Multi-layer address lines for amorphous silicon liquid crystal display devices

• US 5,153,754 A
• Filed: 11/29/1989
• Issued: 10/06/1992
• Est. Priority Date: 06/30/1989
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Whetten, Nathan R.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/442,864
• Time in Patent Office: 1,042 Days
• Field of Search: 350/336, 350/334, 350/333, 350/339 R, 357/23.7, 357/4, 357/2, 357/67 S, 357/71 S, 357/71 T
• US Class Current: 349/147
• CPC Class Codes: C23F 1/26 for etching refractory metals
• CPC Class Codes: G02F 1/13629 Multilayer wirings
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT

Abstract

Each scan line of a liquid crystal display (LCD) includes: a first layer of titanium disposed on the LCD substrate surface to promote adhesion of the scan line to the substratae surface; a layer of molybdenum or aluminum disposed on the first titanium layer to provide a low resistance address line; and a second layer of titanium disposed on the molybdenum layer to promote adhesion of a subsequently deposited layer of passivation material, semiconductor material or the like over the scan line. The multi-layered scan line side walls may be etched to promote step coverage of subsequently deposited layers of material. The data lines may also have a multi-layer conductor structure similar to the scan lines.

Claims

1. An electrically conductive address line for fabrication upon a relatively large insulative substrate surface, comprising:

a first layer of an electrically conductive, laser-weldable material disposed on said insulative substrate surface and selected to adhere thereto; and

a second layer of an electrically conductive, low bulk resistivity material directly disposed upon said first layer to form a multi-layer conductive line;

said second layer of conductive material being selected from the group consisting of molybdenum and aluminum;

said first and second layers being disposed between and electrically coupled to selected ones of a plurality of active semiconductor devices positioned on said insulative substrate surface in an array having an area greater than about four square inches.

2. The conductive line of claim 1, wherein said first layer conductive material is titanium.

3. The conductive line of claim 1, wherein said multi-layer line has side edges which are tapered to promote step coverage of subsequent layers of material deposited upon said conductive line.

4. The device of claim 1 wherein the width of said first and second conductive layers at the interface between said layers is substantially the same.

5. An electrically conductive address line for fabrication upon a relatively large insulative substrate surface, comprising;

a first layer of an electrically conductive, laser-weldable material disposed on said insulative substrate surface and selected to adhere thereto;

a second layer of an electrically conductive, low bulk resistivity material directly disposed upon said first layer to form a multi-layer conductive line; and

a third layer of an electrically conductive, laser weldable material selected to adhere to a non-metallic overlying surface, said third layer being directly disposed upon said second layer to form a multi-layer line;

said first, second, and third layers being disposed between and electrically coupled to selected ones of a plurality of active semiconductor devices positioned on said insulative substrate surface in an array having an area greater than about four square inches.

6. The conductive line of claim 5, wherein said first conductive layer material and said third conductive layer material are titanium.

7. The conductive line of claim 5, wherein said second conductive layer material is selected from the group consisting of molybdenum and aluminum.

8. The conductive address line of claim 5, wherein said first and third conductive layers are between about 400 and about 1000 angstroms thick.

9. The conductive address line of claim 5, wherein said second conductive layer is about 1000 angstroms thick.

10. The conductive line of claim 5, wherein said multi-layer line has side edges which are tapered to promote step coverage of subsequent layers of material deposited upon said conductive line.

11. A liquid crystal display device, comprising:

a multiplicity of pixels arranged substantially in rows and columns, said pixels forming an array having an area greater than about four square inches;

a plurality of electrically conductive scan lines including at least one scan line for transmitting electrical signals to each row of pixels; and

a plurality of electrically conductive data lines including at least one data line for transmitting electrical signals to each column of pixels;

each of said scan lines insulatively crossing each of said data lines at a different crossover location and comprising;

(a) a first layer of an electrically conductive, laser weldable material disposed on, and adhering to, a surface of a substrate of the liquid crystal display device;

(b) a second layer of an electrically conductive, low bulk resistivity material directly disposed upon said first layer;

respective ones of said scan lines being disposed between and electrically coupled to said pixels arranged in respective ones of said rows.

12. The liquid crystal display device of claim 11, further comprising a third layer of an electrically conductive, laser-weldable material selected to adhere to a non-metallic overlying surface, said third layer being directly disposed upon said second layer to form a multi-layer scan line.

13. The liquid crystal display device of claim 12, wherein said first conductive layer material and said third conductive layer material are titanium.

14. The liquid crystal display device of claim 12, wherein said first and third conductive layers are between about 400 and about 1000 angstroms thick.

15. The liquid crystal display device of claim 11, wherein said second conductive material layer is selected from the group consisting of aluminum and molybdenum.

16. The liquid crystal display device of claim 11, wherein said multi-layer scan line has side edges which are tapered to a degree selected to promote step coverage of subsequent layers of materials deposited upon said scan line.

17. The liquid crystal display device of claim 11, wherein said second conductive layer is about 1000 angstroms thick.

18. The liquid crystal display device of claim 11, wherein said data line comprises a plurality of layers of electrically conductive material.

19. The liquid crystal display device of claim 11, wherein said data line comprises:

a first layer of titanium disposed upon an underlying substrate; and

a second layer, selected from the group consisting of molybdenum and aluminum, disposed upon said first layer.

20. The liquid crystal display device of claim 19, wherein said data line further comprises a third layer of titanium disposed over said second layer.

21. The liquid crystal display device of claim 11, further comprising switching means associated with each of said multiplicity of pixels, said switching means being capable of transferring electrical signals to said pixel from one selected combination of said plurality of scan lines and said plurality of data lines for conversion to a visual signal, said switching means comprising at least one electrode having multiple layer of conductive material and being connected to at least one of said pixels and to said selected combination of conductive scan lines and data lines.

22. The device of claim 11 wherein the width of said first and second conductive layers at the interface between said layers is substantially the same.