Active matrix of thin-film transistors (tft) for an optical sensors or display screen

• US 20050173703A1
• Filed: 06/28/2002
• Published: 08/11/2005
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson (Government of France), Thomson Licensing (Vantiva SA)
• Inventors: Lebrun, Hugues
• Granted Patent: US 7,199,396 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: H01L 27/0207 Geometrical layout of the components, e.g. computer aided design; custom LSI, semi-custom LSI, standard cell technique
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

The invention relates to an active matrix of thin-film transistors or TFTs for an optical sensor, comprising a matrix of transistors formed on a substrate comprising a gate, a drain and a source, a set of rows and a set of columns that are connected to the gates and to an electrode of the transistor, respectively, pixel electrodes and, according to the invention, a set of capacitive electrodes lying at the same level as the electrodes of the transistors so as to form, with the pixel electrodes, storage capacitors.

Claims

1. An active matrix of thin-film transistors or TFTs for an optical sensor or display screen, comprising:

a substrate;

a matrix of TFT transistors formed on this substrate, each transistor comprising a gate (4), a first electrode or drain (8) and a second electrode or source (9);

a set of row electrodes placed on the substrate for controlling the TFT transistors via their gates;

a conducting level in a defined pattern forming a matrix of pixel electrodes being connected to one of the electrodes of the transistors;

a set of columns for transferring charges through the transistors between the pixel electrodes and drive electronics, the columns being connected to the other electrode of the transistors; and

an insulating layer between the pixel electrodes and the columns, this insulating layer being open locally to each pixel in order to bring the pixel electrode into contact with the other electrode of the transistor;

a set of capacitive electrodes lying at the same level as the electrodes of the transistors so as to form, with the pixel electrodes, storage capacitors.

2. The matrix as claimed in claim 1, wherein the capacitive electrodes are produced in the same material as the source and drain electrodes of the transistors.

3. The matrix as claimed in claim 1, wherein the capacitive electrodes are connected so as to form storage lines parallel to the columns.

4. The matrix as claimed in claim 3, wherein the set of storage lines is connected to the same potential.

5. The matrix as claimed in claim 3, including connections forming a bridge for connecting the storage lines so as to produce a ground plane.

6. The matrix as claimed in claim 1, comprising additional storage lines lying at the same level as the gates of the transistors and parallel to the columns, these additional storage lines forming, with the capacitive electrodes, storage capacitors.

7. The matrix as claimed in claim 6, wherein the additional storage lines are produced in the same material as the gates of the transistors.

8. The matrix as claimed in claim 1, including a photosensitive semiconductor layer in contact with the pixel electrodes in order to convert the electromagnetic radiation into electrical charges picked up by the electrodes.

9. An optical sensor, in particular for X-rays, comprising an active matrix as claimed in claim 1.

12. An optical sensor, in particular for X-rays, comprising an active matrix as claimed in claim 8.

13. The matrix as claimed in claim 1, comprising a layer of liquid crystal, with a back electrode and with a transparent substrate.

14. A display screen of the reflective or transflective type, comprising an active matrix as claimed in claim 1.

10. (canceled)

11. (canceled)

15. A display screen of the reflective or transflective type, comprising comprises an active matrix as claimed in claim 11.