Investigation of sacrificial layer masking fabrication of dual-frequency quartz crystal microbalance

To solve temperature compensation problems and eliminate environmental impact factors for quartz crystal resonators, a study on one-chip inverted mesa multi-channel/frequency quartz crystal microbalance (MQCM) was presented. MQCM was fabricated by a simple, precision controlled and plasma-ion-beam etching technique. The research intention was devoted to etching nanometer-scale depth inverted mesa of a quartz wafer using aluminum (Al) as a sacrificial layer. The masking method was demonstrated with 0.497 mA/cm2 ion-beam density, 300 eV argon-ion energy and 1.0 μm/h etching rate. Both morphology of etched surface and its depth were characterized by laser scanning confocal microscope (LSCM). Resonant frequencies of a fabricated MQCM indicated that the thinning approach demonstrated will fine tune relevant QCM resonant frequency as proposed. The one-chip dual-QCM in the case of 3.28 μm depth etching would result in its fundamental resonance peak shifted at 0.5054 MHz. The inverted mesa etched at micron level significantly will provide fine-tunable frequencies on one-chip monolithic device fabricated. The simple adhesion-type Al sacrificial layer masking method and plasma etching technique do have great potential for precise micro-nano scale structure fabrications.