Micromachining Using EVAM (Elliptical Vibration Assisted Machining)

Abstract

The goal of this research is to demonstrate Elliptical Vibration Assisted Machining (EVAM) as a multi-level planar microstructuring tool for MEMS applications. While many MEMS (Micro Electro Mechanical Systems) devices are fabricated using silicon etching techniques developed for the microelectronics industry, micromachining is an attractive alternative because of its low start-up cost, applicability to a wide range of materials, high flexibility of feature geometry, and low prototyping cost. Vibration assisted diamond turning is proposed as an alternative method of fabricating 3D MEMS devices. To demonstrate the capabilities of this technique, a diamond tool holder that moves in an elliptical path at 1000 Hz (the Ultramill) was attached to a 3-axis diamond turning machine (DTM). Using this system, structured surfaces with high accuracy and surface finish were created. Multi-level structures with 15 μm plan-view features, 500 nm elevation features, and 20 nm RMS surface finish have been achieved on a 200 micrometer part scale. In addition, the limits of the fabrication technique in its current form were identified by machining specific features and relating them to the tool, the process and the DTM. Limitations of the current process include a sub-Hertz drift error in the air-bearing third axis, temperature control of the Ultramill, and natural frequencies of the DTM axes in the range of measured error frequencies in machined parts.