describe, for the first time, the mechanism of silicon surface oxidation by dilute solutions of elemental chlorine. Upon reaction with this highly oxidizing agent, the open circuit potential shifted immediately to positive values, the effect being identical for both n- and p-type Si substrates. The surface transformation was firstly investigated by electrochemical impedance spectroscopy which showed successive semicircles representing RC equivalent circuits, revealing a gradual growth of an insulating layer. XPS recordings demonstrated unequivocally the formation of a pure and uniform chemical oxide layer, the possible contamination by Cl element being negligible. The analysis of the charge transfer reaction by voltammetry led to the conclusion that the exchange between the semiconductor and the solution involved positive holes. The reduction current, at a negative bias potential, was extremely small with p-type Si as a consequence of a depletion layer appearance. On the contrary, in n-type substrates, an accumulation region was formed, so that the electric field, as high as 107 V cm-1, will promote a conduction mode through the insulating oxide layer. This novel technique of surface treatment seems promising with respects to the economy and environmental requirements, and also for the possible subsequent growth of multi-layer high-k dielectric structures.

Content from these authors
© 2004 The Electrochemical Society of Japan
Previous article Next article
feedback
Top