Patent ID: 8383434
Filing Date: 2013-02-26
Classification: H01L

Abstract:
1. A method for manufacturing a thin film transistor comprising steps of: forming a gate electrode over a substrate; forming a gate insulating film over the substrate and the gate electrode; forming a first microcrystalline semiconductor film over the gate insulating film under a first condition; forming a second microcrystalline semiconductor film over the first microcrystalline semiconductor film under a second condition; forming a semiconductor film including a microcrystalline semiconductor region and an amorphous semiconductor region over the second microcrystalline semiconductor film; forming a first impurity semiconductor film over the semiconductor film; etching a part of the first impurity semiconductor film to form an island-shaped second impurity semiconductor film; etching parts of the first microcrystalline semiconductor film, the second microcrystalline semiconductor film, and the semiconductor film to form an island-shaped first semiconductor stack; forming a pair of wirings over the island-shaped second impurity semiconductor film; etching the island-shaped second impurity semiconductor film to form a pair of impurity semiconductor films; etching a part of the island-shaped first semiconductor stack to form a second semiconductor stack in which a microcrystalline semiconductor region and a pair of amorphous semiconductor regions are stacked; forming an insulating film over the pair of wirings after forming the second semiconductor stack, wherein the pair of amorphous semiconductor regions is spaced from each other, wherein the insulating film is in contact with the microcrystalline semiconductor region in a region between the pair of amorphous semiconductor regions, wherein the first condition is a condition in which a microcrystalline semiconductor film in which a space between crystal grains is filled with an amorphous semiconductor is formed, and wherein the second condition is a condition in which crystal growth proceeds.