Circuit board and display device

Abstract

A source and drain electrode layer ( 3 s /3 d ) of an oxide TFT element ( 3 ) is formed by a first conductive layer. A gate electrode ( 3 g ) of the oxide TFT element ( 3 ) and a gate electrode ( 5 g ) of an a-Si TFT element ( 5 ) are formed by a single conductive layer, that is, a second conductive layer. A source and drain electrode layer ( 5 s /5 d ) of the a-Si TFT element ( 5 ) is formed by a third conductive layer. The third conductive layer is formed above the second conductive layer in a thickness direction in which each conductive layer is stacked on an insulating substrate ( 2 ). Further, the first conductive layer is formed below the second conductive layer in the thickness direction. Therefore, it is possible to provide a circuit board that can have an improved degree of integration of transistor elements formed on the insulating substrate.

1 . A circuit board comprising:
 a first transistor element including a first semiconductor layer serving as a channel layer;   a second transistor element including a second semiconductor layer serving as a channel layer; and   a first conductive layer, a second conductive layer and a third conductive layer as electrode formative layers by which the first transistor element and the second transistor element are formed,   the first transistor element and the second transistor element being provided on one surface of a single insulating substrate,   the first conductive layer forming a gate electrode of the first transistor element,   the third conductive layer forming a gate electrode of the second transistor element,   the second conductive layer forming both of (a) a pair of source and drain electrodes of the first transistor element and (b) a pair of source and drain electrodes of the second transistor element,   one of the first conductive layer and the third conductive layer being formed above the second conductive layer in a thickness direction in which the first conductive layer, the second conductive layer, and the third conductive layer are stacked on the insulating substrate,   the other one of the first conductive layer and the third conductive layer being formed below the second conductive layer in the thickness direction in which the first conductive layer, the second conductive layer, and the third conductive layer are stacked on the insulating substrate.   
     
     
         2 - 5 . (canceled) 
     
     
         6 . The circuit board as set forth in  claim 1 , wherein the first transistor element and the second transistor element are formed so as to partially overlap each other when viewed from above. 
     
     
         7 . The circuit board as set forth in  claim 1 , wherein the first semiconductor layer and the second semiconductor layer are made of different materials, respectively. 
     
     
         8 . The circuit board as set forth in  claim 1 , wherein:
 the second semiconductor layer is a semiconductor layer which contains an amorphous silicon layer and/or a microcrystalline silicon layer;   the first transistor element and the second transistor element constitute a light sensor circuit;   the first transistor element serves as a sensor output of the light sensor circuit; and   the second transistor element serves as a light sensor element of the light sensor circuit.   
     
     
         9 . The circuit board as set forth in  claim 1 , wherein the first semiconductor layer is an oxide semiconductor layer. 
     
     
         10 . The circuit board as set forth in  claim 1 , further comprising a capacitor element including:
 (a) a capacitor electrode formed by the second conductive layer; and   (b) a capacitor counter electrode formed by either the first conductive layer or the third conductive layer, the capacitor counter electrode being formed so that at least a part of the capacitor counter electrode overlaps with the capacitor electrode when viewed from above.   
     
     
         11 . The circuit board as set forth in  claim 1 , wherein:
 the insulating substrate is provided with a display region;   the display region is provided with a plurality of pixels arranged in a matrix manner;   one of the first transistor element and the second transistor element is provided as a switching element for controlling each of the plurality of pixels to be turned on/off;   the other one of the first transistor element and the second transistor element is provided in at least a part of the plurality of pixels; and   the first transistor element and the second transistor element are formed so as to at least partially overlap each other when viewed from above.   
     
     
         12 . The circuit board as set forth in  claim 11 , wherein:
 in each of the plurality of pixels, the first transistor element is formed as the switching element for controlling each of the plurality of pixels to be turned on/off, the first transistor element including the first semiconductor layer made of an oxide semiconductor layer; and   in at least a part of the plurality of pixels, the second transistor element is formed, the second transistor element including the second semiconductor layer made of a semiconductor layer containing an amorphous silicon layer and/or a microcrystalline silicon layer, the second transistor element constituting a light sensor circuit.   
     
     
         13 . The circuit board as set forth in  claim 11 , further comprising:
 a drive circuit for driving each of the first transistor element and the second transistor element formed in the display region, the drive circuit being provided in a peripheral region of the display region,   the drive circuit including the first transistor element including the first semiconductor layer made of an oxide semiconductor layer.   
     
     
         14 . The circuit board as set forth in  claim 11 , further comprising:
 a protective circuit protecting the transistor element provided as the switching element for controlling an/off action of each of the plurality of pixels,   the protective circuit including the second transistor element formed by using a semiconductor layer containing an amorphous silicon layer and/or a microcrystalline silicon layer.   
     
     
         15 . A display device including a circuit board as set forth in  claim 1 . 
     
     
         16 . The circuit board as set forth in  claim 9 , wherein the oxide semiconductor layer is made of an oxide layer containing at least one element selected from the group consisting of In, Ga, and Zn. 
     
     
         17 . The circuit board as set forth in  claim 12 , wherein the oxide semiconductor layer is made of an oxide layer containing at least one element selected from the group consisting of In, Ga, and Zn. 
     
     
         18 . The circuit board as set forth in  claim 13 , wherein the oxide semiconductor layer is made of an oxide layer containing at least one element selected from the group consisting of In, Ga, and Zn.