Dry etching and oxidation of silicon devices using a multipolar electron cyclotron resonance source.

Abstract

Plasma processing is crucial for the fabrication of ultra-large scale integrated (ULSI) circuits. In this thesis, several new plasma technologies were studied based on the electron cyclotron resonance (ECR) plasma source. The ECR source can generate high density plasmas with low energy ions at low pressure. Since the ion density and ion energy in this plasma system can be controlled independently, it provides the additional flexibility needed to meet the multiple requirements of high density circuits. Plasma oxidation has been performed at room temperature with oxide quality comparable to that of thermal oxide. This high quality oxide has been applied to the fabrication of SiGe metal insulator semiconductor field effect transistors. Bilayer resist has been etched with high etch rate ($\sim$1 $\mu$m/min) and high selectivity ($>$200:1). Vertical profile and smooth morphology were obtained for features that were 0.1 $\mu$m wide and 1 $\mu$m deep. Etching of Si has been studied and used to pattern 0.35 $\mu$m polysilicon gates with a two-step etch process. Etch-induced damage has been evaluated by electrical characterization and surface analysis. Surface damage is found to be minimized by using low ion energy and high reactive species concentrations. A damage model is proposed to relate the generation of defects to the etch conditions. These advanced plasma technologies are important for the fabrication of future generations ULSI circuits.