Liquid crystal display device

1. A liquid crystal display device comprising a pixel electrode in an area surrounded by scan lines extending in a first direction and arranged in a second direction and by image signal lines extending in the second direction and arranged in the first direction,

wherein the pixel electrode is supplied with an image signal from the image signal line through a TFT,

wherein the TFT includes a semiconductor layer having a channel portion, a drain portion formed on the side of the image signal line, and a source portion formed on the side of the pixel electrode,

wherein a gate insulating film is formed so as to cover the semiconductor layer,

wherein a gate electrode is formed on the gate insulating film above the channel portion,

wherein a first interlayer insulating film is formed so as to cover the gate electrode,

wherein the image signal line is provided on the first interlayer insulating film,

wherein an organic film is formed to cover the image signal line,

wherein a common electrode, which is a transparent electrode, is formed on the organic film,

wherein a second interlayer insulating film is formed on the common electrode,

wherein the pixel electrode, which is a transparent electrode, having a slit is formed on the second interlayer insulating film,

wherein a portion of the image signal line connected to the drain portion of the TFT has a width which is greater than a width of an other portion of the image signal line,

wherein the image signal line is connected in the greater width portion to the drain portion through a contact hole,

wherein a through hole is formed in the second interlayer insulating film in the greater width portion of the image signal line, and

wherein the diameter of the through hole is greater than the diameter of the contact hole.

2. The liquid crystal display device according to claim 1 ,

wherein the TFT includes a first TFT and a second TFT,

wherein the first TFT has a drain portion connected to the image signal line,

wherein the second TFT is connected to the first TFT and has a source portion connected to the pixel electrode, and

wherein the scan line also functions as the gate electrodes of the first TFT and the second TFT.

3. The liquid crystal display device according to claim 1 , wherein the through hole formed in the second interlayer insulating film is not covered by the transparent electrode.

4. A liquid crystal display device comprising a pixel electrode formed in an area surrounded by scan lines extending in a first direction and arranged in a second direction and by image signal lines extending in the second direction and arranged in the first direction,

wherein the pixel electrode is supplied with an image signal from the image signal line through a TFT,

wherein the TFT includes a semiconductor layer having a channel portion, a drain portion formed on the side of the image signal line, and a source portion formed on the side of the pixel electrode,

wherein a gate insulating film is formed so as to cover the semiconductor layer,

wherein a gate electrode is formed on the gate insulating film above the channel portion,

wherein a first interlayer insulating film is formed so as to cover the gate electrode,

wherein the image signal line is provided on the first interlayer insulating film,

wherein an organic film is formed to cover the image signal line,

wherein one of the pixel electrode and a common electrode, which is a transparent electrode, is formed on the organic film,

wherein a second interlayer insulating film is formed on the one of the pixel electrode and the common electrode,

wherein an other of the pixel electrode and the common electrode, which is a transparent electrode, having a slit is formed on the second interlayer insulating film,

wherein a portion of the image signal line connected to the drain portion of the TFT has a width which is greater than a width of an other portion of the image signal line,

wherein the image signal line is connected in the greater width portion to the drain portion through a contact hole,

wherein a through hole is formed in the second interlayer insulating film in the greater width portion of the image signal line, and

wherein the diameter of the through hole is greater than the diameter of the contact hole.

5. The liquid crystal display device according to claim 4 ,

wherein the TFT includes a first TFT and a second TFT,

wherein the first TFT has a drain portion connected to the image signal line,

wherein the second TFT is connected to the first TFT and has a source portion connected to the pixel electrode, and

wherein the scan line also functions as the gate electrodes of the first TFT and the second TFT.

6. The liquid crystal display device according to claim 4 , wherein the through hole formed in the second interlayer insulating film is not covered by the transparent electrode.

7. A liquid crystal display device comprising a display area and a peripheral circuit portion,

wherein the peripheral circuit portion includes a TFT including a semiconductor layer having a channel portion, a source portion, and a drain portion,

wherein a gate insulating film is formed so as to cover the semiconductor layer,

wherein a gate electrode is formed on the gate insulating film above the channel portion,

wherein a first interlayer insulating film is formed so as to cover the gate electrode,

wherein a metal line is formed on the first interlayer insulating film,

wherein the metal line is connected to the drain portion or the source portion through a contact hole formed in the first interlayer insulating film and in the gate insulating film,

wherein an organic film is formed to cover the metal line,

wherein a line of ITO is formed on the organic film,

wherein a second interlayer insulting film is formed on the ITO line,

wherein a through hole is formed in the second interlayer insulating film, and

wherein the diameter of the through hole is greater than the diameter of the contact hole.

8. The liquid crystal display device according to claim 7 , wherein the through hole formed in the second interlayer insulating film is not covered by ITO.

9. A liquid crystal display device comprising a TFT substrate and a counter substrate,

wherein the TFT substrate and the counter substrate are bonded face-to-face with a liquid crystal layer formed inside,

wherein a terminal portion and an alignment mark are formed in a portion of the TFT substrate not facing the counter substrate,

wherein the alignment mark is configured such that a gate insulating film, a first interlayer insulating film, and an organic film are laminated in this order on the TFT substrate,

wherein a transparent electrode is formed on the organic film,

wherein a second interlayer insulating film is formed on the transparent electrode, and

wherein a through hole is formed in the second interlayer insulating film in an area in which the alignment mark is formed.

10. The liquid crystal display device according to claim 9 , wherein the through hole formed in the second interlayer insulating film is not covered by the transparent electrode.

11. The liquid crystal display device according to claim 4 , wherein the one of the pixel electrode and the common electrode is the pixel electrode, and the other of the pixel electrode and the common electrode is the common electrode.