Automatic film formation system for ultra-thin organic/inorganic hetero-structure by mass-controlled layer-by-layer sequential adsorption method with ‘nm’ scale accuracy

A mass-controlled layer-by-layer sequential adsorption process was newly developed for the fabrication of ultra-thin organic films formed by various polymers, monomers, and inorganic materials. This technique can be applied to both water solutions and volatile solvents. In this process, a quartz crystal microbalance (QCM) was attached to the arm of a robot and the frequency shifts during the adsorption of the materials were monitored. By feeding back the data acquired by the QCM from the deposition to the dipping time, a high quality self-assembly film was produced. As a result, the layer thickness of the films can be controlled with nm-order accuracy. The cross-sectional transmission electron microscopy (TEM) observation of the films formed by the conventional time controlled dipping method and the newly established mass-controlled dipping method reveals that the interface of the hetero structure of the latter was much smoother than the former. The remarkable advantage of the mass-controlled dipping method was also proved by in-situ observation of the adsorption process of the polyelectrolytes in solution using an atomic force microscopy.