Effects of etching pressure and aperture width on Si etching with XeF2 [for MEMS]

We developed a XeF₂ pulse etching system controlled by a computer and examined effects of etching pressure and an aperture width on Si etching. The etching depth and the undercut ranged from 12.9 to 17.6 μm and 7.5 to 13.0 μm as the aperture width increases with a charge pressure of 390 Pa, a pulse number of 10, a pulse duration time of 60 seconds, respectively. Etching depth and undercut ranged from 11.8 to 14.2 μm and 9.1 to 10.4 μm as the aperture width increases with the charge pressure of 65 Pa, 50 pulses, 60 seconds, respectively The aperture effects decreased with decreasing the etching pressure. Etching roughness decreases with decreasing the etching pressure. The roughness was 1150 Å with the charge pressure of 390 Pa, 10 pulses, 60 seconds and 250 Å with the charge pressure of 65 Pa, 50 pulses, 60 seconds