Techniques for micromachining multilayered structures in silicon

The effects of wet anisotropic etching of [100] silicon were studied with mask edges aligned at 45/spl deg/ to the primary wafer. Samples were etched in aqueous KOH solution with the addition of isopropyl alcohol (IPA). The addition of IPA caused a change from the formation of vertical {100} walls to sloping {110} walls only for solutions below a critical concentration and temperature. The dependence on concentration was then applied to produce a new multilayer structure with {110} walls fabricated on top of {100} walls.