Fabricating HARMS by using megasonic assisted electroforming

Abstract

Electroforming is a main fabrication method to produce metal microstructures for microelectromechanical systems. Since the mass transport is limited in high aspect ratio microstructures (HARMS), problems such as uneven filling and void formation are often involved in the electroplating of deep molds. In this work, megasonic agitation is employed to improve the electroplating of HARMS, which causes little damage to the resist structure and is thereby advantageous over ultrasonic agitation. Cantilever beams and gaps with a linewidth of 10 lm and an aspect ratio of 25 have been obtained. The main effects of megasonic agitation are analyzed. The results indicate that resonant bubbles in the electrolyte are probably responsible for the mass transport enhancement during the electroforming process.

Electroplating for high aspect ratio vias in PCB manufacturing: enhancement capabilities of acoustic streaming

“…For trenches, AS inside the via has no major influence, which follows from both theoretical considerations regarding AS in narrow closed channels with a reflective bottom and real-life experiments, e.g., [14].…”

Fabrication of metal microfluidic chip mold with coplanar auxiliary cathode in the electroforming process

“…For further improvement, the ultrasonic agitation is used in the micro electroforming and is an effective way to improve the thickness uniformity [19,20]. But for longtime electroforming, the high temperature and pressure caused by ultrasonic cavitation may destroy the photoresist structures [21], which limits the application of ultrasonic electroforming to a certain extent. Because electric field distribution directly determines the thickness uniformity of micro electroforming, the methods of optimizing electric field distribution, such as auxiliary cathode [13,[22][23][24] and insulating shield [25] have been developed.…”