Metal-induced crystallization of amorphous silicon in thin film transistors

1. A method of forming a polycrystalline silicon film comprising the steps:

depositing a first layer of amorphous silicon thin film on a substrate;

forming a second layer of thin film on the first layer of amorphous silicon thin film;

patterning the second layer of thin film so that the first layer of amorphous silicon thin film is exposed at selected locations to expose major and minor areas of the first layer, and wherein the second layer is removed when the second layer is organic;

depositing a thin layer of a nickel containing compound on the exposed selected locations on the first amorphous silicon thin film;

removing the second layer of thin film;

forming a native silicon oxide layer on exposed locations of the first layer of amorphous silicon thin film; and

annealing the resulting composite layer of thin film at a sufficient temperature to convert the first layer of amorphous silicon thin film into polycrystalline silicon.

2. A method according to claim 1 , additionally comprising forming a native silicon oxide layer on the exposed locations on the first layer of amorphous silicon thin film.

3. A method according to with claim 1 , wherein the substrate is glass.

4. A method according to claim 1 , wherein the first layer is formed by PECVD, LPCVD ora sputtering process.

5. A method according to with claim 4 , wherein the first layer has a thickness that ranges from about 10 nm to about 300 nm.

6. A method according to with claim 1 , wherein the second layer is a photoresist or silicon oxide.

7. A method according to with claim 6 , wherein the second layer of silicon oxide has a thickness of about 2 nm to about 10 nm.

8. A method according to claim 1 wherein the native silicon oxide layer thickness has a range from about 0 to about 4 nm.

9. A method according to claim 8 , wherein patterning the second layer of thin film is performed by photolithography.

10. A method according to claim 1 , wherein the pattern in the second layer is a series of circular holes with diameters ranging from about 2 to about 30 microns arranged in a square lattice.

11. A method according to claim 1 , wherein the pattern of the second layer is a series of circular holes with diameters ranging from about 2 to about 30 microns arranged in a hexagonal lattice.

12. A method according to claim 1 , wherein the pattern of the second layer is a series of long parallel strips having widths ranging from about 0.5 to about 10 microns, and the distance between the strips is about 10 to about 90 microns.

13. A method according to claim 1 , wherein the pattern of the major areas of the second layer Is a series of circular holes having diameters ranging from about 2 to about 30 microns arranged in a square lattice.

14. A method according to claim 1 , wherein the pattern of the major areas of the second layer is a series of circular holes with diameters ranging from about 2 to about 30 microns arranged in a hexagonal lattice.

15. A method according to claim 1 , wherein the pattern of the major areas of the second layer is a series of long parallel strips with widths ranging from 0.5 to 10 microns, and wherein the distance between the strips is about 10 to about 90 microns.

16. A method according to claim 1 , wherein the pattern of the minor areas of the second layer is a series of circular holes with a diameter ranging from about 0 to about 8 microns, arranged in a square lattice, and wherein the holes have spacing of about 2 to about 10 microns between the major areas.

17. A method according to claim 1 , wherein the pattern of the minor areas of the second layer is a series of circular holes having diameters ranging from about 0 to about 8 microns arranged In a hexagonal lattice, and wherein the holes have spacing of about 2 to about 10 microns between the major areas.

18. A method according to claim 1 , wherein depositing a nickel containing compound includes immersing the first amorphous silicon thin film layer into a solution containing the nickel containing compound.

19. A method according to claim 1 , wherein depositing the nickel containing compound is performed by sputtering or evaporation coating of nickel in a vacuum.

20. A method according to claim 1 , wherein depositing the nickel containing compound is performed by spin coating a nickel containing compound in air.

21. A method according to claim 1 , wherein depositing the nickel containing compound is performed by ion implantation in a vacuum.

22. A method according to claim 1 , wherein annealing is carried out in a nitrogen atmosphere.

23. A method according to claim 1 , wherein annealing is carried out at a temperature between about 450° C. to about 650° C.

24. A thin film transistor device comprising one or more polycrystalline thin films made in according to the method of claim 1 .

25. A method of forming a polycrystalline silicon film comprising:

depositing a first layer of amorphous silicon thin film on a substrate;

forming of a second layer of thin silicon oxide film on the layer;

patterning the second layer of thin silicon oxide film to expose selected major and minor areas of the first layer;

forming a thin native silicon oxide layer on the exposed major and minor areas of the layer;

depositing a thin layer of a nickel containing compound on the second layer of silicon oxide and the thin layer of native silicon oxide to form a resulting composite layer; and

annealing the resulting composite layer at a sufficient temperature to convert the first layer into polycrystalline silicon.