Silicon Trench Etching Using a Mixture of a Fluorocarbon, Oxygen and Nitrogen
Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
A method has been proposed to avoid the deposition of SiO2 on trench sidewalls which results when a mixture of a fluorocarbon and oxygen is used for etching. The proposal provides for the addition of N2 to the etching gas mixture. In semiconductor processing silicon trench etching is accomplished by using mixtures of a chlorinated fluorocarbon, such as CClF3, and O2 . This provides directional etching of silicon with high etch selectively of Si to SiO2 . This process, however, results in an SiO2 deposition on the sidewall resulting in an unacceptable trench profile. Under normal processing, such a material is removed using a buffered HF solution. This, however, may result in undesirable lateral etching of other SiO2 layers.