Performance of four-terminal low-temperature polycrystalline-silicon thin-film transistors and their application in CMOS inverters on glass substrates

Abstract

High-performance and low-power-operation CMOS circuits comprising low-temperature (LT) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) are indispensable for integrated circuits on glass substrate. The fabrication of high-quality poly-Si films with large grains can enhance the on-current of TFTs on glass substrates owing to low carrier scattering. In this study, we used continuous-wave laser lateral crystallization (CLC) to fabricate high-quality thin poly-Si films on a glass substrate. To achieve low-power operation, precise threshold voltage (Vth) control is most important, and four-terminal (4T) TFT is one attractive approach to achieve it. We fabricated a CMOS inverter comprising 4T CLC LT poly-Si TFTs on a glass substrate and confirmed nearly identical controllability of Vth, subthreshold swing, and mobility of n- and p-channel TFTs in CMOS inverter as compared with TFTs fabricated on different glass substrates with their own processes. By using the high controllability of 4T CLC LT poly-Si TFTs, we successfully operated the CMOS inverter with Vdd = 1.0 V.