Process to make metal oxide thin film transistor array with etch stopping layer

Abstract

The present invention generally relates to thin film transistors (TFTs) and methods of making TFTs. The active channel of the TFT may comprise one or more metals selected from the group consisting of zinc, gallium, tin, indium, and cadmium. The active channel may also comprise nitrogen and oxygen. To protect the active channel during source-drain electrode patterning, an etch stop layer may be deposited over the active layer. The etch stop layer prevents the active channel from being exposed to the plasma used to define the source and drain electrodes. The etch stop layer and the source and drain electrodes may be used as a mask when wet etching the active material layer that is used for the active channel.

1 . A thin film transistor, comprising:
 a gate electrode disposed over a substrate;   a gate dielectric layer disposed over the gate electrode;   a semiconductor layer disposed over the gate dielectric layer, the semiconductor layer comprising oxygen, nitrogen, and one or more elements selected from the group consisting of zinc, gallium, indium, cadmium, and tin;   a source electrode;   a drain electrode; and   an etch stop layer disposed over the semiconductor layer and between the source electrode and the drain electrode.   
     
     
         2 . The thin film transistor of  claim 1 , wherein the etch stop layer is selected from the group consisting of silicon nitride, silicon oxide and combinations thereof. 
     
     
         3 . The thin film transistor of  claim 1 , wherein the semiconductor layer comprises a dopant selected from the group consisting of Al, Sn, Ga, Ca, Si, Ti, Cu, Ge, In, Ni, Mn, Cr, V, Mg, Si x N y , Al x O y , SiC, and combinations thereof. 
     
     
         4 . The thin film transistor of  claim 1 , wherein the semiconductor layer comprises indium, gallium, zinc, oxygen and nitrogen. 
     
     
         5 . The thin film transistor of  claim 1 , wherein the semiconductor layer comprises zinc, oxygen and nitrogen. 
     
     
         6 . The thin film transistor of  claim 1 , wherein the semiconductor layer comprises zinc, tin, oxygen and nitrogen. 
     
     
         7 . A thin film transistor, comprising:
 a gate electrode disposed over a substrate;   a gate dielectric layer disposed over the gate electrode;   a semiconductor layer disposed over the gate dielectric layer, the semiconductor layer comprising an oxynitride compound comprising oxygen, nitrogen, and one or more elements selected from the group consisting of zinc, gallium, indium, cadmium, and tin;   a source electrode;   a drain electrode; and   an etch stop layer disposed over the semiconductor layer and between the source electrode and the drain electrode.   
     
     
         8 . The thin film transistor of  claim 7 , wherein the etch stop layer is selected from the group consisting of silicon nitride, silicon oxide and combinations thereof. 
     
     
         9 . The thin film transistor of  claim 7 , wherein the oxynitride comprises a dopant selected from the group consisting of AI, Sn, Ga, Ca, Si, Ti, Cu, Ge, In, Ni, Mn, Cr, V, Mg, Si x N y , Al x O y , SiC, and combinations thereof. 
     
     
         10 . The thin film transistor of  claim 7 , wherein the oxynitride compound comprises indium, gallium, zinc, oxygen and nitrogen. 
     
     
         11 . The thin film transistor of  claim 7 , wherein the oxynitride compound comprises zinc, oxygen and nitrogen. 
     
     
         12 . The thin film transistor of  claim 7 , wherein the oxynitride compound comprises zinc, tin, oxygen and nitrogen. 
     
     
         13 . A thin film transistor, comprising:
 a gate electrode disposed over a substrate;   a gate dielectric layer disposed over the gate electrode;   a semiconductor layer disposed over the gate dielectric layer, the semiconductor layer comprising oxygen and one or more elements selected from the group consisting of zinc, gallium, indium, cadmium, and tin;   a source electrode;   a drain electrode; and   an etch stop layer disposed over the semiconductor layer and between the source electrode and the drain electrode.   
     
     
         14 . The thin film transistor of  claim 13 , wherein the etch stop layer is selected from the group consisting of silicon nitride, silicon oxide and combinations thereof. 
     
     
         15 . The thin film transistor of  claim 13 , wherein the semiconductor layer comprises a dopant selected from the group consisting of Al, Sn, Ga, Ca, Si, Ti, Cu, Ge, In, Ni, Mn, Cr, V, Mg, Si x N y , Al x O y , SiC, and combinations thereof. 
     
     
         16 . The thin film transistor of  claim 13 , wherein the semiconductor layer comprises indium, gallium, zinc and oxygen. 
     
     
         17 . The thin film transistor of  claim 13 , wherein the semiconductor layer comprises zinc and oxygen.