The Surface Technology (STS) Advanced Oxide Etch (AOETM) ICP etch system is capable of high rate etching of dielectric materials.  The mechanism for etching SiO2 in the AOE source is based on the continuous deposition of a thin layer of CxFy polymer on the surface of the wafer, which at the same time is bombarded by heavy ions to generate a reaction between the deposited layer and the SiO2.  The heavy ions break the bonds both within the CxFy layer, as well as the bonds between the silicon and oxygen leading to the formation of a volatile reaction product (SiF4) that is desorbed from the surface.  Profile control is achieved through a combination of an RF bias applied to the substrate platen, that causes the ions to bombard the base of the trench more than the sidewalls of the feature, and the use of low chamber pressure to reduce scattering.