Properties of a-Si:H Film Deposited by Amplitude-Modulated RF Plasma Chemical Vapour Deposition for Thin Film Transistor

The method of amplitude-modulated RF plasma enhanced chemical vapour deposition (p-CVD) has been used to deposit the a-Si:H film. Various properties of the deposited a-Si:H film such as uniformity of thickness, stress of film and hydrogen concentration in the film are studied. These film properties are improved in the case of amplitude-modulated RF p-CVD compared with the CW case, particularly at the high deposition rate. Further investigation has been carried out by constructing a bottom gate thin film transistor (TFT) device without an etch stop layer. The measured electron mobility and threshold voltage, are also improved up to the deposition rate of 32 nm/min by the method of amplitude modulated RF p-CVD at the modulation frequency of 68 kHz.