Effect of Ar⁺ ion bombardment during hydrogenated amorphous silicon film growth in plasma chemical vapor deposition system

We have developed the double tubed coaxial line type microwave plasma chemical vapor deposition (MPCVD) system to fabricate hydrogenated amorphous silicon (a-Si:H) films. We have studied the influence of Ar⁺ ion bombardment during a-Si:H film growth and clarified that the ion bombardment causes film surface heating effect and ion implanting effect. It is not sufficient to discuss only whether films are of good quality or not, when the ion bombardment energy is increased. In this study, we show that the effect of ion bombardment can be separated into the film surface heating effect and the ion implanting effect and discuss the influence of each effect on the film properties. We also show that the film surface temperature can be expressed as a function of the sheath voltage. It is clarified that a film with low dangling bond density can be fabricated at low temperatures if there is no ion bombardment.