Synthesis of High Quality SiO$_{2}$ Film by Capacitively-Coupled Plasma CVD with Comb-Type Electrodes

Recently, flexible displays with lightness and flexibility attract much attention as next generation displays. To achieve the flexible display, thin film transistors (TFTs) on a plastic substrate at low temperature should be fabricated. The low-temperature deposition of a gate insulator is one of the key technology for the low-temperature fabrication of TFTs. In this study, we design a capacitively-coupled plasma with comb-shaped electrodes for low-temperature deposition of SiO$_{2}$ films. The influences of the deposition parameters, such as the pressure and the distance between the substrate and the electrode, on the film properties of SiO$_{2 }$were investigated. The deposition rate increased with increasing the deposition pressure and decreasing the distance between the dielectric and the substrate ($D_{d-s})$. On the other hand, the BHF etching rate decreased as the deposition pressure and the $D_{d-s}$ decreased, indicating that the densification of the films was enhanced. The deposited SiO$_{2}$ exhibit good insulating properties, which were the cuurent density of 1.9 nA/cm$^{2}$ and the breakdown voltage of 7.4 MV/cm. These results indicate that the SiO$_{2}$ films deposited by a capacitively-coupled plasma CVD with comb-shaped electrodes can apply to the gate insulator of TFTs.