SURFACE SMOOTHING OF DIAMOND MEMBRANES BY REACTIVE ION ETCHING PROCESS

This paper describes a procedure based on reactive ion etching develop ed to reduce the surface roughness of CVD diamond thin films. The tech nique involves etching a bilayer made up of diamond and a planarizing SiO2 layer in an SF6-O-2 plasma mixture. Etching conditions have been determined which yield equal rates for both diamond and the SiO2 cover layer and favour the removal of diamond peaks. Smoothed surfaces have been characterized by SEM, AFM and XPS: the results exhibit a signific ant decrease in roughness. This novel technique offers promising prosp ects for polishing thin diamond membranes for X-ray lithography applic ations without the removal of significant amounts of diamond material. The optical transmittance of diamond membranes, mainly affected by li ght scattering due to surface roughness, is significantly improved usi ng this method of planarization.