| 摘要 |
PURPOSE: To obtain a method for manufacturing a semiconductor device in which the variation of a threshold voltage caused by breakthrough a dopant can be suppressed appropriately. CONSTITUTION: An amorphous silicon film 21 is heavily doped with hydrogen ions 40. Consequently, the amorphous silicon film 21 is formed in a hydrogen ion implantation layer 41. It is then heat-treated and columnar grains are formed in the amorphous silicon film 21 except a part where the hydrogen ion implantation layer 41 is formed. On the other hand, columnar grains are formed in the hydrogen ion implantation layer 41. A columnar grain layer 42 has a large number of grain boundaries extending in many directions, e.g. a grain boundary extending along the thickness direction of a polysilicon film 44a, a grain boundary extending along the direction other than the thickness direction of the polysilicon film 44a.
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