Rolled‐up nanotechnology has received significant attention to self‐assemble planar nanomembranes into 3D micro and nanotubular architectures. These tubular structures have been well recognized as novel building blocks in a variety of applications ranging from microelectronics and nanophotonics to microbatteries and microrobotics. However, fabrication of multiwinding microtubes with precise control over the winding interfaces, which is crucial for many complex applications, is not easy to achieve by existing materials and technologies. Here, a dry rolling approach is introduced to tackle this challenge and create tight windings in compact and highly symmetric cylindrical microstructures. This technique exploits hydrophobicity of fluorocarbon polymers and the thermal expansion mismatch of polymers and inorganic films upon thermal treatment. Quality parameters for rolled‐up microtubes, against which different fabrication technologies can be benchmarked are defined. The technique offers to fabricate long freestanding multiwinding microtubes as well as hierarchical architectures incorporating rolled‐up wrinkled nanomembranes. This work presents an important step forward toward the fabrication of more complex but well‐controlled microtubes for advanced high‐quality device architectures.
Monolithic integration of microscale organic field-effect transistors (micro-OFETs) is the only and inevitable path toward low-cost large-area electronics and displays. However, to date, such an ultimate technology has not yet evolved due to challenges in positioning and patterning highly crystalline microscale molecular layers as well as in developing micrometer scale integration schemes. In this work, by mastering the local growth of molecular semiconductors on pre-defined terraces, single-crystal quasi-2D molecular layers tens of square micrometers in size are created in dense periodic arrays on a Si substrate. Nondestructive photolithographic processes are developed to pattern micro-OFETs with mobilities up to 34.6 cm 2 V −1 s −1 . This work demonstrates the feasibility to integrate arrays of short-channel micro-OFETs into electronic circuitry by highly parallel and size scalable fabrication technologies.
A simple method to fabricate flexible, mechanically robust, and reusable SU‐8 shadow masks is demonstrated. This shadow mask technology has high pattern flexibility as various shapes with different dimensions can be created. The fabricated shadow masks are characterized in terms of the resolution, reusability, and capability of multilayer surface micropatterning. Fabrication of a new plastic photomask for the exposure process simplifies the shadow mask fabrication process and results in higher resolution in the shadow mask structures compared to the commercial chromium photomasks. For the multilayer surface micropatterning technology, a simple and fast alignment technique based on SU‐8 pillars and without usage of any microscopic tools is reported. This unique method leads to a less complicated alignment process with the alignment accuracy of ≈2 µm. The proposed shadow mask technology can be easily employed for wafer‐scale micropatterning process. The capability of fabricated SU‐8 shadow masks in micropatterning on polymer thin films is evaluated by fabricating metallic contacts on poly(3,4‐ethylenedioxythiophene) samples and electrical characterization.
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