Low temperature integration of high performance TFTs is critical to realize low cost displays and sensors. The successful development of high performance flexible devices will be dictated by the enhancement in the thermal stability of the flexible substrates and the low temperature processing of the high quality gate dielectric. The low temperature processing of dielectric thin films necessitates the development of processes and techniques with plasma controlled reaction kinetics dominating the thin film growth rather then the thermal state of the substrate. At the same time, the gate dielectric reliability needs to be maintained or enhanced. In the present work, we report on the low temperature processing of high quality gate dielectric films by high-density PECVD technique. The bulk and interfacial electrical quality and reliability of the MOS capacitors as a function of process temperature are discussed in this report. A comparison with the high temperature gate oxide films has been made to establish the film quality and reliability. The present films showed high electrical performance and reliability as evaluated in terms of the electrical, Si/SiO2 interfacial, and bias-temperature stress (BTS) reliability characteristics. The observed results are promising and suggest the suitability of HDP technique for novel device development on low temperature flexible substrates.