Development of a Deep Silicon Phase Fresnel Lens Using Grayscale Lithography and Deep Reactive Ion Etching

dc.contributor.advisorGhodssi, Professor Rezaen_US
dc.contributor.authorMorgan, Brian C.en_US
dc.description.abstractA phase Fresnel lens (PFL) could achieve higher sensitivity and angular resolution in astronomical observations than the current generation of gamma and hard x-ray instruments. For ground tests of a PFL system, silicon lenses must be fabricated on the micro-scale with controlled profiles to enable high lens efficiency. Thus, two MEMS-based technologies, gray-scale lithography and deep reactive ion etching (DRIE), are extended to create multiple controlled step heights in silicon on the necessary scale. A Gaussian approximation is introduced as a method of predicting a photoresist gray level height given the amount of transmitted light through a gray-scale optical mask. Etch selectivity during DRIE is then accurately controlled by introducing an oxygen-only step to a standard Bosch cycle to produce the desired scaling factor between the photoresist and silicon profiles. Finally, a profile evaluation method is developed to calculate the expected efficiency of measured silicon profiles. Calculated efficiencies above 87% have been achieved.en_US
dc.format.extent2325073 bytes
dc.relation.ispartofseriesISR; MS 2004-3en_US
dc.titleDevelopment of a Deep Silicon Phase Fresnel Lens Using Grayscale Lithography and Deep Reactive Ion Etchingen_US


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