Liquid Crystal Display Device

Abstract

A liquid crystal display device includes a plurality of pixels, each including a thin-film transistor and a pixel electrode formed above a substrate, and an organic insulation film formed between one electrode of the thin-film transistor and the pixel electrode. The one electrode and the pixel electrode are connected through a contact hole formed in the organic insulation film, and a sidewall of the contact hole, which is made of the organic insulation film, is tapered. An underlying layer beneath the organic insulation film, in contact with to the organic insulation film, includes a lowermost plane extending substantially in parallel to a plane of the substrate and an uppermost plane extending substantially in parallel to the plane of the substrate. A single step of the underlying layer is formed so as to extend between the lowermost plane and the uppermost plane.

What is claimed is: 
     
         1 . A liquid crystal display device comprising a plurality of pixels, each including a thin-film transistor and a pixel electrode formed above a substrate, and an organic insulation film formed between one electrode of the thin-film transistor and the pixel electrode;
 wherein the one electrode and the pixel electrode are connected through a contact hole formed in the organic insulation film;   wherein a sidewall of the contact hole, which is made of the organic insulation film, is tapered;   wherein an underlying layer beneath the organic insulation film, in contact with the organic insulation film, includes a lowermost plane extending substantially in parallel to a plane of the substrate and an uppermost plane extending substantially in parallel to the plane of the substrate;   wherein the lowermost plane overlaps with the sidewall in plan view;   wherein the uppermost plane is at a position farther from the substrate than a position of the lowermost plane from the substrate, and is disposed at a side of the lowermost plane, the side of the lowermost plane being disposed at a position spaced from the sidewall; and   wherein a single step of the underlying layer is formed so as to extend between the lowermost plane and the uppermost plane.   
     
     
         2 . The liquid crystal display device according to  claim 1 , wherein the organic insulation film is a color filter film. 
     
     
         3 . The liquid crystal display device according to  claim 1 , wherein the underlying layer is located above a single line. 
     
     
         4 . The liquid crystal display device according to  claim 3 , wherein the underlying layer is located above a visual signal line. 
     
     
         5 . The liquid crystal display device according to  claim 3 , wherein the underlying layer is located above a scan signal line. 
     
     
         6 . The liquid crystal display device according to  claim 5 , wherein the uppermost plane overlaps with the scan signal line in plan view; and
 wherein the lowermost plane does not overlap with the scan signal line in plan view.   
     
     
         7 . The liquid crystal display device according to  claim 1 , wherein the underlying layer is an inorganic insulating film including silicon nitride of silicon oxide. 
     
     
         8 . The liquid crystal display device according to  claim 1 , wherein the single step is formed by a difference in the number of layers that are formed under the organic insulation film. 
     
     
         9 . The liquid crystal display device according to  claim 1 , wherein a distance from a position at which the sidewall of the organic insulation film of the contact hole intersects with the lowermost plane to an end of the lower most plane abutting the single step is no greater than 1 μm. 
     
     
         10 . A liquid crystal display device comprising a plurality of pixels, each including a thin-film transistor and a pixel electrode formed above a substrate, and a color filter layer formed between one electrode of the thin-film transistor and the pixel electrode;
 wherein the one electrode and the pixel electrode are connected through a contact hole formed in the color filter layer;   wherein a sidewall of the contact hole, which is made of the color filter layer, is tapered;   wherein an underlying layer beneath the color filter layer, in contact with the color filter layer, includes a lowermost plane extending substantially in parallel to a plane of the substrate and an uppermost plane extending substantially in parallel to the plane of the substrate;   wherein the lowermost plane overlaps with the sidewall in plan view;   wherein the uppermost plane is at a position farther from the substrate than a position of the lowermost plane from the substrate, and is disposed at a side of the lowermost plane, the side of the lowermost plane being disposed at a position spaced from the sidewall; and   wherein a single step of the underlying layer is formed so as to extend between the lowermost plane and the uppermost plane.   
     
     
         11 . The liquid crystal display device according to  claim 10 , wherein the underlying layer is located above a visual signal line. 
     
     
         12 . The liquid crystal display device according to  claim 10 , wherein the underlying layer is located above a scan signal line;
 wherein the uppermost plane overlaps with the scan signal line in plan view; and   wherein the lowermost plane does not overlap with the scan signal line in plan view.   
     
     
         13 . The liquid crystal display device according to  claim 10 , wherein a distance from a position at which the sidewall of the color filter layer of the contact hole intersects with the lowermost plane to an end of the lowermost plane abutting the single step is no greater than 1 μm. 
     
     
         14 . The liquid crystal display device according to  claim 10 , wherein the color filter layer includes a first color filter and a second color filter which has a color different from the first color filter;
 wherein a part of the first color filter is superposed on a part of the second color filter;   wherein the underlying includes a first plane and a second plane which is nearer to the substrate than a position of the first plane to the substrate;   wherein the first plane overlaps with an end portion of the second color filter, the end portion being included in the part of the second color filter;   wherein the second plane is disposed at a side of the first plane, the side of the first plane being disposed at a position spaced from the end portion; and   wherein a step is formed so as to extend between the first plane and the second plane.   
     
     
         15 . A liquid crystal display device comprising a plurality of pixels, each including a thin-film transistor and a pixel electrode formed above a substrate, and a color filter layer formed between one electrode of the thin-film transistor and the pixel electrode;
 wherein the one electrode and the pixel electrode are connected through a contact hole formed in the color filter layer;   wherein a sidewall of the contact hole, which is made of the color filter layer, is tapered;   wherein an underlying layer beneath the color filter layer, in contact with the color filter layer, includes a first plane extending substantially in parallel to the plane of the substrate;   wherein the first plane overlaps with the sidewall in plan view;   wherein the second plane is at a position farther from the substrate than a position of the first plane from the substrate, and is disposed at a side of the first plane, the side of the first plane being disposed at a position spaced from the sidewall; and   wherein a first step of the underlying layer is formed so as to extend between the lowermost plane and the uppermost plane.   
     
     
         16 . The liquid crystal display device according to  claim 15 , wherein the color filter layer includes a first color filter and a second color filter which has a color different from the first color filter;
 wherein a part of the first color filter is superposed on a part of the second color filter;   wherein the underlying layer includes a third plane and a fourth plane which is at a position nearer to the substrate than a position of the third plane to the substrate;   wherein the third plane overlaps with an end portion of the second color filter, the end portion being included in the part of the second color filter;   wherein the fourth plane is disposed at a side of the third plane, the side of the third plane being disposed at a position spaced from the end portion; and   wherein a second step is formed so as to extend between the third plane and the fourth plane.   
     
     
         17 . The liquid crystal display device according to  claim 16 , wherein a signal line is located under the third plane. 
     
     
         18 . The liquid crystal display device according to  claim 15 , wherein the underlying layer is located above a scan signal line;
 wherein the first plane overlaps with the scan signal line in plan view; and   wherein the second plane does not overlap with the scan signal line in plan view.   
     
     
         19 . The liquid crystal display device according to  claim 15 , wherein the first step surrounds the contact hole. 
     
     
         20 . The liquid crystal display device according to  claim 15 , wherein a distance from a position at which the sidewall of the color filter layer of the contact hole intersects with the first plane to an end of the first plane abutting the first step is no greater than 1 μm.