摘要 |
A metal element typified by Ni has an adverse effect on device properties of a TFT, and consequently, a step for removing the elements (hereinafter referred to as a gettering step) has been carried out. However, gettering steps as described above have the disadvantage of high cost due to an increase in the number of steps. Accordingly, a manufacturing method of a crystalline semiconductor film, which does not require a gettering step, has been in demand. A TFT of the present invention is characterized by reducing the concentration of the metal element, typically Ni, in the crystalline semiconductor film to less than 4x10<16 >atoms/cm<3>, more specifically, 5x10<15 >atoms/cm<3 >to 3x10<16 >atoms/cm<3>, preferably, 7x10<15 >atoms/cm<3 >to 3x10<16 >atoms/cm<3>. And the present invention enables crystallization even by the metal element with a low concentration and an omission of a gettering step.
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