Seo Jung-Hun, Ling Tao, Gong Shaoqin, Zhou Weidong, Ma Alice L, Guo L Jay, Ma Zhenqiang
Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Department of Electrical Engineering and Computer Science, University of Michigan-Ann Arbor, Ann Arbor, MI 48109, USA.
Sci Rep. 2016 Apr 20;6:24771. doi: 10.1038/srep24771.
The simplification of fabrication processes that can define very fine patterns for large-area flexible radio-frequency (RF) applications is very desirable because it is generally very challenging to realize submicron scale patterns on flexible substrates. Conventional nanoscale patterning methods, such as e-beam lithography, cannot be easily applied to such applications. On the other hand, recent advances in nanoimprinting lithography (NIL) may enable the fabrication of large-area nanoelectronics, especially flexible RF electronics with finely defined patterns, thereby significantly broadening RF applications. Here we report a generic strategy for fabricating high-performance flexible Si nanomembrane (NM)-based RF thin-film transistors (TFTs), capable of over 100 GHz operation in theory, with NIL patterned deep-submicron-scale channel lengths. A unique 3-dimensional etched-trench-channel configuration was used to allow for TFT fabrication compatible with flexible substrates. Optimal device parameters were obtained through device simulation to understand the underlying device physics and to enhance device controllability. Experimentally, a record-breaking 38 GHz maximum oscillation frequency fmax value has been successfully demonstrated from TFTs with a 2 μm gate length built with flexible Si NM on plastic substrates.
对于大面积柔性射频（RF）应用而言，能够定义非常精细图案的制造工艺的简化是非常可取的，因为在柔性基板上实现亚微米级图案通常极具挑战性。传统的纳米级图案化方法，如电子束光刻，不易应用于此类应用。另一方面，纳米压印光刻（NIL）的最新进展可能使大面积纳米电子器件的制造成为可能，特别是具有精细定义图案的柔性射频电子器件，从而显著拓宽射频应用范围。在此，我们报告了一种通用策略，用于制造基于高性能柔性硅纳米膜（NM）的射频薄膜晶体管（TFT），理论上能够在超过100 GHz的频率下工作，其沟道长度采用NIL图案化的深亚微米尺度。采用独特的三维蚀刻沟槽沟道配置，以实现与柔性基板兼容的TFT制造。通过器件模拟获得了最佳器件参数，以了解潜在的器件物理特性并增强器件可控性。在实验中，在塑料基板上用柔性硅NM构建的栅长为2μm的TFT成功展示了创纪录的38 GHz最大振荡频率fmax值。
