Vapor HF sacrificial etching for phosphorus doped polycrystalline silicon membrane structures

In this work we present a technique using HF vapor to release phosphorus doped polycrystalline silicon (Phos-Poly) circular membrane structures. A 2 um thick annealed phosphosilicate glass (PSG) has been used as the sacrificial layer. The sacrificial etching was followed by solvent rinses and Critical Point Drying (CPD) to remove any residual HF and to avoid sticition. A Phos-Poly diaphragm with a diameter of 106 um has been successfully released as well as some membrane arrays. This technique has been proved very simple and effective. The membrane structures can be used in pressure sensing applications.