Semiconductor circuit for electro-optical device and method of manufacturing the same

Abstract

In a monolithic active matrix circuit formed on a substrate, the active regions of at least a part of the thin film transistors (TFTs) constituting the peripheral circuit for driving the matrix region are added with a metal element for promoting the crystallization of silicon at a concentration of 1×10 16 to 5×10 19 cm −3 , no metal element is added to the active region of the TFTs for the matrix region. The channel forming regions of at least a part of the TFTs constituting the peripheral circuit and the channel forming regions of the TFTs for the matrix region are formed by a silicon semiconductor thin film having a monodomain structure.

1 . A display device comprising:
 a display portion comprising a plurality of pixels formed over a substrate; and   a driver circuit formed over the substrate, the driver circuit comprising an inverter,   wherein the inverter comprises an enhancement-type n-channel thin film transistor and a depletion-type n-channel thin film transistor,   wherein a gate of the depletion-type n-channel thin film transistor is electrically connected to one of a source and a drain of the depletion-type n-channel thin film transistor, and   wherein the one of the source and the drain of the depletion-type n-channel thin film transistor is electrically connected to one of a source and a drain of the enhancement-type n-channel thin film transistor.   
     
     
         2 . The display device according to  claim 1 , wherein the depletion-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer containing a metal element at a concentration of 1×10 16  to 5×10 19  cm −3 . 
     
     
         3 . The display device according to  claim 1 , wherein each of the enhancement-type n-channel thin film transistor and the depletion-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer comprising silicon. 
     
     
         4 . The display device according to  claim 1 , wherein the display device is a liquid crystal device. 
     
     
         5 . The display device according to  claim 1 ,
 wherein the depletion-type n-channel thin film transistor comprises a semiconductor layer, and   wherein the semiconductor layer is formed in a monodomain region which contains no grain boundary.   
     
     
         6 . A display device comprising:
 a display portion comprising a plurality of pixels formed over a substrate; and   a driver circuit formed over the substrate, the driver circuit comprising an inverter,   wherein the inverter comprises a first enhancement-type n-channel thin film transistor and a second enhancement-type n-channel thin film transistor,   wherein a gate of the first enhancement-type n-channel thin film transistor is electrically connected to one of a source and a drain of the first enhancement-type n-channel thin film transistor, and   wherein the other one of the source and the drain of the first enhancement-type n-channel thin film transistor is electrically connected to one of a source and a drain of the second enhancement-type n-channel thin film transistor.   
     
     
         7 . The display device according to  claim 6 , wherein the first enhancement-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer containing a metal element at a concentration of 1×10 16  to 5×10 19  cm −3 . 
     
     
         8 . The display device according to  claim 6 , wherein each of the first enhancement-type n-channel thin film transistor and a second enhancement-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer comprising silicon. 
     
     
         9 . The display device according to  claim 6 , wherein the display device is a liquid crystal device. 
     
     
         10 . The display device according to  claim 6 .
 wherein the first enhancement-type n-channel thin film transistor comprises a semiconductor layer, and   wherein the semiconductor layer is formed in a monodomain region which contains no grain boundary.   
     
     
         11 . A display device comprising:
 a first thin film transistor over a substrate;   a pixel electrode electrically connected to the first thin film transistor; and   a driver circuit formed over the substrate, the driver circuit comprising an inverter,   wherein the inverter comprises an enhancement-type n-channel thin film transistor and a depletion-type n-channel thin film transistor,   wherein a gate of the depletion-type n-channel thin film transistor is electrically connected to one of a source and a drain of the depletion-type n-channel thin film transistor, and   wherein the one of the source and the drain of the depletion-type n-channel thin film transistor is electrically connected to one of a source and a drain of the enhancement-type n-channel thin film transistor.   
     
     
         12 . The display device according to  claim 11 , wherein the depletion-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer containing a metal element at a concentration of 1×10 16  to 5×10 19  cm −3 . 
     
     
         13 . The display device according to  claim 11 , wherein each of the enhancement-type n-channel thin film transistor and the depletion-type n-channel thin film transistor comprises a semiconductor layer, the semiconductor layer comprising silicon. 
     
     
         14 . The display device according to  claim 11 , wherein the display device is a liquid crystal device. 
     
     
         15 . The display device according to  claim 11 ,
 wherein the depletion-type n-channel thin film transistor comprises a semiconductor layer, and   wherein the semiconductor layer is formed in a monodomain region which contains no grain boundary.