Supersonic Cluster Beam Deposition

PMCS-SCBD technique consists in the fabrication of cluster molecules in the source supported by an inert carrier gas that, expanding through a series of vacuum chambers, form a supersonic cluster-seeded beam. Thin films can be assembled starting from cluster molecules with a bottom-up approach, simply intercepting the beam with a substrate. Substrate controlled movement (rastering) is used to get a uniform coverage over typical areas of few square centimeters.The main characteristics of this technique are:
  • large presence of molecular clusters in the film - SCBD is a low kinetic energy process so that the cluster particles keep their original structure once they impinge on the substrate
  • complete freedom of choice of the support substrate – clusters deposition is a room temperature, neutrally charged process thus imposing no limitations to the substrate nature
  • large variety of cluster species – in principle PMCS can work with any solid conductive or semi-conductive material and composites or mixtures of them; also non-conductive species can be introduced in the source in solid or liquid phase through the carrier gas
  • high purity films – the separation of cluster formation and cluster deposition steps allows the use of differential pumping to take off the process all unreacted species
  • micro/nano patterning – through aerodynamic manipulation the supersonic cluster beam can be collimated to replicate stencil mask patterns down to the nano-scale

The materials produced are in general extremely porous (high surface to volume ratio), have medium/low density and are quite soft. The average size of the clusters can be tuned in order to design the film morphology. The resulting films are particularly adapt to applications where the interface properties at the micro/nano scale are crucial.

Referent: Claudio Piazzoni

Participants: Paolo Piseri, Paolo Milani