Plastic deformation magnetic assembly of out-of-plane structures using vapour phase hydrofluoric (HF) acid release

We report on the fabrication of out-of-plane microstructures using plastic deformation magnetic assembly (PDMA) and vapour phase HF release process. A 0.5 μm thin silicon oxide (SiO2) layer deposited on blank silicon has been implemented as a sacrificial layer. A nickel film, 0.5 μm thick, deposited on top of the SiO2 layer acts as the seed layer for the electrodeposition of a 4 μm nickel–iron permalloy film. The surface morphology and chemical composition of the permalloy film has been characterised using scanning electron microscopy and X-ray photoelectron spectroscopy (XPS), respectively. A dry vapour phase hydrofluoric (HF) acid release step has been employed to etch the sacrificial SiO2, producing out-of-plane microstructures with high yield in the absence of a post-release drying step.