Fabricating thin-film transistors on plastic substrates using spin etching and device transfer

Abstract

This work presents a novel method for transferring thin-film transistors (TFTs) from a Si wafer to another flexible plastic substrate. First, high-performance poly-Si TFTs were fabricated on a 1.5 mu m thick SiO2 on a Si wafer and then attached to a flexible plastic substrate by optical adhesive. Next, spin-etching was utilized to remove the backside Si, using SiO2 as a stopping layer. A qualitative model was established to explain the relationship between the chemical flow rate/rotation speed to the etching rate and the uniformity of Si removal. The Si etching rate exceeded 200 mu m/min while the Si to SiO2 selectivity of 250 was maintained given optimized spin-etching parameters. Substrate bonding and Si spin-etching steps caused no degradation or yield loss as compared to the electrical characteristics before transference. Additionally, extrinsic stress only weakly affected the properties of poly-Si resistors and TF`Ts on a flexible plastic substrate. (c) 2005 The Electrochemical Society. [DOI: 10. 1149/1.1860491] All rights reserved.