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 display device, comprising:
 a substrate;   a gate line provided over the substrate;   a source line provided over the substrate so as to cross the gate line; and   a first switching element;   the first switching element comprising:   a gate electrode electrically connected to the gate line;   a gate insulating layer contacted to the gate electrode;   an active layer contacted to the gate insulating layer, the gate insulating layer being disposed between the gate electrode and the active layer, the active layer containing group III elements, group IV elements, or group V elements, and being made of a semiconductor containing (i) polycrystalline ZnO or polycrystalline Mg x Zn 1−x O, (ii) amorphous ZnO or amorphous Mg x Zn 1−x O, or (iii) either (a) mixture of the polycrystalline ZnO and the amorphous ZnO or (b) a mixture of the polycrystalline Mg x Zn 1−x O and the amorphous Mg x Zn 1−x O;   a source electrode and a drain electrode electrically contacted to the active layer, the source electrode being electrically connected to the source line; and   a protective layer provided over the active layer, the source electrode and the drain electrode.   
     
     
         2 . The display device as set forth in  claim 1 , further comprising:
 a gate driver which is provided over the substrate and to which the gate line is electrically connected,   the gate driver including a second switching element connected to the gate line, the second switching element having a same configuration as the first switching element.   
     
     
         3 . The display device as set forth in  claim 2 , further comprising:
 a source driver which is provided over the substrate and to which the source line is electrically connected,   the source driver including a third switching element electrically connected to the source line, the third switching element having a same configuration as the first switching element.   
     
     
         4 . The display device as set. forth in  claim 3 , further comprising:
 a power supply circuit for supplying a power supply voltage to the gate driver and the source driver.   
     
     
         5 . The display device as set forth in  claim 1 , further comprising:
 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,   the gate electrode being configured to control move of the movable electric charges in the active layer,   the gate insulating layer serving as one of the plurality of blocking layers and insulating the gate electrode from the active layer;   the source electrode and the drain electrode serving as others of the plurality of blocking layers and being connected to the active layer; and   the rest of the plurality of blocking layers, except the source electrode and the drain electrode and the gate insulating layer, being made of SiO 2 , Al 2 O 3 , AlN, 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  represented by (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.