Design freedom in multilayer thin-film devices

In fabricating inorganic thin-film devices, the relative etch rates of materials in a given etch chemistry often limit the obtainable multilayer structures. Alternatively, in fabricating multilayer organic devices by solution processing, the ability to formulate the active organic materials in orthogonal solvent systems is limiting. The pattered-by-printing method uses the combination of selective area deposition (SAD) and atomic layer deposition (ALD) to form high-quality metal oxide thin-film devices. We print an inhibiting polymer ink that patterns the functional inorganic materials that are deposited via spatial ALD (SALD). The process is inherently orthogonal, as the polymer ink does not etch or swell the inorganic functional layers. Each functional layer is additively patterned as deposited, with device isolation and vias defined by the printed inhibitor. The combination of process orthogonality and additive patterning removes processing-related constraints on device design, and readily allows for any combination of bottom- and top-gate thin-film transistor architectures to be formed on the same substrate. The freedom of this approach is further demonstrated by both all-enhancement-mode circuits and enhancement-depletion-mode circuits. In addition, we present a new tool to tune circuit performance by local control of dielectric thickness.