Semiconductor device, manufacturing method thereof, and electronic device

Abstract

In a thin film transistor, a gate insulating layer is formed on a gate electrode formed on an insulating substrate. Formed on the gate insulating layer is a semiconductor layer. Formed on the semiconductor layer are a source electrode and a drain electrode. A protective layer covers them, so that the semiconductor layer is blocked from an atmosphere. The semiconductor layer (active layer) is made of, e.g., a semiconductor containing polycrystalline ZnO to which, e.g., a group V element is added. This allows practical use of a semiconductor device which has an active layer made of zinc oxide and which includes an protective layer for blocking the active layer from an atmosphere.

1 . A semiconductor device comprising:
 an active layer, to which group I elements, group III elements, group IV elements, group V elements, or group VII elements are added, and which is made of a semiconductor containing (i) polycrystalline ZnO or polycrystalline MgxZn1-xO, (ii) amorphous ZnO or amorphous MgxZn1-xO, or (iii) either (a) mixture of the polycrystalline ZnO and the amorphous ZnO or (b) a mixture of the polycrystalline MgxZn1-xO and the amorphous MgxZn1-xO;   a blocking member made of a plurality of blocking layers for blocking a region of the active layer from an atmosphere in which region movable electric charges move;   a gate electrode for controlling movement of the movable electric charges in the active layer;   a gate insulating layer, which serves as one of the plurality of blocking layers, for insulating the active layer from the gate electrode;   a source electrode serving as one of the plurality of blocking layers, the source electrode being connected to the active layer; and   a drain electrode serving as one of the plurality of blocking layers, the drain electrode being connected to the active layer,   at least one of the plurality of blocking layers, in addition to the source electrode and the drain electrode and the gate insulating layer, each of the at least one of the plurality of blocking layers being made of SiO 2 , Al 2 O 3 , AIN, MgO, Ta 2 O 5 , TiO 2 , ZrO 2 , stab-ZrO 2 , CeO 2 , K 2 O, Li 2 O, Na 2 O, Rb 2 O, In 2 O 3 , La 2 O 3 , Sc 2 O 3 , Y 2 O 3 , KNbO 3 , KTaO 3 , BaTiO 3 , CaSnO 3 , CaZrO 3 , CdSnO 3 , SrHfO 3 , SrSnO 3 , SrTiO 3 , YScO 3 , CaHfO 3 , MgCeO 3 , SrCeO 3 , BaCeO 3 , SrZrO 3 , BaZrO 3 , LiGaO 2 , a mixed crystal of LiGaO 2  such as (Li 1-(x+y) Na x K y )(Ga 1-z Al z )O 2 , or a solid solution containing at least two of them.   
     
     
         2 . The semiconductor device as set forth in  claim 1 , wherein:
 the gate insulating layer is made of SiO 2 , Al 2 O 3 , AIN, MgO, Ta 2 O 5 , TiO 2 , ZrO 2 , stab-ZrO 2 , CeO 2 , K 2 O, Li 2 O, Na 2 O, Rb 2 O,  1 n 2 O 3 , La 2 O 3 , Sc 2 O 3 , Y 2 O 3 , KNbO 3 , KTaO 3 , BaTiO 3 , CaSnO 3 , CaZrO 3 , CdSnO 3 , SrHfO 3 , SrSnO 3 , SrTiO 3 , YScO 3 , CaHfO 3 , MgCeO 3 , SrCeO 3 , BaCeO 3 , SrZrO 3 , BaZrO 3 , LiGaO 2 , a mixed crystal of LiGaO 2  such as (Li 1-(x+y) Na x K y )(Ga 1-z Al z )O 2 , or a solid solution containing at least two of them.   
     
     
         3 . The semiconductor device as set forth in  claim 1 , wherein:
 each of the source electrode and the drain electrode serving as the blocking layers are present in a layer below the active layer.   
     
     
         4 . The semiconductor device as set forth in  claim 1 , wherein:
 each of the source electrode and the drain electrode serving as the blocking layers are present in a layer above the active layer.   
     
     
         5 . The semiconductor device as set forth in  claim 2 , wherein:
 each of the source electrode and the drain electrode serving as the blocking layers are present in a layer below the active layer.   
     
     
         6 . The semiconductor device as set forth in  claim 2 , wherein:
 each of the source electrode and the drain electrode serving as the blocking layers are present in a layer above the active layer.   
     
     
         7 . An electronic device comprising the semiconductor device as set forth in any one of  claims 1  to  6 , provided as a switching element. 
     
     
         8 . The electronics device as set forth in  claim 7 , wherein:
 the switching element is connected to a picture element electrode for writing an image signal to the picture element electrode or for reading an image signal from the picture element electrode.