| abstract |
An object of the present invention is to propose a thin film transistor with high electrical characteristics and high reliability even when a large-area substrate is used, and a display device using the thin film transistor. A step of forming a gate electrode over a substrate, a step of forming a gate insulating film over the gate electrode, a step of forming a microcrystalline semiconductor film over the gate insulating film using a plasma CVD method, A step of forming an amorphous semiconductor film over the crystalline semiconductor film, and in the step of forming the microcrystalline semiconductor film, after the pressure in the reaction chamber is temporarily set to 10 −5 Pa or lower, the temperature of the substrate is set to 120 ° C. or higher. A microcrystalline semiconductor film is formed by introducing hydrogen and silicon gas at a temperature of 220 ° C. or lower to generate plasma, and forming a film while removing the reaction product formed on the gate insulating film surface by applying hydrogen plasma. Form. In addition, the plasma is generated by superimposing the first high-frequency power for applying the high-frequency power in the HF band and the second high-frequency power in the VHF band. [Selection] Figure 1 |