Photosensor

Abstract

For a photosensor, an array substrate is provided, wherein the edge of a photodiode is enclosed by the opening edge of a contact hole formed on a drain electrode.

1 . A photosensor comprising:
 a TFT array substrate of active matrix type, on which a photodiode and a thin film transistor are arranged like a matrix,   wherein the thin film transistor comprises:   a plurality of gate wiring lines each having a gate electrode;   a semiconductor layer provided for the gate electrode via a gate insulating film; and   a source electrode and a drain electrode connected to the semiconductor layer,   wherein the TFT array substrate comprises:   a passivation film deposited on the thin film transistor, the source electrode and the drain electrode;   a contact hole opened through the passivation film; and   a photodiode connected via the contact hole to the drain electrode, and   wherein the photodiode is arranged inside an opening edge of the contact hole and inside a pattern for the drain electrode, and   wherein a lower layer of the photodiode is substantially flat.   
   
   
       2 . The photosensor according to  claim 1 , further comprising:
 a lower electrode formed so as to be connected to the drain electrode via the contact hole,   wherein the photodiode is arranged so as to be connected via the lower electrode to the drain electrode.   
   
   
       3 . The photosensor according to  claim 2 ,
 wherein the lower electrode is formed to cover the opening edge of the contact hole.   
   
   
       4 . The photosensor according to  claim 2 ,
 wherein the drain electrode includes a connection portion that is located between an area on the semiconductor layer and an area where the photodiode is formed and that connects those two areas, and   wherein an overlap distance of the connection portion where the lower electrode covers the contact hole is greater than an overlap distance of a portion, other than the connection portion, where the lower electrode covers the contact hole.   
   
   
       5 . The photosensor according to  claim 2 ,
 wherein the drain electrode includes a connection portion that is located between an area on a semiconductor layer and an area where the photodiode is formed and that connects those two areas; and   wherein a portion other than the connection portion includes a portion where the lower electrode is positioned inside the opening edge of the contact hole.   
   
   
       6 . The photosensor according to  claim 1 ,
 wherein a step difference is not present in an area where the photodiode is formed.   
   
   
       7 . The photosensor according to  claim 1 ,
 wherein metal used to form the gate electrode contains metal that employs aluminum or copper as the primary element.   
   
   
       8 . The photosensor according to  claim 7 ,
 wherein the metal that employs aluminum as the primary element is either AlNiNd, AlNiSi or AlNiMg.   
   
   
       9 . The photosensor according to  claim 1 ,
 wherein a scintillator is formed above the passivation film, and   wherein at least a digital board on which a low noise amplifier and an A/D converter are mounted, a driver board that drives the thin film transistor and a reading board that reads an electric charge are connected to the photosensor.   
   
   
       10 . The photosensor according to  claim 9 ,
 wherein the scintillator converts X rays into visible light to provide a function for displaying an X ray image.   
   
   
       11 . A photosensor comprising:
 a TFT array substrate of active matrix type, on which a photodiode and a thin film transistor are arranged like a matrix,   wherein the thin film transistor includes   a plurality of gate wiring lines each having a gate electrode,   a semiconductor layer provided for the gate electrode via a gate insulating film, and   a source electrode and a drain electrode connected to the semiconductor layer,   wherein the TFT array substrate includes   a passivation film deposited on the thin film transistor, the source electrode and the drain electrode,   a contact hole opened through the passivation film,   a lower electrode formed so as to be connected via the contact hole to the drain electrode, and   a photodiode formed so as to be connected via the lower electrode to the drain electrode, and   wherein the contact hole is formed at a position different from that of the photodiode.   
   
   
       12 . The photosensor according to  claim 11 ,
 wherein metal used to form the gate electrode contains metal that employs aluminum or copper as the primary element.   
   
   
       13 . The photosensor according to  claim 12 ,
 wherein the metal that employs aluminum as the primary element is either AlNiNd, AlNiSi or AlNiMg.   
   
   
       14 . The photosensor according to  claim 11 ,
 wherein a scintillator is formed above the passivation film, and   wherein at least a digital board on which a low noise amplifier and an A/D converter are mounted, a driver board that drives the thin film transistor and a reading board that reads an electric charge are connected to the photosensor.   
   
   
       15 . The photosensor according to  claim 14 ,
 wherein the scintillator converts X rays into visible light to provide a function for displaying an X ray image.