Nanobridge Stencil Enabling High Resolution Arbitrarily Shaped Metallic Thin Films on Various Substrates

Abstract

Stencil lithography (SL), which uses a perforated membrane as a reusable shadow mask to locally add material patterns on substrates provides a simple but versatile approach for the fabrication of functional devices on a large variety of substrate materials by physical vapor deposition (PVD). Mechanical stress induced by the accumulation of condensed material on the thin stencil membrane during the PVD step leads to stencil bending and breaking, therefore, suspended stencil membranes with arbitrary openings are, in practice, not possible. Here, a new approach to remedy this limitation is reported by introducing auxiliary bridges in stencils. These bridges prevent the suspended membrane from bending out of plane, thereby enabling aperture openings to have almost arbitrary geometry. These bridges are sufficiently narrow so that they do not entirely block the material deposition by PVD and thus create a continuous material pattern by taking advantage of the blurring effect. The successful metal deposition through the designed nanobridge stencil on a wide range of substrate materials underlines the usability and the versatility of the proposed stencil design. The work presented here provides a versatile fabrication method to produce arbitrarily shaped metal patterns that were previously impossible due to the topological constraints of nanostencils.