"MELODE" Membrane for local Deposition

Patterning with lithographic processes requires processing steps including the use of resist spinning and chemical solvents for the development of resist. These steps cannot be applied to mechanical fragile and bio/chemically functional surface layers such as organic thin film and Self Assembled Monolayer (SAM). There is however a need for the creation of surface patterns without lithography steps, especially in the field of bio-chemical micro-systems, MEMS, molecular electronic devices, etc. In the framework of the TOP NANO 21 project "MELODE" we developed a simple but powerful new method, using a micro/nano shadow-mask or stencil. Evaporation through the shadow-mask which is in well-defined proximity or in contact with the surface, directly deposits a controlled amount of material only and exactly at the locations where it is needed, hence making further processing steps totally obsolete. The shadow evaporation technique uses an ultra-thin mechanical solid-state membrane of silicon nitride with apertures. In the past solid-state membranes made by silicon nitride (SiN) have been used for the patterning in the 100 nm lenght scale structures within a limited area of a few 10s square-um. This limitation was given by the low stability of the freestanding membrane to sustain the mechanical stress induced by the deposited layer. To overcome this limitation we present here advances towards a full-wafer (100 mm) MEMS based nanostencil to allow high-throughput, large area micro & nano-patterning, by incorporating local mechanical reinforcement or support structures.