Electropolishing as a method for deburring high aspect ratio nickel RF MEMS

High aspect ratio nickel radio frequency microelectromechanical systems (RF MEMS) were fabricated by X-ray lithography and electroplating. Control of growth during electroforming of micro components is in general a problem in terms of achieving homogeneous thickness due to a non-uniform current distribution across a layout. It is necessary to level the deposited layer by means of a lapping process which results in burr formation. To ensure the functional properties of the devices these burrs have to be removed. Electropolishing with a current density of 80 A/dm² is used for burr removal from nickel micro components containing small width (~10 μm) structural elements. The investigated metal removal rates range from 0.2 to 1.8 μm/s depending on burr formation, presence or absence of resist and device position in the layout during electropolishing. Furthermore, edge rounding, a common electropolishing effect, is only observed when electropolishing in the absence of resist.