Micro-pyramidal structure fabrication on polydimethylsiloxane (PDMS) by Si (100) KOH wet etching

Abstract

A high degree of accuracy in bulk micromachining is essential to fabricate micro-electro-mechanical systems (MEMS) devices. A series of etching experiments is carried out using 40 wt% KOH solutions at the constant temperature of 70 °C. Before wet etching, SF₆ and O₂ are used as the dry etching gas to etch the masking layers of a 100 nm thick Si₃N₄ and SiO₂, respectively. The experimental results indicate that (100) silicon wafer form the pyramidal structures with (111) single crystal planes. All the etch profiles are analyzed using Scanning Electron Microscope (SEM) and the wet etch rates depend on the opening sizes. The manufactured pyramidal structures are used as the pattern of silicon mold. After a short hardening of coated polydimethylsiloxane (PDMS) layer, micro pyramidal structures are easily transferred to PDMS layer.