Atomic layer-deposited LaAlO3 films for gate dielectrics

• US 7,045,430 B2
• Filed: 05/02/2002
• Issued: 05/16/2006
• Est. Priority Date: 05/02/2002
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Ahn, Kie Y., Forbes, Leonard
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): LINDSAY JR, WALTER LEE
• Application Number:
  US10/137,499
• Publication Number:
  US 20030207540A1
• Time in Patent Office: 1,475 Days
• Field of Search: 438/287, 438/643, 438/618, 438/624, 438/642, 438/652, 438/653, 438/3
• US Class Current: 438/287
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• CPC Class Codes: H01L 21/02192 the material containing at least one rare earth metal element, e.g. oxides of lanthanides, scandium or yttrium
• CPC Class Codes: H01L 21/02194 the material containing more than one metal element
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/31616 Deposition of Al2O3
• CPC Class Codes: H01L 21/31683 of metallic layers, e.g. Al deposited on the body, e.g. formation of multi-layer insulating structures
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material

Abstract

A dielectric film containing LaAlO₃ and method of fabricating a dielectric film contained LaAlO₃ produce a reliable gate dielectric having a thinner equivalent oxide thickness than attainable using SiO₂. The LaAlO₃ gate dielectrics formed are thermodynamically stable such that these gate dielectrics will have minimal reactions with a silicon substrate or other structures during processing. A LaAlO₃ gate dielectric is formed by atomic layer deposition employing a lanthanum sequence and an aluminum sequence. A lanthanum sequence uses La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) and ozone. An aluminum sequence uses either trimethylaluminum, Al(CH₃)₃, or DMEAA, an adduct of alane (AlH₃) and dimethylethylamine [N(CH₃)₂(C₂H₅)], with distilled water vapor.

Claims

1. A method of forming a dielectric film comprising:

pulsing a lanthanum containing precursor into a reaction chamber containing a substrate;

pulsing an aluminum containing precursor into the reaction chamber; and

controlling the pulsing of the lanthanum containing precursor and the pulsing of the aluminum containing precursor to form by atomic layer deposition a dielectric layer containing LaAlO₃ with a predetermined dielectric constant.

2. The method of claim 1, wherein pulsing a lanthanum containing precursor into a reaction chamber is followed by pulsing a first oxygen containing precursor into the reaction chamber.

3. The method of claim 1, wherein pulsing an aluminum containing precursor into the reaction chamber is followed by pulsing a second oxygen containing precursor into the reaction chamber.

4. The method of claim 1, wherein the substrate is maintained at a selected temperature for each pulsing of a precursor, the selected temperature set independently for pulsing each precursor.

5. The method of claim 1, wherein each pulsing of a precursor is followed by purging the reaction chamber with a purging gas.

6. The method of claim 1, further comprising repeating for a number of cycles the pulsing of the lanthanum containing precursor, and the aluminum containing precursor.

7. A method of forming a dielectric film comprising:

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing an aluminum containing source gas into the reaction chamber;

pulsing a second oxygen containing source gas into the reaction chamber; and

controlling the pulsing of the lanthanum containing precursor and the pulsing of the aluminum containing precursor to form by atomic layer deposition a dielectric layer containing LaAlO₃ with a predetermined dielectric constant.

8. The method of claim 7, wherein the first oxygen containing source gas includes ozone.

9. The method of claim 7, wherein the second oxygen containing source gas includes distilled water vapor.

10. The method of claim 7, wherein the second oxygen containing source gas includes oxygen.

11. The method of claim 7, wherein a pulsing period of time, a number of times the source is pulsed into the substrate, and a substrate temperature are independently controlled for each source gas.

12. The method of claim 11, wherein the pulsing period of time, the number of times the source is pulsed into the substrate, and the substrate temperature are controlled for each source gas to form a dielectric film containing LaAlO₃, the dielectric film having a dielectric constant in the range from about 9 to about 30.

13. The method of claim 7, further comprising repeating for a number of cycles the pulsing of the lanthanum containing source gas, the first oxygen containing source gas, the aluminum containing source gas, and the second oxygen containing source gas.

14. The method of claim 13, wherein repeating for a number of cycles the pulsing of the lanthanum containing source gas, the first oxygen containing source gas, the aluminum containing source gas, and the second oxygen containing source gas is followed by annealing at a temperature ranging from about 800°

C. to about 900°

C.

15. A method of forming a dielectric film comprising:

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing an aluminum containing source gas into the reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition.

18. The method of claim 15, wherein a pulsing period of time, a number of times the source is pulsed into the substrate, and a substrate temperature are independently controlled for each source gas.

19. The method of claim 18, wherein the pulsing period of time, the number of times the source is pulsed into the substrate, and the substrate temperature are controlled for each source gas to form a dielectric film containing LaAlO₃, the dielectric film having a dielectric constant in the range from about 9 to about 30.

16. The method of claim 16, wherein pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber is perfonned with the substrate maintained at a temperature ranging from about 180 °

C. to about 425 °

C.

17. The method of claim 16, wherein pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber is performed at a pressure ranging from about 2 mbar to about 3 mbar.

20. A method of forming a dielectric film comprising:

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing a trimethylaluminum source gas into the reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition.

21. The method of claim 20, wherein pulsing the trimethylaluminum source gas into the reaction chamber is performed with the substrate maintained at a temperature ranging from about 350°

C. to about 370°

C. with the reaction chamber having chamber walls maintained at about 150°

C.

22. The method of claim 21, wherein pulsing a trimethylaluminum source gas into the reaction chamber is performed at a pressure of about 230 mTorr.

23. The method of claim 20, wherein a pulsing period of time, a number of times the source is pulsed into the substrate, and a substrate temperature are independently controlled for each source gas.

24. The method of claim 23, wherein the pulsing period of time, the number of times the source is pulsed into the substrate, and the substrate temperature are controlled for each source gas to form a dielectric film containing LaAlO₃, the dielectric film having a dielectric constant in the range from about 9 to about 30.

25. A method of forming a dielectric film comprising:

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing a DMEAA source gas into the reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition.

26. The method of claim 25, wherein pulsing a DMEAA source gas into the reaction chamber is performed with the substrate maintained at a temperature ranging from about 100 °

C. to about 125°

C.

27. The method of claim 26, wherein pulsing a DMEAA source gas into the reaction chamber is performed at a pressure of about 30 mTorr.

28. The method of claim 25, wherein a pulsing period of time, a number of times the source is pulsed into the substrate, and a substrate temperature are independently controlled for each source gas.

30. A method of forming a dielectric film comprising:

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing a trimethylaluminum source gas into the reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition.

29. The method of claim 31, wherein the pulsing period of time, the number of times the source is pulsed into the substrate, and the substrate temperature are controlled for each source gas to form a dielectric film containing LaAlO₃, the dielectric film having a dielectric constant in the range from about 9 to about 30.

31. The method of claim 30, wherein pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber is followed by purging the reaction chamber with nitrogen.

32. The method of claim 31, wherein pulsing a trimethylaluminum source gas into the reaction chamber is followed by purging the reaction chamber with argon.

33. A method of forming a dielectric film comprising:

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing a DMEAA source gas into the reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition.

34. The method of claim 33, wherein pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber is followed by purging the reaction chamber with nitrogen.

35. The method of claim 33, wherein pulsing a DMEAA source gas into the reaction chamber is followed by purging the reaction chamber with hydrogen.

36. A method of forming a transistor, comprising:

forming first and second source/drain regions in a substrate;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing precursor into a reaction chamber containing the substrate;

pulsing a first oxygen containing precursor into the reaction chamber;

pulsing an aluminum containing precursor into the reaction chamber;

pulsing a second oxygen containing precursor into the reaction chamber; and

controlling the pulsing of the lanthanum containing precursor and the pulsing of the aluminum containing precursor to form by atomic layer deposition a dielectric layer containing LaAlO₃ with a predetermined dielectric constant; and

coupling a gate to the film containing LaAlO₃.

37. The method of claim 36, wherein pulsing a lanthanum containing precursor into a reaction chamber includes pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into the reaction chamber.

38. The method of claim 36, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a DMEAA source gas into the reaction chamber.

39. The method of claim 36, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a trimethylaluminum source gas into the reaction chamber.

40. A method of forming a memory array, comprising:

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film containing LaAlO₃ on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing an aluminum containing source gas into a reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber; and

controlling the pulsing of the lanthanum containing source gas and the pulsing of the aluminum containing source gas to form by atomic layer deposition a dielectric layer containing LaAlO₃ with a predetermined dielectric constant; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors; and

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors.

41. The method of claim 40, wherein pulsing a lanthanum containing precursor into a reaction chamber includes pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into the reaction chamber.

42. The method of claim 41, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a DMEAA source gas into the reaction chamber.

43. The method of claim 41, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a trimethylaluminum source gas into the reaction chamber.

44. A method of forming an information handling system, comprising:

providing a processor;

providing a memory array, wherein the memory array is formed by a method comprising;

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film containing LaAlO₃ on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing an aluminum containing source gas into a reaction chamber; and

controlling the pulsing of the lanthanum containing source gas and the pulsing of the aluminum containing source gas to form by atomic layer deposition a dielectric layer containing LaAlO₃ with a predetermined dielectric constant; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors;

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors; and

coupling the processor to the memory array using a system bus.

45. The method of claim 44, wherein pulsing a lanthanum containing precursor into a reaction chamber includes pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into the reaction chamber.

46. The method of claim 44, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a DMEAA source gas into the reaction chamber.

47. The method of claim 44, wherein pulsing an aluminum containing precursor into the reaction chamber includes pulsing a trimethylaluminum source gas into the reaction chamber.

48. A method of forming a transistor, comprising:

forming first and second source/drain regions in a substrate;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) precursor into a reaction chamber containing the substrate;

pulsing a first oxygen containing precursor into the reaction chamber;

pulsing an aluminum containing precursor into the reaction chamber;

pulsing a second oxygen containing precursor into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition; and

coupling a gate to the film containing LaAlO₃.

49. A method of forming a transistor, comprising:

forming first and second source/drain regions in a substrate;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing precursor into a reaction chamber containing the substrate;

pulsing a first oxygen containing precursor into the reaction chamber;

pulsing an aluminum containing precursor into the reaction chamber;

pulsing a second oxygen containing precursor into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition, wherein the aluminum containing precursor is selected from a group consisting of a DMEAA precursor and a trimethylaluminum precursor and

coupling a gate to the film containing LaAlO₃.

50. A method of forming a memory array, comprising:

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing an aluminum containing source gas into a reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors; and

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors.

51. A method of forming a memory array, comprising:

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing a first oxygen containing source gas into the reaction chamber;

pulsing an aluminum containing source gas into a reaction chamber; and

pulsing a second oxygen containing source gas into the reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition, wherein the aluminum containing source gas is selected from a group consisting of a DMEAA source gas and a trimethylaluminum source gas; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors; and

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors.

52. A method of forming an information handling system, comprising:

providing a processor; and

coupling a memory array to the processor using a system bus, wherein forming the memory array includes;

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a La(thd)₃ (thd=2,2,6,6-tetramethyl-3,5-heptanedione) source gas into a reaction chamber containing a substrate;

pulsing an aluminum containing source gas into a reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors; and

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors.

53. A method of forming an information handling system, comprising:

providing a processor; and

coupling a memory array to the processor using a system bus, wherein forming the memory array includes;

forming a number of access transistors, comprising;

forming first and second source/drain regions;

forming a body region between the first and second source/drain regions;

forming a film on the body region between the first and second source/drain regions, comprising;

pulsing a lanthanum containing source gas into a reaction chamber containing a substrate;

pulsing an aluminum containing source gas into a reaction chamber to form a dielectric film containing LaAlO₃ by atomic layer deposition, wherein the aluminum containing source gas is selected from a group consisting of a DMEAA source gas and a trimethylaluminum source gas; and

coupling a gate to the film containing LaAlO₃;

forming a number of word lines coupled to a number of the gates of the number of access transistors;

forming a number of source lines coupled to a number of the first source/drain regions of the number of access transistors; and

forming a number of bit lines coupled to a number of the second source/drain regions of the number of access transistors.