A method for fabricating substrate material to include trenches and unreleased beams with submicron dimensions includes etching a first oxide layer on the substrate to define a first set of voids in the first oxide layer to expose the substrate. A second oxide layer is accreted to the first oxide layer to narrow the first set of voids to become a second set of voids on the substrate. A polysilicon layer is deposited over the second oxide layer, the first oxide layer and the substrate. A third set of voids is etched into the polysilicon layer. Further etching widens the third set of voids to define a fourth set of voids to expose the first oxide layer and the substrate. The first oxide layer and the substrate is deeply etched to define beams and trenches in the substrate.