SPTS APS - A system for Reactive Ion Etching consisting of a load lock for 200mm diameter wafers and a process chamber for anisotropic etching of silicon oxide, silicon nitride, polysilicon, and other materials such as amorphous Si, using a plasma source and fluorine chemistry. The process chamber is of metallic construction and is heated to reduce the level of deposition on it. The system has an optimised geometry to improve plasma confinement, which further increases the plasma density above the wafer and also hinders undesirable deposition inside the chamber.