| abstract |
It is an object to control quality of a microcrystalline semiconductor film or a semiconductor film including crystal grains so that operation characteristics of a semiconductor element typified by a TFT can be improved. It is another object to improve characteristics of a semiconductor element typified by a TFT by controlling a deposition process of a microcrystalline semiconductor film or a semiconductor film including crystal grains. In addition, it is another object to increase on-state current of a thin film transistor and to reduce off-state current of the thin film transistor. In a semiconductor layer including a plurality of crystalline regions in an amorphous structure, generation positions and generation density of crystal nuclei from which the crystalline regions start to grow are controlled, whereby quality of the semiconductor layer is controlled. In addition, after generation of crystal nuclei from which the crystalline regions start to grow in the semiconductor layer, an impurity element serving as a donor is added to the semiconductor layer, whereby crystallinity of the semiconductor layer is increased and the resistivity of the semiconductor layer is reduced. |