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Publication Citation: The Role of Space Charge in Scanned Probe Oxidation

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Author(s): John A. Dagata;
Title: The Role of Space Charge in Scanned Probe Oxidation
Published: January 01, 1998
Abstract: The growth rate and electrical character of nanostructures produced by scanned probe oxidation are investigated by integrating an in-situ electrical force characterization technique, scanning Maxwell-stress microscopy, into the fabrication process. Simultaneous topographical, capacitance, and surface potential data are obtained for oxide features patterned on n- and p-type silicon and titanium thin-film substrates. The electric field established by an applied voltage pulse between the probe tip and substrate depends upon reactant and product ion concentrations associated with the water meniscus at the tip-substrate junction and within the growing oxide film. Space-charge effects are consistent with the rapid decline of high initial growth rates, account for observed doping and voltage-pulse dependencies, and provide a basis for understanding local density variations within oxide features. An obvious method for avoiding the build-up of space charge is to employ voltage modulation and other dynamic pulse-shaping techniques during the oxidation pulse. Voltage modulation leads to a significant enhancement of the growth rate and to improvements in the aspect ratio compared with static voltage pulses.
Citation: Applied Physics
Volume: 84(12)
Pages: pp. 6891 - 6900
Keywords: anodic oxidation;scanned probe microscopy;scanning Maxwell-stress microscopy;silicon;titanium
Research Areas: Metrology, Manufacturing