Structural and Electrical Investigation of the Si-SiO2 Interface in Thermally Oxidized Silicon.

Abstract

Abstract : The dependence of fixed oxide charge density (Q sub ss)/q), interface state density (N sub st), and electron spin resonance P sub b signals on thermal oxidation process variables as well as their interrelationship has been investigated. Both n- and p-type silicon substrates having (111) and (100) orientation were employed in this study. Measurement techniques included conventional 1 MHz capacitance-voltage (C-V) analysis, quasistatic C-V analysis, and electron spin resonance. The oxide charges resulting from postoxidation in situ anneal in nitrogen were found to be similar in nature and magnitude to those obtained following a similar treatment in argon. Some reduction in N sub st was observed for thicker oxides following a post-metallization H2 anneal. Strong evidence is obtained for a proportionality between ESR signals and interface states density with varying process parameters modifying the P sub b to N sub st relationship. The effects of iron ion implantation (before or after oxidation) on oxide charges and P sub b signals has also been investigated. This work, in addition to clarifying the relationship between fixed oxide charges, interface states, and ESR P sub b signals, demonstrates the significance of ESR as a tool in the characterization of the Si-SiO2 system. (Author)