US Patent 7615164 Plasma etching methods and contact opening forming methods

The invention includes etching and contact opening forming methods. In one implementation, a plasma etching method includes providing a bottom powered plasma chamber that includes a plasma generating electrode powerable at different first and second frequencies, with the first frequency being lower than the second frequency. A substrate is positioned over the electrode. A plasma is generated over the substrate with the electrode from a first applied power at the first frequency and a second applied power at the second frequency. A ratio of the first applied power to the second applied power is from 0 to 0.25 or at least 6.0. Material is etched from the substrate with the plasma.