Local anodic oxidation (LAO) lithography of nanodevices by means of atomic force microscopy

Author(s)

Pablo Roberto Fernández Siles

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2006-03-16

Examining board members

Gilberto Medeiros Ribeiro; Mônica Alonso Cotta; Bernardo Ruegger Neves

• Advisor: José Antonio Brum; Gilberto Medeiros Ribeiro

Abstract

Local Anodic Oxidation of conducting and non-conducting substrates by means of Atomic Force Microscopy has raised in the last years as a solid and versatile lithographic technique for fabrication of devices and structures in a nanometric scale. Although, fundamental aspects, as the kinetics involved during the oxidation, are still under study. The objective of this work is to develop a characterization process of this AFM lithographic technique aiming not only to obtain a better understanding of the kinetics involved in the oxidation process but also be able to determine and quantify the influence of the main processing parameters that control the anodic oxidation reaction in the probe-sample interface. By means of a dynamic oxidation process, where the AFM probe is scanning the sample's surface during the oxidation process, we determine the volumetric growth rates of the oxide patterns as a function of the applied voltage in the probe-sample interface, the humidity and the scanning rate of the microscope. As an example of the potential of this technique, it is implemented for the fabrication of devices in a sub-micrometric scale.The fabrication of nano-scaled devices is developed by means of two stages of lithography, first a course adjustment of microscopic patterns and then a fine adjustment where lines and other geometries are patterned in a scale of dezens of nanometers. The goal of this work is to develop both processes. Fine lithography will be done by means of local anodic oxidation (LAO oxidation) with an Atomic Force Microscopy (AFM). A two-layer (PMMA-Ge) resist structure is proposed here for de½nition of structures in a nanometric scale. The system to be studied is essentially based on the self-assembled quantum dots (QDs). The idea of the implementation of LAO oxidation and growth of QDs is to obtain the best performance of each of these processes, the high precision of local anodic lithography and the clean electronic properties of the QDs, aiming to study electronic properties of a small number of isolated QDs (AU)