Semiconductor device

Abstract

A semiconductor device includes a semiconductor layer over a substrate; a gate insulating film covering the semiconductor layer; a gate wiring including a gate electrode, which is provided over the gate insulating film and is formed by stacking a first conductive layer and a second conductive layer; an insulating film covering the semiconductor layer and the gate wiring including the gate electrode; and a source wiring including a source electrode, which is provided over the insulating film, is electrically connected to the semiconductor layer, and is formed by stacking a third conductive layer and a fourth conductive layer. The gate electrode is formed using the first conductive layer. The gate wiring is formed using the first conductive layer and the second conductive layer. The source electrode is formed using the third conductive layer. The source wiring is formed using the third conductive layer and the fourth conductive layer.

1 . A semiconductor device comprising:
 a semiconductor layer provided over a substrate;   a first wiring which is electrically connected to the semiconductor layer and includes a first electrode;   an insulating film covering the semiconductor layer and the first electrode; and   a second wiring which is provided over the semiconductor layer with the insulating film interposed therebetween and includes a second electrode,   wherein the first electrode includes a first conductive layer,   wherein the first wiring includes the first conductive layer and a second conductive layer,   wherein the second electrode includes a third conductive layer,   wherein the second wiring includes the third conductive layer and a fourth conductive layer, and   wherein each of the first conductive layer and the third conductive layer has a light-transmitting property.   
   
   
       2 . The semiconductor device according to  claim 1 , wherein electric conductivity of each of the second conductive layer and the fourth conductive layer is higher than electric conductivity of each of the first conductive layer and the third conductive layer. 
   
   
       3 . The semiconductor device according to  claim 1 , wherein each of the second conductive layer and the fourth conductive layer has a light-blocking property. 
   
   
       4 . The semiconductor device according to  claim 1 , wherein the second conductive layer is formed using a material which is different from a material of the fourth conductive layer. 
   
   
       5 . The semiconductor device according to  claim 1 , wherein the second conductive layer is formed using a metal material, a metal compound, or an alloy containing one or more elements selected from aluminum, tungsten, titanium, tantalum, molybdenum, nickel, platinum, copper, gold, silver, manganese, neodymium, chromium, antimony, niobium, or cerium; or a nitride of the metal material. 
   
   
       6 . The semiconductor device according to  claim 1 , wherein the fourth conductive layer is formed using a metal material, a metal compound, or an alloy containing one or more elements selected from aluminum, tungsten, titanium, tantalum, molybdenum, nickel, platinum, copper, gold, silver, manganese, neodymium, chromium, antimony, niobium, or cerium; or a nitride of the metal material. 
   
   
       7 . The semiconductor device according to  claim 1 , wherein the semiconductor layer contains at least one of indium, gallium, and zinc. 
   
   
       8 . The semiconductor device according to  claim 1 , wherein the substrate has an insulating surface. 
   
   
       9 . The semiconductor device according to  claim 1 , wherein the first electrode is a source electrode. 
   
   
       10 . The semiconductor device according to  claim 1 , wherein the first electrode is not covered with the second conductive layer. 
   
   
       11 . A semiconductor device comprising:
 a semiconductor layer provided over a substrate;   a first wiring which is connected to the semiconductor layer and includes a first electrode;   an insulating film covering the semiconductor layer and the first electrode;   a second wiring which is provided over the semiconductor layer with the insulating film interposed therebetween and includes a second electrode; and   a third wiring,   wherein the first electrode includes a first conductive layer,   wherein the first wiring includes the first conductive layer and a second conductive layer,   wherein the second electrode includes a third conductive layer,   wherein the second wiring includes the third conductive layer and a fourth conductive layer,   wherein the third wiring includes a fifth conductive layer and a sixth conductive layer, and   wherein each of the first conductive layer and the third conductive layer has a light-transmitting property.   
   
   
       12 . The semiconductor device according to  claim 11 , wherein electric conductivity of each of the second conductive layer and the fourth conductive layer is higher than electric conductivity of each of the first conductive layer and the third conductive layer. 
   
   
       13 . The semiconductor device according to  claim 11 , wherein each of the second conductive layer and the fourth conductive layer has a light-blocking property. 
   
   
       14 . The semiconductor device according to  claim 11 , wherein the second conductive layer is formed using a material which is different from a material of the fourth conductive layer. 
   
   
       15 . The semiconductor device according to  claim 11 , wherein the second conductive layer is formed using a metal material, a metal compound, or an alloy containing one or more elements selected from aluminum, tungsten, titanium, tantalum, molybdenum, nickel, platinum, copper, gold, silver, manganese, neodymium, chromium, antimony, niobium, or cerium; or a nitride of the metal material. 
   
   
       16 . The semiconductor device according to  claim 11 , wherein the fourth conductive layer is formed using a metal material, a metal compound, or an alloy containing one or more elements selected from aluminum, tungsten, titanium, tantalum, molybdenum, nickel, platinum, copper, gold, silver, manganese, neodymium, chromium, antimony, niobium, or cerium; or a nitride of the metal material. 
   
   
       17 . The semiconductor device according to  claim 11 , wherein the semiconductor layer contains at least one of indium, gallium, and zinc. 
   
   
       18 . The semiconductor device according to  claim 11 , wherein the substrate has an insulating surface. 
   
   
       19 . The semiconductor device according to  claim 11 , wherein the first electrode is a source electrode. 
   
   
       20 . The semiconductor device according to  claim 11 , wherein the first electrode is not covered with the second conductive layer. 
   
   
       21 . A method for manufacturing a semiconductor device, comprising the steps of:
 forming a semiconductor layer over a substrate;   forming a first conductive film and a second conductive film over the semiconductor layer;   forming a first conductive layer and a second conductive layer by etching the first conductive film and the second conductive film in a first etching step with the use of a first mask formed over the second conductive film;   forming a second mask by ashing of the first mask;   exposing part of the first conductive layer by etching the second conductive layer in a second etching step with the use of the second mask;   forming an insulating film so as to cover the first conductive layer, the second conductive layer, and the semiconductor layer;   forming a third conductive film and a fourth conductive film over the insulating film;   forming a third conductive layer and a fourth conductive layer by etching the third conductive film and the fourth conductive film in a third etching step with the use of a third mask formed over the fourth conductive film;   forming a fourth mask by ashing of the third mask; and   exposing part of the third conductive layer by etching the fourth conductive layer in a fourth etching step with the use of the fourth mask,   wherein each of the first conductive layer and the third conductive layer is formed using a light-transmitting material.   
   
   
       22 . The method for manufacturing a semiconductor device, according to  claim 21 , wherein each of the second conductive layer and the fourth conductive layer is formed using a material having higher electric conductivity than a material of each of the first conductive layer and the third conductive layer. 
   
   
       23 . The method for manufacturing a semiconductor device, according to  claim 21 , wherein each of the second conductive layer and the fourth conductive layer has a light-blocking property. 
   
   
       24 . The semiconductor device according to  claim 21 , wherein the substrate has an insulating surface. 
   
   
       25 . The semiconductor device according to  claim 21 , wherein the first conductive layer includes a source electrode.