Fabricating Parylene-C Shadow Masks for Applications in Short- Channel Top-Contact Carbon Nanotube Flexible Transistors

Flexible transistors with semiconducting carbon nanotubes offer better mobility and stability than current organic material transistors for applications in flexible display and sensor devices. With carbon nanotubes as the semiconducting material, the transistors offer a higher performance due to the extraordinary electrical properties of singlewalled carbon nanotubes (SWNTs). However, conventional metal shadow masks can only create flexible device transistors with a channel length of 50 μm or greater. Parylene-C shadow masks can be used instead of metal masks because of their flexibility, adaptability for patterning, and their ability to fabricate transistors with much smaller channel lengths. Previously it has been shown that Parylene-C masks allow for a fine resolution with a smallest feature size of 4 μm. We fabricated masks with features as small as 2 μm wide, and additionally used our masks to create short-channel transistors. We successfully constructed short-channel top-contact SWNT network inflexible and flexible transistors on silicon (Si) and polyamide substrates with a mobility of 0.1 to 2 cm2/V-s and on/off ratios on the magnitude of 102 to 103.