Paper PS1-TuA1
Feature Profile Evolution for HARC Etching in SiO₂

Tuesday, November 1, 2011, 2:00 pm, Room 202

Feature profile control for HARC etching is a very important issue. Possible profile defects such as bowing, necking, variations in depth and shape, among others, become critical for the next technological steps with ever shrinking dimensions of the features. Using numerical simulations as a tool, we studied HARC etching of SiO2 by the fluorocarbon-argon-oxygen plasma in a capacitive-type plasma system. The first step in our simulations involved estimation of neutral and ion fluxes, and their angle-energy distributions for most important species involved into processing in the systems chosen for comparison. Then the feature profile simulator FPS-3D [1] was run to estimate various chemical and physical effects on HARC profile evolution during processing. The difficult part in those simulations was taking into account deposition of polymer films and etching through those films. The final results come as a competition between counteracting effects of etching and deposition. Important effects of ions for etching at the bottom of the contact holes, and of polymer films for protecting sidewalls from further etching, were investigated. Possible bowing and necking effects were considered in detail. Calculations were carried out for different sizes of the features, different gas compositions, and different RF powers leading to different ion energies. Published data for the underlined reaction mechanisms were analyzed and used for tuning the chemical reactions database in the FPS-3D code. Comparison of simulations with different experiments and the corresponding analysis of HARC etch processing are presented. The authors are thankful to Masanobu Honda and Akira Tanabe for providing experimental data.

[1] P. Moroz, 57^th AVS Int. Symp., PS1-ThA10, Albuquerque, NM, October, 2010.