Matrix array devices with flexible substrates

• US 20020139981A1
• Filed: 02/25/2002
• Published: 10/03/2002
• Est. Priority Date: 04/03/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Young, Nigel D.
• Granted Patent: US 6,974,971 B2
• Time in Patent Office: Days
• US Class Current: 257/72
• CPC Class Codes: G02F 1/133305 Flexible substrates, e.g. plastics, organic film
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H01L 29/78603 characterised by the insulating substrate or support H01L29/78657 takes precedence

Abstract

A matrix array device, for example, an active matrix display device, image sensor, or the like, comprises a matrix circuit (12, 14, 16, 18) carried on a flexible substrate (20) which circuit includes an array of semiconductor devices (12), such as TFTs, occupying discrete areas. Selected regions of the substrate (20) away from the semiconductor devices (12) are formed as areas of weakness to encourage flexing of the substrate to occur preferentially at those regions upon bending of the device and so reduce the risk of damage to the semiconductor devices. The regions, for example, may comprise lines of weakness (50, 52) extending between the semiconductor devices and may be formed by localised thinning of the substrate or by treating the substrate material to modify its stiffness at predetermined areas.

Claims

1. A flexible matrix array device comprising a thin film matrix circuit carried on the surface of a flexible substrate which matrix circuit includes semiconductor devices arranged in a regular array and occupying respective, discrete, areas of the substrate, wherein selected regions of the substrate away from the areas occupied by the semiconductor devices comprise areas of weakness at which flexing of the substrate occurs more readily.

3. A device according to claim 1 or claim 2, wherein the areas of weakness comprise locally thinner regions of the substrate.

4. A device according to claim 3, wherein the locally thinner regions are formed by selective etching of the substrate.

5. A device according to claim 3, wherein the substrate comprises a laminated structure with at least two layers and in which one layer is patterned to form the locally thinner regions.

6. A device according to claim 1 or claim 2, wherein the areas of weakness comprise areas of the substrate at which the material of the substrate is rendered less stiff compared with the areas of the substrate occupied by the semiconductor devices.

7. A device according to any one of claims 1 to 6, wherein the substrate comprises polymer material.

8. A device according to any one of claims 1 to 7, wherein the areas of weakness extend as lines of weakness between the areas of the substrate carrying the semiconductor devices.

9. A device according to claim 8, wherein the semiconductor devices are arranged in an array of rows and columns and wherein the areas of weakness comprise lines of weakness extending across the array between rows and/or columns of semiconductor devices.

10. A device according to any one of claims 1 to 7, wherein the discrete areas of the substrate carrying the semiconductor devices are thicker than the remaining areas of substrate.

11. A device according to any one of the preceding claims, wherein the semiconductor devices each comprise a semiconductor film formed into an island.

12. A device according to any one of the preceding claims, wherein the semiconductor devices comprises thin film transistors.

13. A device according to any one of the preceding claims, wherein the device comprises an active matrix display devices having an array of display pixels and in which each semiconductor device is connected to a respective pixel electrode carried on the substrate.

14. A device according to claim 13, wherein the device comprises an active matrix liquid crystal display device which includes a further flexible substrate mounted to the substrate carrying the matrix circuit with liquid crystal material disposed between the substrates.

15. A device according to claim 14, wherein the further substrate has lines of weakness formed therein.

2. A curved matrix array device comprising a thin film matrix circuit carried on the surface of a substrate which matrix circuit includes semiconductor devices arranged in a regular array and occupying respective, discrete, areas of the substrate, wherein the substrate comprises areas of weakness at selected regions away from the semiconductor devices and the curvature of the device is accommodated substantially by deformation at the substrate at those regions.