Circuit substrate, manufacturing method thereof and display device

Abstract

The present invention provides a circuit substrate that can reduce Cgd capacitance, sufficiently prevent the influence of Cgd capacitance on applied voltage, together with sufficiently make the reliability of the circuit substrate favorable, to provide a method of manufacturing thereof, and a display device. The circuit substrate of the present invention is a circuit substrate with a semiconductor element arranged on a transparent substrate, in which the semiconductor element is provided with an oxide semiconductor layer; the circuit substrate is provided with an etch-stop layer and a conductive layer, having a region overlapping with neither the etch-stop layer nor the conductive layer, and with at least one portion of the region overlapping with a cutout portion of the oxide semiconductor layer, when the main surface of the circuit substrate is planarly viewed; and a portion of an edge of a cutout portion of the oxide semiconductor layer is located on a side of the etch-stop layer beyond an edge of the etch-stop layer, when the main surface of the circuit substrate is planarly viewed.

1 . A circuit substrate comprising:
 a transparent substrate;   a semiconductor element disposed on the transparent substrate, said semiconductor element including a patterned oxide semiconductor layer;   an etch-stop layer covering at least a center portion of the oxide semiconductor layer, the etch-stop layer being made of an insulating material and having an opening therein; and   a patterned conductive layer covering at least a portion of the etch-stop layer, the patterned conductive layer including a source electrode, a source wiring line, and a drain electrode,   wherein a part of an edge of the oxide semiconductor layer is defined by an edge of the opening in the etch-stop layer and is tucked under said edge of the etch-stop layer.   
     
     
         2 . The circuit substrate according to  claim 1 , wherein another part of an edge of the oxide semiconductor layer is defined by an edge of the patterned conductive layer and is tucked under said edge of the patterned conductive layer. 
     
     
         3 . The circuit substrate according to  claim 1 , wherein the oxide semiconductor layer comprises indium, gallium, zinc, and oxide. 
     
     
         4 . The circuit substrate according to  claim 1 ,
 wherein the patterned conductive layer is a laminate of at least two layers, including a layer having at least one selected from a group comprising aluminum and copper and a layer having at least one selected from a group comprising titanium, molybdenum, and chromium, and   wherein the layer having at least one selected from a group comprising titanium, molybdenum, and chromium is disposed on a surface side of the conductive layer.   
     
     
         5 . The circuit substrate according to  claim 1 , wherein the semiconductor element is a thin film transistor. 
     
     
         6 . A method of manufacturing a circuit substrate comprising a semiconductor element disposed on a transparent substrate, said method comprising:
 forming an island-shaped oxide semiconductor layer on the transparent substrate;   forming a patterned etch-stop layer made of an insulating material so as to cover at least a center portion of the island-shaped oxide semiconductor layer;   depositing a conductive layer over an entire surface of the transparent substrate including a region over the patterned etch-stop layer;   forming a patterned resist on the conductive layer; and   etching the conductive layer using the patterned resist as a mask to form a patterned conductive layer from the conductive layer, wherein the patterned conductive layer includes a source electrode, a source wiring line, and a drain electrode, and continuing to etch the island-shaped oxide semiconductor thereunder using the patterned conductive layer and the patterned etch-stop layer as a mask to form a cutout in the island-shaped oxide semiconductor layer.   
     
     
         7 . The method of manufacturing a circuit substrate according to  claim 6 , wherein wet-etching with the same etchant is used in etching the conductive layer and in etching the island-shaped oxide semiconductor layer underneath. 
     
     
         8 . The method of manufacturing a circuit substrate according to  claim 6 , further comprising, after forming the patterned conductive layer and forming the cutout in the island-shaped oxide semiconductor layer, forming an insulating layer. 
     
     
         9 . A circuit substrate made by the method of manufacturing a circuit substrate according to  claim 6 , the circuit substrate comprising:
 the transparent substrate;   the semiconductor element disposed on the transparent substrate, said semiconductor element including the patterned oxide semiconductor layer;   the etch-stop layer covering at least the center portion of the oxide semiconductor layer, the etch-stop layer having an opening therein; and   the patterned conductive layer covering at least a portion of the etch-stop layer, the patterned conductive layer including the source electrode, the source wiring line, and the drain electrode,   wherein an edge of the cutout of the oxide semiconductor layer is defined by an edge of the opening in the etch-stop layer and is tucked under said edge of the etch-stop layer.   
     
     
         10 . A display device, comprising:
 the circuit substrate according to  claim 1 ; and   an opposite substrate coupled to the circuit substrate.   
     
     
         11 . The method of manufacturing a circuit substrate according to  claim 6 , wherein the island-shaped oxide semiconductor layer comprises indium, gallium, zinc, and oxide.