Patent ID: 7255803

Claim:
A method of forming contact openings comprising: providing a bottom powered plasma chamber comprising a plasma generating electrode powerable at different first and second frequencies, the first frequency being lower than the second frequency; positioning a substrate over the electrode, the substrate comprising an insulative layer comprising silicon dioxide over conductive or semiconductive material, the insulative layer having an outermost portion and having an innermost portion proximate the conductive or semiconductive material, the outermost portion having a thickness which is at least five times that of the inner portion, the substrate comprising a patterned masking layer having openings therein for defining contact openings; and forming contact openings through the insulative layer to the conductive or semiconductive material using the patterned masking layer within the chamber, the forming comprising: removing the outermost portion effective to expose the innermost portion; after exposing the innermost portion, plasma etching the innermost portion effective to expose the conductive or semiconductive material with a plasma generated with the electrode from a first applied power at the first frequency and second applied power at the second frequency, a ratio of the first applied power to the second applied power being from greater than 0 to 0.25 or at least 6.0; and the removing comprising plasma etching with a plasma generated with the electrode from a third applied power at the first frequency and a fourth applied power at the second frequency a ratio of the third applied power to the fourth applied power being from 0.26 to 5.9 within the chamber, the forming of contact openings resulting in increased field threshold voltage than would otherwise occur under identical conditions except if plasma etching the innermost portion were conducted using a ratio of the first applied power to the second applied power from 0.26 to 5.9.