Oxidation Properties of Al-Nanostructures on Si Surfaces

Abstract

Al2O3 is a dielectric material with a higher κ-value than SiO2 and thus a potential gate insulator material in future generations of silicon based complementary metalinsulatorsemiconductor devices. A recent report by Guha et al. 1 established the growth of devicequality Si (100)/Al2O3 with good interface properties using atomic-beam epitaxial growth in ultra-high-vacuum. An oxide of a thickness equivalent to 1.6nm of SiO2 was found to have five orders of magnitude less leakage current than the SiO2. The best efforts so far to grow thin to ultra-thin Al2O3 films using chemical precursors (trimethyl-aluminum and water), to establish atomic-layer deposition schemes [2], have met with the problem of growth of an interfacial layer of SiO2, an issue also addressed in [1]. In the present work we have developed a new deposition technique to control the steps of atomic layer deposition of Al2O3 directly on top of silicon surfaces, based on the knowledge of the existence and reactivity of Al-nanostructures on Si (111) and Si (100) surfaces. The measurements of the chemical structure and composition of the species resulting in each step are carried out using high-sensitivity, high-resolution photoelectron spectroscopy, and other related surface techniques.