Fabricating a World with DLP

BPL is a cantilever-free scanning probe lithography technique that stems from Polymer Pen Lithography (PPL). Cantilever-based scanning probe lithography techniques, such as Dip-Pen Nanolithography (DPN), have shown great promise for patterning a wide range of materials onto a surface with nanoscale resolution. However, the serial mode of writing and inability to scale the cantilever architecture in a feasible manner, has limited the widespread adoption of these techniques. Rather than using multiple cantilevers with a single pen tip via DPN, PPL uses a two-dimensional elastomeric tip array mounted on a transparent substrate. By effectively eliminating the cantilever and allowing for as many as 11,000,000 pens per array, PPL greatly improves the overall speed and patterning capabilities for scanning probe lithography tools.

BPL is a recently invented photo-lithography technique that is commonly used to fabricate nanoscale components in applications such as electronics, biology, medicine, and chemical synthesis. For BPL, the elastomeric tip array employed in PPL is coated with a thin layer of metallic gold and then nanoscopic apertures are physically or chemically generated at the apex of the tips. Rather than directly printing inks onto a surface with the pen tips like in PPL, BPL directs light through those apertures to expose the underlying photosensitive materials. Importantly, the resolution of this technique is tied to the size of the apertures – the smaller the apertures the finer the structures they can create – and for small enough apertures, this technique ultimately creates nanoscale features with dimensions below the diffraction limit of the light source. Although the use of light in tandem with a BPL array allows for users to perform a multitude of highly localized photoreactions in parallel, this strategy is unable to yield arbitrary patterns over large areas necessary for many photochemical applications because each tip in the array writes the same pattern.