Active matrix LCD device with image signal lines having a multilayered structure

Abstract

A liquid crystal display device and a manufacturing method therefor are provided where the number of processes for manufacturing TFT substrates can be decreased and a high production yield can be attained. To attain these objects, an image signal bus-line includes at least a transparent conductive film and a semiconductor layer. A pattern of the transparent conductive film extends up to a thin film transistor to form its drain electrode, and a pattern of a semiconductor layer extends up to the transistor to form its source electrode. By virtue of these arrangements, the thin film transistor substrate can be manufactured using as little as three or four photolithography processes.

1. A liquid crystal display device comprising:
 a substrate;  
 a plurality of scanning signal bus-lines formed on the substrate and extending in a first direction,  
 a plurality of image signal bus-lines formed on the substrate and extending in a second direction intersecting with the scanning signal bus-lines,  
 thin film transistors located adjacent intersecting points of the scanning signal bus-lines and the image signal bus-lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus-lines, drain electrodes of the thin film transistors are connected to the image signal bus-lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, wherein: 
 patterns of a semiconductor layer are formed over said substrate along said image signal bus-lines,  
 said image signal bus-lines are formed of a transparent conductive film, a first conductive film, and an impurity containing semiconductor layer,  
 patterns of said transparent conductive film, said first conductive film, and said impurity containing layer of said image signal bus-lines extend up to said drain electrodes, and  
 patterns of said semiconductor layer along said image signal bus-lines extend up to said source electrodes.  
 
 
     
     
       2. A liquid crystal display device comprising:
 a substrate;  
 a plurality of scanning signal bus-lines formed on the substrate,  
 a plurality of image signal bus-lines formed on the substrate so as to intersect with the scanning signal bus-lines,  
 thin film transistors located adjacent intersecting points of the scanning signal bus-lines and the image signal bus-lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus-lines, drain electrodes of the thin film transistors are connected to the image signal bus-lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, wherein: 
 patterns of a semiconductor layer are formed over said substrate along said image signal bus-lines,  
 said image signal bus-lines comprise a transparent conductive film, a silicide film, and an impurity containing semiconductor layer,  
 patterns of said transparent conductive film, said silicide film, and said impurity containing layer of said image signal bus-lines extend up to said drain electrodes, and  
 patterns of said semiconductor layer along said image signal bus-lines extend up to said source electrodes.  
 
 
     
     
       3. A liquid crystal display device comprising:
 a substrate,  
 a plurality of scanning signal bus-lines formed on the substrate,  
 a plurality of image signal bus-lines formed on the substrate so as to intersect with the scanning signal bus-lines,  
 thin film transistors located adjacent intersecting points of the scanning signal bus-lines and the image signal bus-lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus-lines, drain electrodes of the thin film transistors are connected to the image signal bus-lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, wherein: 
 patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus-lines,  
 said image signal bus-lines are formed of a transparent conductive film, a first conductive layer or a silicide film, an impurity containing semiconductor layer, and a conductive layer,  
 patterns of said transparent conductive film, said first conductive layer or said silicide film, and said impurity containing semiconductor layer extend up to said drain electrodes,  
 patterns of said semiconductor layer and said insulator layer extend up to said source electrodes, and  
 island shape patterns of said conductive layer are formed between the adjacent scanning signal bus-lines, wherein said transparent conductive film of said image signal bus-lines and said conductive layer sandwich at least said insulator layer and said semiconductor layer, and are electrically connected to each other.  
 
 
     
     
       4. A liquid crystal display device according to  claim 1 ,  2  or  3 , wherein said first conductive film or said silicide film is located between said impurity containing semiconductor layer and said transparent conductive layer. 
     
     
       5. A liquid crystal display device according to  claim 4 , wherein an inclining angle of pattern edge surfaces of said semiconductor layer is not larger than that of pattern edge surfaces of said insulator layer. 
     
     
       6. A liquid crystal display device according to  claim 1 ,  2  or  3 , wherein each of said pixel electrodes is formed of a transparent conductive film, said transparent conductive film being formed of a same layer as of said transparent conductive film of said image signal bus-lines, and patterns of said pixel electrodes extend up to said source electrodes. 
     
     
       7. A liquid crystal display device according to  claim 1 ,  2  or  3 , wherein said first conductive film is formed of Mo, Cr, Ti, Ta, W, or a composite of these, or said silicide film is MoSi x , CrSi x , TiSi x , TaSi x , WSi x , or a composite of these. 
     
     
       8. A liquid crystal display device according to  claim 1 ,  2  or  3 , wherein said thin film transistors are arranged in a reverse stagger structure. 
     
     
       9. A liquid crystal display device according to  claim 1 ,  2  or  3 , wherein said scanning signal bus-lines are coated with an anodic oxide film. 
     
     
       10. A liquid crystal display device comprising:
 a substrate,  
 a plurality of scanning signal bus-lines formed on the substrate,  
 a plurality of image signal bus-lines formed on the substrate so as to intersect with the scanning signal bus-lines,  
 thin film transistors located adjacent intersecting points of the scanning signal bus-lines and the image signal bus-lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus-lines, drain electrodes of the thin film transistors are connected to the image signal bus-lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, wherein: 
 patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus-lines,  
 said image signal bus-lines are formed of a transparent conductive film, a first conductive layer or a silicide film, an impurity containing semiconductor layer, and a conductive layer,  
 patterns of said transparent conductive film, said first conductive layer or said silicide film, and said impurity containing semiconductor layer extend up to said drain electrodes,  
 patterns of said semiconductor layer and said insulator layer extend up to said source electrodes, and  
 island shape patterns of said conductive layer are formed between the adjacent scanning signal bus-lines, wherein said transparent conductive film of said image signal bus-lines and said conductive layer sandwich at least said insulator layer and said semiconductor layer, and are electrically connected to each other.  
 
 
     
     
       11. A method of manufacturing a liquid crystal display device comprising a thin film transistor substrate, wherein the method of manufacturing the thin film transistor substrate comprises:
 patterning a conductive film to form scanning signal bus-lines and gate electrodes on the substrate by means of a first photo-treatment process;  
 successively forming a gate insulating layer, a semiconductor layer, and an impurity containing semiconductor layer on the substrate, the scanning signal bus-lines and the gate electrodes;  
 successively patterning the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer by means of a second photo-treatment process, wherein patterns of the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer have substantially an identical pattern;  
 forming a first metal layer, forming a silicide film by heat-reacting the first metal layer with semiconductor material, and then etching a non-reacted portion of the first metal layer without a mask;  
 forming a transparent conductive film;  
 patterning the transparent conductive film to form image signal bus-lines, pixel electrodes, the drain electrodes and the source electrodes by means of a third photo-treatment process, wherein patterns of the transparent conductive film extend from the image signal bus-lines to the drain electrodes, and from the pixel electrodes to the source electrodes, respectively; and  
 etching the silicide film and the impurity containing semiconductor layer with the patterns of the transparent conductive film as a mask wherein the outer edges of the patterns of the silicide film, the impurity containing semiconductor layer, and the transparent conductive layer in the thin film transistors have substantially an identical pattern.  
 
     
     
       12. A method of manufacturing a liquid crystal display device comprising a thin film transistor substrate, wherein the method of manufacturing the thin film transistor substrate comprises:
 patterning a conductive film to form scanning signal bus-lines and gate electrodes on the substrate by means of a first photo-treatment process;  
 successively forming a gate insulating layer, a semiconductor layer, an impurity containing semiconductor layer, and a first metal layer on the substrate, the scanning signal bus-lines and the gate electrodes;  
 forming a silicide film by heat-reacting the first metal layer with the impurity containing semiconductor layer;  
 successively patterning the first metal layer, the silicide film, the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer by means of a second photo-treatment process, and then etching a non-reacted portion of the first metal layer without a mask, wherein patterns of the silicide layer, the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer have substantially an identical pattern;  
 forming a transparent conductive film;  
 patterning the transparent conductive film to form image signal bus-lines, pixel electrodes, the drain electrodes and the source electrodes by means of a third photo-treatment process, wherein patterns of the transparent conductive film extend from the image signal bus-lines to the drain electrodes, and from the pixel electrodes to the source electrodes, respectively; and  
 etching the silicide film and the impurity containing semiconductor layer with the patterns of the transparent conductive film as a mask, wherein the outer edges of the patterns of the silicide film, the impurity containing semiconductor layer, and the transparent layer in the thin film transistors have substantially an identical pattern.  
 
     
     
       13. A method of manufacturing a liquid crystal display device comprising a thin film transistor substrate, wherein the method of manufacturing the thin film transistor substrate comprises:
 patterning a conductive film to form scanning signal bus-lines and gate electrodes on the substrate by means of a first photo-treatment process;  
 successively forming a gate insulating layer, a semiconductor layer, an impurity containing semiconductor layer, and a first metal layer on the substrate, the scanning signal bus-lines and the gate electrodes;  
 successively patterning the first metal layer, the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer by means of a second photo-treatment process, wherein patterns of the first metal layer, the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer have substantially an identical pattern;  
 forming a transparent conductive film;  
 patterning the transparent conductive film to form the image signal bus-lines, pixel electrodes, the drain electrodes and the source electrodes by means of a third photo-treatment process, wherein patterns of the transparent conductive film extend from the image signal bus-lines to the drain electrodes, and from the pixel electrodes to the source electrodes, respectively; and  
 etching the first metal layer with the patterns of the transparent conductive film as a mask; and  
 etching the impurity containing semiconductor layer with the patterns of the transparent conductive film as a mask, wherein the outer edges of the patterns of the first metal layer, the impurity containing semiconductor layer, and the transparent conductive layer in the thin film transistors have substantially an identical pattern.  
 
     
     
       14. A method of manufacturing a liquid crystal display device according to claims  11 ,  12  or  13 , the method further comprising:
 dry etching the impurity containing semiconductor layer, the semiconductor layer, and the gate insulating layer, and wet etching the conductive film, the first conductive layer, and the transparent conductive layer.  
 
     
     
       15. A method of manufacturing a liquid crystal display device according to claims  11 ,  12  or  13 , the method comprising further anodizing upper and end side surfaces of the conductive film after patterning. 
     
     
       16. A method of manufacturing a liquid crystal display device according to claims  11 ,  12  or  13 , the method further comprising:
 forming a protecting film and patterning the protecting film by means of a fourth photo-treatment process, wherein the patterns of the protecting film are in an area excluding at least central portions of the pixel electrodes, terminal portions connecting to an external circuit in end portions of the scanning signal bus-lines and terminal portions connecting to an external circuit in end portions of the image signal bus-lines.  
 
     
     
       17. A method of manufacturing a liquid crystal display device according to claims  11 ,  12  or  13 , the method comprising:
 further patterning a conductive film to form island shape patterns between the scanning signal bus-lines by means of a photo-treatment process; and  
 further patterning the transparent conductive film,  
 wherein patterns of the transparent conductive film of the image signal bus-lines are electrically connected to the island shape patterns.  
 
     
     
       18. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate and extending in a first direction;        a plurality of image signal bus - lines formed on the substrate and extending in a second direction intersecting with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, and wherein:      patterns of a semiconductor layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first metal film, and a transparent conductive film formed over the first metal film;        said image signal bus - lines are connected to the drain electrodes of the thin film transistors extending in the second direction;        patterns of said transparent conductive film, said first metal film, and said impurity containing layer of said image signal bus - lines extend up to said drain electrodes; and        patterns of said semiconductor layer along said image signal bus - lines extend up to said source electrodes.       
     
     
       19. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, and wherein:      patterns of a semiconductor layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a silicide film, and a transparent conductive film formed over the silicide film;        said image signal bus - lines are connected to the drain electrodes of the thin film transistors extending in the second direction;        patterns of said transparent conductive film, said silicide film, and said impurity containing layer of said image signal bus - lines extend up to said drain electrodes;        and patterns of said semiconductor layer along said image signal bus - lines extend up to said source electrodes.       
     
     
       20. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of a transparent conductive film, a first conductive layer or a silicide film, an impurity containing semiconductor layer, and a conductive layer;        patterns of said transparent conductive film, said first conductive layer or said silicide film, and said impurity containing semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        island shape patterns of said conductive layer are formed between the adjacent scanning signal bus - lines, wherein said transparent conductive film of said image signal bus - lines and said conductive layer sandwich at least said insulator layer and said semiconductor layer, and are electrically connected to each other.       
     
     
       21. A liquid crystal display device according to  claim 18 ,  19  or  20 , wherein said first conductive film or said silicide film is located between said impurity containing semiconductor layer and said transparent conductive layer. 
     
     
       22. A liquid crystal display device according to  claim 21 , wherein an inclining angle of pattern edge surfaces of said semiconductor layer is not larger than that of pattern edge surfaces of said insulator layer. 
     
     
       23. A liquid crystal display device according to  claim 18 ,  19  or  20 , wherein each of said pixel electrodes is formed of a transparent conductive film, said transparent conductive film being formed of a same layer as of said transparent conductive film of said image signal bus- lines, and patterns of said pixel electrodes extend up to said source electrodes.   
     
     
       24. A liquid crystal display device according to  claim 18 ,  19  or  20 , wherein said first conductive film is formed of Mo, Cr, Ti, Ta, W, or a composite thereof, or said silicide film is MoSiMoSi x   , CrSiMoSi   x   , TiSiMoSi   x   , TaSiMoSi   x   , WSiMoSi   x   , or a composite thereof.   
     
     
       25. A liquid crystal display device according to  claim 18 ,  19  or  20 , wherein said thin film transistors are arranged in a reverse stagger structure. 
     
     
       26. A liquid crystal display device according to  claim 18 ,  19  or  20 , wherein said scanning signal bus- lines are coated with an anodic oxide film.   
     
     
       27. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines;        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of gate terminals connected to the scanning signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said gate terminals formed of a second conductive film and a transparent conductive film.       
     
     
       28. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of gate terminals connected to the scanning signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said gate terminals are formed of a second conductive film and a transparent conductive film formed over the second conductive film.       
     
     
       29. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of gate terminals connected to the scanning signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film formed over the first conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said gate terminals are formed of a second conductive film and a transparent conductive film formed on the second conductive film.       
     
     
       30. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of drain terminals connected to the image signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said drain terminals are formed of a second conductive film and a transparent conductive film.       
     
     
       31. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of drain terminals connected to the image signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing said semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said drain terminals are formed of a second conductive film and a transparent conductive film formed over said second conductive film.       
     
     
       32. A liquid crystal display device comprising:
   a substrate;        a plurality of scanning signal bus - lines formed on the substrate;        a plurality of image signal bus - lines formed on the substrate so as to intersect with the scanning signal bus - lines; and        thin film transistors located adjacent intersecting points of the scanning signal bus - lines and the image signal bus - lines, wherein gate electrodes of the thin film transistors are connected to the scanning bus - lines, drain electrodes of the thin film transistors are connected to the image signal bus - lines, and source electrodes of the thin film transistors are connected to pixel electrodes to drive a liquid crystal provided in said display, a plurality of drain terminals connected to the image signal bus - lines, and wherein:      patterns of a semiconductor layer and an insulator layer are formed over said substrate along said image signal bus - lines;        said image signal bus - lines are formed of an impurity containing semiconductor layer, a first conductive film, and a transparent conductive film formed over said first conductive film;        patterns of said transparent conductive film, said first conductive film, and said impurity containing said semiconductor layer extend up to said drain electrodes;        patterns of said semiconductor layer and said insulator layer extend up to said source electrodes; and        said drain terminals are formed of a second conductive film and a transparent conductive film formed on said second conductive film.