Patent ID: 8624321
Filing Date: 2014-01-07
Classification: H01L

Abstract:
1. A thin film transistor comprising: a gate insulating layer covering a gate electrode; a first microcrystalline semiconductor layer and a second microcrystalline semiconductor layer provided over the gate insulating layer, both the first microcrystalline semiconductor layer and the second microcrystalline semiconductor layer including an impurity element serving as a donor; a third microcrystalline semiconductor layer provided over the first microcrystalline semiconductor layer, the second microcrystalline semiconductor layer and the gate insulating layer, the third microcrystalline semiconductor layer being in contact with the gate insulating layer between the first microcrystalline semiconductor layer and the second microcrystalline semiconductor layer; an amorphous semiconductor layer provided over the third microcrystalline semiconductor layer; and a first semiconductor layer and a second semiconductor layer provided over and in contact with the amorphous semiconductor layer, both the first semiconductor layer and the second semiconductor layer including an impurity element imparting one conductivity type, both the first semiconductor layer and the second semiconductor layer not being in contact with the third microcrystalline semiconductor layer, wherein the gate insulating layer has a first thickness in a first portion between the first microcrystalline semiconductor layer and the second microcrystalline semiconductor layer, and a second thickness in a second portion in contact with the first microcrystalline semiconductor layer or the second microcrystalline semiconductor layer, wherein the first portion is in contact with the second portion, wherein the first portion does not overlap with the first microcrystalline semiconductor layer and the second microcrystalline semiconductor layer, and wherein the first thickness is smaller than the second thickness.