A die-scale micromachining process for bulk PZT and its application to in-plane actuators

Bulk ceramics (including PZT) are important materials for electronic and microsystem packaging or device applications, but they are usually difficult to pattern lithographically. A fabrication process combining lithography, electroplating, batch mode micro electro-discharge machining (μEDM) and batch mode micro ultrasonic machining (μUSM), LEEDUS, has been developed to provide die-scale pattern transfer capability from lithographic masks onto ceramics, glass or other brittle materials. A related process (SEDUS) uses serial μEDM and omits lithography. Feature sizes of 25 μm have been micromachined on the glass-mica (Macor™) ceramic plate with a 4.5×4.5 mm² die size, 34 μm cutting depth, and 18 μm/min machining rate. As a demonstration an octagonal spiral shaped in-plane actuator was fabricated from bulk PZT using this process. A device of 20 μm thickness and 450 μm × 420 μm footprint produces a displacement of ∼2 μm at 40 V.