Sub-30nm alignment accuracy between layered photonic nanostructures using optimized nanomagnet arrays

We present experimental results indicating fine alignment of stacked nanopatterned silicon nitride membranes to better than 30 nm. The initial coarse alignment via membrane folding was 2 mum, which gives a coarse-to-fine alignment improvement of more than 60times. Alignment was achieved by using the attractive force between arrays of nanomagnets patterned on the membranes before folding. Optical gratings and circular voids forming a 3D photonic crystal-like structure were patterned before membrane release and self-aligned after folding. Alignment performance was maintained during multiple folding and unfolding operations.