High resolution micro ultrasonic machining (HR-μUSM) for post-fabrication trimming of fused silica 3-D microstructures

This paper presents the design and characterization of a high resolution micro ultrasonic machining (HR-μUSM) process suitable for post-fabrication trimming of 3-D microstructures made from fused silica and other materials. The process targets low machining rates, high resolution, and high surface quality. On flat fused silica substrates, the process achieves machining rates ≤10 nm/sec averaged over 1 minute. The average surface roughness (S_a) achieved is ≤30 nm. The process is successfully demonstrated for trimming hemispherical 3-D microstructures made from fused silica.