Direct optical polymer structuring
As a platform for electronic devices, polymer materials offer the advantages of intrinsic flexibility and stretchability compared to devices made of hard material. In contrast to materials such as silicon, however, there are only a few tools for structuring large-area monolithic components. Zheng et al. developed an optical lithography technique for the high-throughput production of transistor circuits on stretchable substrates. This process uses ultraviolet light to control the local solubility of the polymer, which enables the fabrication of transistors in the micrometer range. These devices can be manufactured in high yield and excellent uniformity without affecting their electronic and mechanical properties.
science, abh3551, this edition p. 88
Polymer electronic materials have made soft and stretchable electronics possible. However, the lack of a universal micro / nano fabrication process for skin-like and elastic circuits results in low device density and limited parallel signal recording and processing compared to silicon-based devices. We present a monolithic optical microlithography process that directly microstructures a range of elastic electronic materials through sequential ultraviolet light induced solubility modulation. We made transistors with channel lengths of 2 micrometers at a density of 42,000 transistors per square centimeter. We made elastic circuits with an XOR gate and a half adder, both of which are essential components of an arithmetic logic unit. Our process provides a way to fabricate complex, high-density, multi-layer elastic circuits at the wafer level with performance that rivals that of their rigid counterparts.