Low-Temperature Stacked Gate Insulator by Photo Oxidation and PECVD for High-Performance TFT LCDs
Yukihiko NakataTakashi ItogaTetsuya Okamoto
Toshimasa HamadaYutaka Ishii
A novel gate insulator formation method for Poly-Si TFTs was developed to reduce
the process temperature and to improve the device performance. Excellent SiO2/Si
interfaces with an interface state density of 2-3x1010/cm2/eV was obtained by photo oxidation under irradiation of Xe excimer light at 200-300C. This interface state density is the same as that of thermal oxidation at 950C and is about 1/4 of the current standard gate insulator for Poly-Si TFTs. Also, a stacked film of a 3 nm photo oxide and a 40 nm PECVD film using TEOS gas without annealing has the same electric characteristics of the current standard gate insulator, in spite of the low process temperature and the film thickness being less than half of the standard one. The stacked gate insulator composed by photo oxide and PECVD film is promising in reducing process temperature and improving performance.