Liquid-phase deposited (LPD) oxide has previously been successfully applied to low temperature processed polysilicon thin film transistors (poly-Si TFTs) as a gate insulator. This paper shows the feasibility of applying room temperature deposited LPD oxide to high temperature processed devices. The thermal effects of high temperature processing on poly-Si TFTs including postoxide annealing and dopant activation have been investigated. These high temperature treatments show excellent improvement in device characteristics. In addition, the novel devices also show considerably more efficient hydrogenation during NH3-plasma treatment, and their reliability under de electrical stress appears similar to that of conventional poly-Si TFTs.