Patent ID: 7145177
Filing Date: 2006-12-05
Classification: H01L

Abstract:
1. A light emitting device comprising: a switching TFT provided over a substrate; an erase TFT provided over the substrate; a current control TFT provided over the substrate; an EL element provided over the substrate; and an n-channel driver TFT provided in a driver circuit and over the substrate, wherein impurity regions of the switching TFT and the erase TFT are electrically connected with a gate electrode of the current control TFT, wherein an impurity region of the current control TFT is electrically connected with the EL element, wherein gate electrodes of the switching TFT and the erase TFT exist at respective positions where the gate electrodes do not overlap the impurity regions of the switching TFT and the erase TFT, respectively, through a gate insulating film, wherein a gate electrode of the n-channel driver TFT overlaps a low concentration impurity region of the n-channel driver TFT, wherein the gate electrode of the switching TFT comprises a first conductive layer and a second conductive layer provided over the first conductive layer, wherein a side edge of the second conductive layer is aligned with a side edge of the first conductive layer, wherein the gate electrode of the erase TFT comprises a third conductive layer and a fourth conductive layer provided over the third conductive layer, and wherein a side edge of the fourth conductive layer is aligned with a side edge of the third conductive layer.