Plasma dry etched p-silicon micromolds for permalloy microstructure array electrodeposition

In this paper we present a new process to fabricate permalloy microstructures by plasma etching micromold on p-silicon and then electrochemically filling the micromold obtained. The square trenches with 100 μm lateral size are firstly drilled onto a patterned wafer by a plasma process with CF4 and SF6 mixtures as etchant gases. A trench depth of 18 μm can be realized in 10 min. To realize charge transfer between electrode and electrolyte, boron atoms are selectively diffused to the bottom of the trenches by a hot process to form a thin p++ Si layer. A special clamp is designed to handle the wafer, which allows to apply a DC plating current from the wafer rear and to get uniform metallic structure heights. High permeability (1700) FeNi permalloy microstructures has been successfully obtained by this process.