A wide variety of materials, liquid and particulate, in various sizes and shapes have been deposited using this technique for various applications; there are some 40 recipes for coating different materials.
Potential applications have ranged in “Printed” Electronics, to include flexible Thin Film Solar and Solid State Lighting which require deposition of expensive material (Semiconducting Inks, OLED chemistries, etc.) in ultra-thin, ultra-uniform layers, as well as new forms of transparent conductors such as silver nanorod meshes, graphene flakes and other applications…
The process is ideally suited for monolayers; no other known process is as fast or effective. A wide variety of applications have been explored, as in the following representative examples:
Uniform, ordered layers of deagglomerated, nano-porous 500 nm Ti02 particles were deposited on an aluminized plastic film roll in a 30 cm web based tool at speeds to 1.2 m/min. A variety of materials are further being tried for several thin film battery concepts.
A multi-pass, 3 layer-by-layer stack of 5 nm Gold particles was demonstrated for texturing of Poly-Si wafers as reflective or AR coatings, or texturing for SSL apps, or a method for realizing photonic crystals or for LBL assembly:
Finally, the process is a ready, fluidic means of rapidly assembling not only particles, but other structures such as micro-die, silicon slivers, and the like … a number of applications are being explored:
Polymer Thin Films
Ultra-thin, ultra-uniform polymer films are readily achieved. The natural properties of the gas-liquid interface: flatness, mobility and tension, together with gravity hydrodynamically drive the material at the interface toward and onto a film formation line, while the solvent fades from the gas-liquid interface through evaporation and immersion. The pressure applied onto the film’s long axis is kept constant while the film is transferred from the liquid surface toward a solid substrate.
Thinness under 5 nm has been achieved with PMMA, with no pin holes or defects. Detected defects are primarily from environmental particles and not from surface or resist particles.
We have shown a broad range of typical photoresists at 20 nm and to 1 nm, suggesting applications for EUV photolithography. For example, common photoresists and polymers for I-line, DUV and E-beam lithography have been shown, to include SP1813, UV1400, AZ9260, NED, ZEP, and PMMA:
Ultra-thin coatings are highly conformal; shown below are magnified details of a 10 µm coating of AZ9260 showing conformability across a 15 µm step, as well as the significantly smaller edge bead realized with this technique, when compared to traditional spin coating:
Thicker Films - Suspended Membranes
A unique mode enables many polymer materials of a certain thickness (typically >500 nm) to form a suspended membrane across the topography, the opposite of conformal, acting as a planarization layer or even a releasable membrane for a bond/ debond method in flex electronics: