Ping, Er-Xuan; Thakur, Randhir;

Formation of conductive rugged silicon

The present invention provides methods of forming in situ doped rugged silicon and semiconductor devices incorporating conductive rugged silicon. In one aspect, the methods involve forming a layer of doped amorphous silicon on a substrate at a substantially constant deposition temperature; and converting the amorphous silicon layer into hemispherical grain silicon by annealing the amorphous silicon layer at substantially the deposition temperature while varying pressure. In another aspect, the methods involve forming a discontinuous first layer of doped silicon on a substrate; forming a second layer of amorphous silicon on the first layer of doped silicon and the substrate not covered by the first layer of doped silicon; and annealing the first and second layers. In yet another aspect, the methods involve forming a discontinuous first layer of silicon on a substrate and forming a second conformal layer of doped amorphous silicon on the first layer of doped silicon.

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What is claimed is:

1. A method of forming hemispherical grain silicon comprising:

forming a layer of doped amorphous silicon on a substrate at a substantially constant deposition temperature within a chamber at a chamber pressure; and

converting the amorphous silicon layer into hemispherical grain silicon by annealing the amorphous silicon layer at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

2. A method of forming hemispherical grain silicon comprising:

forming a layer of doped amorphous silicon on a substrate at a substantially constant deposition temperature of about 565 to about 575.degree. C. within a chamber at a chamber pressure; and

converting the amorphous silicon layer into hemispherical grain silicon by annealing the amorphous silicon layer at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

3. A method according to claim 2 wherein the chamber pressure during annealing is about 20 mTorr to about 20 Torr.

4. A method of forming hemispherical grain silicon comprising:

forming a first layer of in situ doped amorphous silicon on a substrate at a deposition temperature;

forming a second layer of undoped amorphous silicon on the first layer, the second layer being formed at the deposition temperature within a chamber at a chamber pressure; and

converting the first and second layers into hemispherical grain silicon by annealing the first and second layers at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

5. A method of forming hemispherical grain silicon comprising:

forming a first layer of doped amorphous silicon on a substrate at a substantially constant deposition temperature of about 565 to about 575.degree. C.;

forming a second layer of undoped amorphous silicon on the first layer, the second layer being formed at the deposition temperature within a chamber at a chamber pressure; and

converting the first and second layers into hemispherical grain silicon by annealing the first and second layers at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

6. A method according to claim 5 wherein the chamber pressure during annealing is about 20 mTorr to about 20 Torr.

7. A method for manufacturing a semiconductor device comprising:

forming a layer of doped amorphous silicon on a substrate at a substantially constant deposition temperature within a chamber at a chamber pressure;

converting the amorphous silicon layer into hemispherical grain silicon by annealing the amorphous silicon layer at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure, wherein the hemispherical grain silicon forms a first electrode of a capacitor;

providing a layer of dielectric material on the first electrode; and

providing a second electrode of the capacitor on the dielectric material.

8. A method of forming hemispherical grain silicon comprising:

forming a layer of doped substantially amorphous silicon on a substrate located within a chamber at a chamber pressure, wherein the substrate is heated to a deposition temperature during formation of the layer that is in a range of temperatures above which substantially amorphous silicon would typically be deposited and below which substantially polycrystalline silicon would typically be deposited; and

annealing the layer of doped substantially amorphous silicon at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

9. A method according to claim 8, wherein the range of temperatures is from about 560 degrees Celsius to about 590 degrees Celsius.

10. A method according to claim 8 wherein the chamber pressure during annealing is about 20 mTorr to about 20 Torr.

11. A method of forming hemispherical grain silicon comprising:

forming a first layer of doped substantially amorphous silicon on a substrate that is heated to a deposition temperature during formation of the first layer that is in a range of temperatures above which substantially amorphous silicon would typically be deposited and below which substantially polycrystalline silicon would typically be deposited;

forming a second layer of undoped substantially amorphous silicon on the first layer, the second layer being formed at the deposition temperature within a chamber at a chamber pressure; and

annealing the first and second layers at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

12. A method according to claim 11, wherein the range of temperatures is from about 560 degrees Celsius to about 590 degrees Celsius.

13. A method of forming hemispherical grain silicon comprising:

forming a layer of doped substantially amorphous silicon on a substrate located within a chamber at a chamber pressure by providing a growth gas to the chamber at a flow rate of about 50 sccm or greater, wherein the substrate is heated to a deposition temperature during formation of the first layer that is in a range of temperatures above which substantially amorphous silicon would typically be deposited and below which substantially polycrystalline silicon would typically be deposited; and

annealing the layer of doped substantially amorphous silicon at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

14. A method according to claim 13, wherein the flow rate of growth gas is about 100 sccm or greater.

15. A method according to claim 13, wherein the flow rate of growth gas is about 200 sccm or greater.

16. A method according to claim 13, wherein the growth gas comprises disilane.

17. A method according to claim 13, wherein at least a portion of the growth gas comprises a gas that is more reactive than silane.

18. A method according to claim 13, wherein at least a portion of the growth gas comprises a gas selected from the group consisting of disilane, silichloroform, and combinations thereof.

19. A method according to claim 13, wherein the growth gas is selected from the group consisting of disilane, silichloroform, and combinations thereof.

20. A method according to claim 13 wherein the chamber pressure during annealing is about 20 mTorr to about 20 Torr.

21. A method of forming hemispherical grain silicon comprising:

forming a first layer of doped substantially amorphous silicon on a substrate located in a chamber by providing a growth gas to the chamber at a flow rate of about 50 sccm or greater, wherein the substrate is heated to a deposition temperature during formation of the first layer that is in a range of temperatures above which substantially amorphous silicon would typically be deposited and below which substantially polycrystalline silicon would typically be deposited;

forming a second layer of undoped substantially amorphous silicon on the first layer, the second layer being formed at the deposition temperature and a chamber pressure; and

annealing the first and second layers of substantially amorphous silicon at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.

22. A method according to claim 21, wherein the flow rate of growth gas is about 100 sccm or greater.

23. A method according to claim 21, wherein the flow rate of growth gas is about 200 sccm or greater.

24. A method according to claim 21, wherein the growth gas comprises disilane.

25. A method according to claim 21, wherein at least a portion of the growth gas comprises a gas that is more reactive than silane.

26. A method according to claim 21, wherein at least a portion of the growth gas comprises a gas selected from the group consisting of disilane, silichloroform, and combinations thereof.

27. A method according to claim 21, wherein the growth gas is selected from the group consisting of disilane, silichloroform, and combinations thereof.

28. A method according to claim 21 wherein the chamber pressure during annealing is about 20 mTorr to about 20 Torr.

29. A method of forming hemispherical grain silicon comprising:

forming a first layer of doped substantially amorphous silicon on a substrate that is heated to a deposition temperature during formation of the first layer that is in a range of temperatures above which substantially amorphous silicon would typically be deposited and below which substantially polycrystalline silicon would typically be deposited;

forming a second layer of doped substantially amorphous silicon on the first layer, the second layer being formed at the deposition temperature within a chamber at a chamber pressure, wherein the second layer has a dopant concentration less than a dopant concentration of the first layer; and

annealing the first and second layers at substantially the deposition temperature or less at an annealing pressure that is different from the chamber pressure.