L M Doeswijk

Nanostenciling for fabrication and interconnection of nanopatterns and microelectrodes

Stencil lithography is used for patterning and connecting nanostructures with metallic microelectrodes in ultrahigh vacuum. Microelectrodes are fabricated by static stencil deposition through a thin silicon nitride membrane. Arbitrary nanoscale patterns are then deposited at a predefined position relative to the microelectrodes, using as a movable stencil mask an atomic force microscopy (AFM) cantilever in which apertures have been drilled by focused ion beam. Large scale AFM imaging, combined with the use of a high precision positioning table, allows inspecting the microelectrodes and positioning the nanoscale pattern with accuracy better than 100nm.

In-situ stabilization of membranes for improved large-area and high-density nanostencil lithography

We present a MEMS process to fabricate aperture independent stabilization of silicon nitride membranes to be used as miniature shadow masks or (nano) stencils. Large-area thin-film solid-state membranes were fabricated with silicon nitride corrugated support structures integrated into the stencil. These corrugated support structures are aimed to reduce the membrane deformation due to the deposition induced stress and thus to improve the dimensional control of the deposited patterns. We have performed physical vapor deposition (PVD) of Cr on unstabilized i.e. standard stencil membranes and stabilized stencil membranes. The structures were also modeled using commercial FEM tools. The simulation and experimental results confirm that introducing stabilization structures in the membrane can significantly reduce out-of-plane deformations of the membrane. The results of this study can be applied as a guideline for the design and fabrication of mechanically stable, complex stencil membranes.