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Voltage‐assisted sodium ion incorporation and transport in thin silicon dioxide films
Author(s) -
Krivec S.,
Buchmayr M.,
Detzel Th.,
Nelhiebel M.,
Hutter H.
Publication year - 2010
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.3240
Subject(s) - silicon dioxide , sodium , ion , thin film , silicon , ion transporter , materials science , chemistry , voltage , chemical engineering , nanotechnology , optoelectronics , electrical engineering , composite material , organic chemistry , metallurgy , engineering
Abstract Na + is a well‐known contaminant in metal‐oxide‐semiconductor field effect transistor devices, which may cause severe changes in their input characteristics. This work is addressed to investigate the incorporation and transport behavior of mobile Na + ions in SiO 2 , representing a material of major importance in semiconductor technology. We design an appropriate model system, to deliberately incorporate Na + ions into a thin SiO 2 film, which is attached on an n‐doped Si wafer. A spin‐coated thin polymer film, doped with sodium triflate in a low concentration, serves as external Na + host matrix. The incorporation is assisted by means of an external voltage. Time of flight–secondary ion mass spectrometry is chosen as the tool for determination of Na + ion location and distribution in SiO 2 . Measurements show that once Na + was incorporated, the enormous internal electrical field in the bulk SiO 2 causes an immediate drift of these ions toward the SiO 2 /Si interface, where a pile up of Na + occurs. The related diffusion part can therefore be neglected. However, this accumulation has a counteracting effect on the electrical field and thus influences the incorporation rate. A comparison between the detected number of Na + ions from potentiostatic and spectrometric data shows good agreement. Copyright © 2010 John Wiley & Sons, Ltd.