Surface micromachined thermally driven micropump

This paper presents the design, fabrication, and testing of a thermally driven micropump fabricated by surface micromachining. The micropump consists of a membrane of a corrugated diaphragm, a sealed cavity filled with air and buried with n⁺ polysilicon microheater and a microchannel with a pair of nozzle and diffuser valves. The polysilicon membrane was used as a structural layer and low-temperature oxide (LTO) and plasma enhanced chemical vapor deposition (PECVD) oxide as a sacrificial layer. Using gas-phase etching (GPE) process with anhydrous hydrogen fluoride (HF) gas and isopropyl alcohol (IPA) vapor, we successfully fabricated the thermally driven micropmump with no virtually process-induced stiction. The flow rate of the micropump is measured at the applied voltage of 25V with the duty cycle of 50%. The maximum flow rate of the micropump with the corrugated diaphragm is about 3.1μl/min at 5Hz.