| 摘要 |
PURPOSE:To improve the film forming speed of the title device as well as to prevent the deterioration in film quality when a film is formed by a method wherein the DC potential difference (DC cell bias voltage) between electrodes is removed. CONSTITUTION:The anode side is earthed in most of the ordinary capacity coupling paralleled flat plate type devices, and the self bias based on the difference of the diffusion coefficient of electrons and ions is generated by the asymmetrical property between electrodes. As most of said bias is added to cathode as negative bias, the voltage of the sum of high frequency component and negative DC component is applied to the cathode side. As a result, a space charge layer is formed on the cathode side by positive ions, they are accelerated and come into collision with the cathode. Consequently, as the characteristics of the amorphous silicon film formed on a substrate placed on the cathode side are deteriorated considerably when compared with the anode side, the substrate is ordinarily placed on the anode side where the film forming speed is slow. In the circuit diagram of the capacity coupling paralleled flat plate type glow discharging device, a switch 6 is turned ON, and DC self-bias compensation voltage is applied from outside. As a result, the film forming speed can be improved by 50% at the highest. |
