Patent ID: 8373171

Claim:
A light emitting device comprising: a substrate; a first transistor and a second transistor formed over the substrate; a current supply line is electrically connected with a drain wire of the second transistor; and a pixel electrode of an EL element is electrically connected with the second transistor, wherein a gate electrode of the second transistor comprises a first conductive layer, a second conductive layer, and a third conductive layer, wherein a drain wire of the first transistor is electrically connected with the gate electrode of the second transistor via a wire therebetween, wherein the first conductive layer extends beyond edges of the second conductive layer, wherein the second conductive layer is formed directly on a first upper surface of the first conductive layer, wherein the third conductive layer is formed over a second upper surface of the first conductive layer and the second conductive layer, wherein the third conductive layer is directly in contact with the second upper surface of the first conductive layer and directly in contact with upper and side surfaces of the second conductive layer, wherein the first conductive layer and the third conductive layer comprise a material selected from the group consisting of silicon, titanium, tantalum, tungsten and molybdenum, wherein the entire first conductive layer and the entire third conductive layer comprise different materials, wherein the first conductive layer and the second conductive layer comprise different materials, and wherein the second conductive layer and the third conductive layer comprise different materials.