A Si-based suspended tunnel structure with trapezoidal section by two-step etching

Abstract

Two - step etching method is used to prepare Si-based suspended tunnel structure with trapezoidal section. In the first wet etching, surfactant Triton-X-100 is added to TMAH enchant to inhibit crystal plane characteristics. Bulk Si Rib with trapezoidal cross section is formed, with inclination of side and height being modulated by changing etching time, so as to obtain good stability. After SiO2 support layer is grown by thermal oxidation, pure 25%TMAH is used in the second wet etching to quickly lateral etch and undercut the bulk silicon under the support layer and form a suspended structure along <100> opening. Using additive-no additive two-step etching method, suspended structure with high stability and compressive strength, good insulation characteristics, high yield can be prepared. It lays a solid foundation for the development of high sensitivity photo, thermal, chemical and gas sensors.