Method for manufacturing an electrooptical device

Abstract

An object of the present invention is to provide an electrooptical device having high operation performance and reliability, and a method of manufacturing the electrooptical device. Lov region 207 is disposed in n-channel TFT 302 that comprises a driver circuit, and a TFT structure which is resistant to hot carriers is realized. Loff regions 217 to 220 are disposed in n-channel TFT 304 that comprises a pixel section, and a TFT structure of low off current is realized. An input-output signal wiring 305 and gate wiring 306 are formed by laminating a first wiring and a second wiring having lower resistivity than the first wiring, and wiring resistivity is steeply reduced.

1 . (canceled) 
     
     
         2 . A display device comprising:
 a crystalline silicon film over a substrate, the crystalline silicon film comprising:
 a first impurity region; 
 a second impurity region; 
 a third impurity region between the first impurity region and the second impurity region; 
 a first channel forming region between the first impurity region and the third impurity region; 
 a second channel forming region between the second impurity region and the third impurity region; and 
 a fourth impurity region between the second channel forming region and the second impurity region, the fourth impurity region containing impurities at lower concentration than the second impurity region; 
   a first wiring over the first impurity region, the first wiring being electrically connected to the first impurity region;   a second wiring over the second impurity region, the second wiring being electrically connected to the second impurity region;   a pixel electrode over the second wiring, the pixel electrode being electrically connected to the second wiring; and   a first electrode under the pixel electrode with an insulating film interposed therebetween,   wherein the first wiring overlaps the first channel forming region,   wherein the second wiring overlaps the fourth impurity region, and   wherein the pixel electrode overlaps the fourth impurity region.   
     
     
         3 . The display device according to  claim 2 ,
 wherein the first electrode is a shielding film.   
     
     
         4 . The display device according to  claim 2 ,
 wherein the insulating film is anodic oxide film.   
     
     
         5 . The display device according to  claim 2 ,
 wherein the crystalline silicon film is a polycrystalline silicon film.   
     
     
         6 . A display device comprising:
 a crystalline silicon film over a substrate, the crystalline silicon film comprising:
 a first impurity region; 
 a second impurity region; 
 a third impurity region between the first impurity region and the second impurity region; 
 a first channel forming region between the first impurity region and the third impurity region; 
 a second channel forming region between the second impurity region and the third impurity region; and 
 a fourth impurity region between the second channel forming region and the second impurity region, the fourth impurity region containing impurities at lower concentration than the second impurity region; 
   a first wiring over the first impurity region, the first wiring being electrically connected to the first impurity region;   a second wiring over the second impurity region, the second wiring being electrically connected to the second impurity region;   a pixel electrode over the second wiring, the pixel electrode being electrically connected to the second wiring;   a liquid crystal material over the pixel electrode; and   a first electrode under the pixel electrode with an insulating film interposed therebetween,   wherein the first wiring overlaps the first channel forming region,   wherein the second wiring overlaps the fourth impurity region, and   wherein the pixel electrode overlaps the fourth impurity region.   
     
     
         7 . The display device according to  claim 6 ,
 wherein the first electrode is a shielding film.   
     
     
         8 . The display device according to  claim 6 ,
 wherein the insulating film is anodic oxide film.   
     
     
         9 . The display device according to  claim 6 , further comprising an opposing electrode over the liquid crystal material. 
     
     
         10 . The display device according to  claim 6 ,
 wherein the crystalline silicon film is a polycrystalline silicon film.   
     
     
         11 . A display device comprising:
 a crystalline silicon film over a substrate, the crystalline silicon film comprising:
 a first impurity region; 
 a second impurity region; 
 a third impurity region between the first impurity region and the second impurity region; 
 a first channel forming region between the first impurity region and the third impurity region; 
 a second channel forming region between the second impurity region and the third impurity region; and 
 a fourth impurity region between the second channel forming region and the second impurity region, the fourth impurity region containing impurities at lower concentration than the second impurity region; 
 a first insulating film over the second channel forming region; 
 a gate electrode over the first insulating film, the gate electrode overlapping the second channel forming region; 
 a second insulating film over the gate electrode; 
 a first wiring over the second insulating film, the first wiring being electrically connected to the first impurity region; 
 a second wiring over the second insulating film, the second wiring being electrically connected to the second impurity region; 
 a third insulating film over the first wiring and the second wiring, the third insulating film comprising a contact hole; 
 a first electrode over the third insulating film; 
 a fourth insulating film over the first electrode; 
 a second electrode over the fourth insulating film, the second electrode being in contact with the second wiring through the contact hole; and 
 a liquid crystal material over the second electrode, 
 wherein the first wiring overlaps the first channel forming region, 
 wherein the second wiring overlaps the fourth impurity region, and 
 wherein the second electrode overlaps the fourth impurity region. 
   
     
     
         12 . The display device according to  claim 11 ,
 wherein the first electrode is a shielding film.   
     
     
         13 . The display device according to  claim 11 ,
 wherein the second electrode is a pixel electrode.   
     
     
         14 . The display device according to  claim 11 , further comprising a third electrode over the liquid crystal material. 
     
     
         15 . The display device according to  claim 14 ,
 wherein the third electrode is an opposing electrode.   
     
     
         16 . The display device according to  claims 11 ,
 wherein the fourth insulating film is anodic oxide film.   
     
     
         17 . The display device according to  claim 11 ,
 wherein the second electrode is in contact with the third insulating film in the contact hole.   
     
     
         18 . The display device according to  claim 11 ,
 wherein the gate electrode does not overlap the fourth impurity region.   
     
     
         19 . The display device according to  claim 11 ,
 wherein the crystalline silicon film is a polycrystalline silicon film.