Magnetolithography

Magnetolithography (ML) is a method for pattern surfaces. ML based on applying a magnetic field on the substrate using paramagnetic metal masks named "magnetic mask". Magnetic masks are analogous to a photomask in photolithography, in that they define the spatial distribution and shape of the applied magnetic field. The second component of the process is ferromagnetic nanoparticles (analogous to the photoresist in photolithography) that are assembled onto the substrate according to the field induced by the magnetic mask.

ML can be used for applying either a positive or negative approach. In the positive approach, the magnetic nanoparticles react chemically or interact via chemical recognition with the substrate. Hence, the magnetic nanoparticles are immobilized at selected locations, where the mask induces a magnetic field, resulting in a patterned substrate. In the negative approach, the magnetic nanoparticles are inert to the substrate. Hence, once they pattern the substrate, they block their binding site on the substrate from reacting with another reacting agent. After the adsorption of the reacting agent, the nanoparticles are removed, resulting in a negatively patterned substrate.

ML is a backside lithography, which has the advantage of ease in producing multilayer with high accuracy of alignment and with the same efficiency for all layers.