| 摘要 |
PROBLEM TO BE SOLVED: To provide a gate insulating film suitable to an insulated-gate type transistor, which is represented by a TFT, and the forming method of the gate insulating film and to make it possible to ensure the stability and reliability of the characteristics, such as a Vth and a value S, of the TFT using such the gate insulating film. SOLUTION: An oxynitride silicon film is formed using an SiH4, an N2O and H2 by a plasma CVD method and this film is applied to a gate insulating film of a TFT. The characteristics of the silicon film are controlled by chiefly changing the flow rates of the N2O and the H2. The hydrogen concentration and the nitrogen concentration in the silicon film can be increased within the above range of the Vth and the value S by increasing the flow rate of the H2. Moreover, by increasing the flow rate of the N2O, the hydrogen concentration and the nitrogen concentration in the oxynitride silicon film are decreased and the oxygen concentration in the silicon film can be increased. |
