Knudsen pump based on silicon etching and thermal oxidation process for on-chip vacuum pumping

This work reports the fabrication and evaluation of Knudsen pump for on-chip vacuum pumping. Three AFM (atomic force microscope) cantilevers are integrated into small chambers with a size of 5 mm × 3 mm × 0.4 mm for the pump's evaluation. Knudsen pump is fabricated using deep RIE (reactive ion etching), wet thermal oxidation and anodic bonding processes. The fabricated device is evaluated, which based on monitoring the quality (Q) factor of the integrated cantilevers. The Q factor of the cantilever is increased from 300 to 1150 in cases without and with a temperature difference approximately 25°C between the top (hot side at 40°C) and bottom (cool side at 15°C) sides of the fabricated device, respectively. The evacuated pressure chamber of around 10 kPa is estimated by the Q factor of the integrated cantilevers.