Two-dimensional microscanner actuated by PZT thin film

This paper introduces the fabrication and characterization of 2D resonant microscanners actuated by sol-gel deposited PZT thin films. The piezoelectric PZT thin films with silicon micromachining technology provide the advantages of high scanning frequencies and low driving voltages. The actuation principle is based on the bimorph beam structure, which consists of an oxide layer and a piezoelectric PZT layer. The 2D scanning performance can be achieved by applying AC voltages with phase shifts at resonance frequencies to the actuating beams. The devices were fabricated through thin film depositions, lithography, dry plasma etching and ICP releasing process. The fabrication processes were improved considerably. A STS ICP system was used instead of KOH or other wet-chemical etching processes to prevent the damages of front side devices while the sample was etched through. For a scanner structure with a 300 X 300 micrometers 2 mirror plate, the first four resonance frequencies were measured to be in the range of 10-30 kHz. To investigate the vibration modes, the deflections on different locations of the mirror plate were measured. The 2D scanning angles were determined to be 8 degrees at 16.2 kHz in one direction and 11 degrees at 23.4 kHz in the perpendicular direction.