A Study on High Resolution Batch-Mode Micro-Utralsonic-Machining with Constant Feed Force of Sapphire for MEMS Application

Sapphire has widely used for application to MEMS due to its excellent optical property, mechanical property, chemical stability, high melting point and electrical insulation property, such as X-ray resonator cavities, optical wall shear stress sensor for high temperature applications, lateral overtone bulk acoustic resonator with high f-Q and increasing the output power of LED. This paper presented a high resolution batch-mode micro-utralsonic-machining (μUSM) with constant feed force of sapphire for MEMS application, and it has advantages of high machining efficiency, resolution and surface quality compared to other machining method. High aspect ratio (>4) structure with the feature resolution below 1μm of sapphire has been machined by batch-mode μUSM. A machining depth of 40μm has been achieved at a removal rate up-to 4μm/min, and its bottom surface roughness is below Ra 80nm.