REACTIVE ION ETCHING OF SILICON SUBMICRON-SIZED TRENCHES IN SF6 C2CL3F3 PLASMA/

Reactive ion etching (RIE) of silicon with thin AZ 1350 and PMMA etch masks in SF6/C2Cl3F3 plasma is studied. Anisotropic selective etching of silicon with PMMA mask is found. RIE of submicron-sized trenches in to silicon with AZ and PMMA masks is investigated under etch condition s typical for high anisotropy. It is shown, that etch rate and etched profile of trenches depend on aspect ratio. Highly anisotropic etching of silicon submicron-sized trenches with selectivity of silicon to PM MA mask of about 10 is developed and used for the fabrication of silic on phase Bragg-Fresnel lenses for hard x-rays.