THE MECHANISM AT WORK IN 40 MHZ DISCHARGE SIH4 NH3/N-2 PLASMA CHEMICAL-VAPOR-DEPOSITION OF SINX FILMS AT VERY RATES/

This paper reports a study on the mechanism involved in depositing SiN x films at very high rates buy using 40 MHz discharge SiH4/NH3/N-2 pla sma enhanced chemical vapor deposition (PECVD). The quality of the fil ms is comparable to that of films deposited at low rates at a conventi onal 13.56 Mhz frequency. From film deposition experiments, plasma dia gnostic studies, and analytical calculation for both frequencies, we h ave found that the mechanism of depositing SiNx films at very high rat es with a 40 Mhz discharge can be explained by the higher dissociation efficiency of both NH3 gas and SiH4 gas than at a conventional 13.56 Mhz. We also report the performance of a thin film transistor (TFT), a pplicable to LCD switching devices, that was fabricated with SiNx film deposited at the high rate of 350 nm/min with a 40 MHZ frequency.