Print-patterned polymer-semiconductor and amorphous silicon active-matrix display
Manufacturing inexpensive, flexible electronics such as displays and radio tags will depend upon eschewing rigid substrates and adopting roll-to-roll (R2R) processing. One of the challenges of R2R transistor arrays is misregistration caused by substrate warpage. Digital lithography is a process for both additive and subtractive patterning of materials using jet-printing and camera-controlled active registration. Active registration can eliminate defects caused by substrate warpage. In additive digital lithography, material is directly jetted where needed onto a substrate. This reduces the usual deposit material/apply resist/pattern/develop/etch/strip sequence of conventional microelectronic processing to a single step. Subtractive digital lithography is more conventional: it replaces the apply resist/pattern/develop steps with a single printing step, followed by etching and stripping. The simplicity of additive digital lithography makes it attractive for flexible microelectronic manufacturing. But some classes of materials do not have sufficient performance when applied as a liquid, and microstructural differences between jetted and blanket-deposited material present a challenge, particularly for plastic semiconductors which depend on molecular order (pi-pi stacking) for good performance. We have developed print-patterned active matrices based on n-type amorphous Silicon and p-type poly(thiophene). Xerox poly(thiophene) is a high performance (mob=0.1 cm2/V.s) oxygen-stable semiconducting polymer that can be additively printed. In this work, we will show transistor array performance curves as well as measurements from displays driven by an active matrix of print-patterned transistors.
Apte, R. B. ; Street, R. A. ; Paul, K. ; Salleo, A. ; Chabinyc, M. ; Ready, S. E. ; Arias, A. C. Print-patterned polymer-semiconductor and amorphous silicon active-matrix display. USDC Third Annual Flexible Displays and Microelectronics Conference; 2004 February 10-12; Phoenix; AZ; USA.