Low-temperature poly-Si TFTs with sputtered HfO2 gate stack on glass substrate

Abstract

We discussed the performance of continuous-wave laser lateral crystallization (CLC) low-temperature (LT) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) fabricated at 550 °C with a sputtered metal gate and sputtered HfO₂ gate dielectric on a nonalkaline glass substrate. The obtained field-effect mobility of CLC LT poly-Si TFTs with a HfO₂ gate stack was 180 cm²/V s. However, the mobility of the HfO₂ gate stack is lower than that of the PECVD-SiO₂ gate stack. It was concluded that this is caused by scattering at defects and imperfections of both the inter layer (IL) SiO₂ and the IL-SiO₂/Si interface, but not by remote scattering from the high-k dielectric.