Molds and Resists Studies for Nanoimprint Lithography of Electrodes in Low-Voltage Polymer Thin-Film Transistors

Author(s)

Cavallari, Marco Roberto ^[1] ; Zanchin, Vinicius Ramos ^[1] ; Pojar, Mariana ^[1] ; Seabra, Antonio Carlos ^[1] ; Pereira-da-Silva, Marcelo De Assumpcao ^{[2, 3]} ; Fonseca, Fernando Josepetti ^[1] ; De Andrade, Adnei Melges ^[4]

Affiliation

^[1] Univ Sao Paulo EPUSP, Dept Engn Sistemas Eletron, Escola Politecn, BR-05508900 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil

^[3] UNICEP, Ctr Univ Cent Paulista, BR-13563470 Sao Carlos, SP - Brazil

^[4] Univ Sao Paulo, IEE, BR-05508970 Sao Paulo - Brazil

• Document type: Journal article
• Source: JOURNAL OF ELECTRONIC MATERIALS; v. 43, n. 5, p. 1317-1325, MAY 2014.
• Web of Science Citations: 5

Abstract

A low-cost patterning of electrodes was investigated looking forward to replacing conventional photolithography for the processing of low-operating voltage polymeric thin-film transistors. Hard silicon, etched by sulfur hexafluoride and oxygen gas mixture, and flexible polydimethylsiloxane imprinting molds were studied through atomic force microscopy (AFM) and field emission gun scanning electron microscopy. The higher the concentration of oxygen in reactive ion etching, the lower the etch rate, sidewall angle, and surface roughness. A concentration around 30 % at 100 mTorr, 65 W and 70 sccm was demonstrated as adequate for submicrometric channels, presenting a reduced etch rate of 176 nm/min. Imprinting with positive photoresist AZ1518 was compared to negative SU-8 2002 by optical microscopy and AFM. Conformal results were obtained only with the last resist by hot embossing at 120 A degrees C and 1 kgf/cm(2) for 2 min, followed by a 10 min post-baking at 100 A degrees C. The patterning procedure was applied to define gold source and drain electrodes on oxide-covered substrates to produce bottom-gate bottom-contact transistors. Poly(3-hexylthiophene) (P3HT) devices were processed on high-kappa titanium oxynitride (TiO (x) N (y) ) deposited by radiofrequency magnetron sputtering over indium tin oxide-covered glass to achieve low-voltage operation. Hole mobility on micrometric imprinted channels may approach amorphous silicon (similar to 0.01 cm(2)/V s) and, since these devices operated at less than 5 V, they are not only suitable for electronic applications but also as sensors in aqueous media. (AU)

• FAPESP's process: 09/05589-7 - Study and develoment of organic LEDs, solar cells, thin-film transistors and sensors based on semiconductor polymers
• Grantee: Adnei Melges de Andrade
• Support Opportunities: Regular Research Grants