Advanced process control of the manufacture of an oxide-nitride-oxide stack of a memory device, and system for accomplishing same

• US 6,953,697 B1
• Filed: 10/22/2002
• Issued: 10/11/2005
• Est. Priority Date: 10/22/2002
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Chong, Robert J., Green, Eric O., Cusson, Brian K., Castle, Howard E.
• Primary Examiner(s): Booth, Richard A.
• Application Number:
  US10/277,357
• Time in Patent Office: 1,085 Days
• Field of Search: 438257-267, 438/954, 438/7, 438/10
• US Class Current: 438/7
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: Y10S 438/954 Making oxide-nitride-oxide device

Abstract

The present invention is generally directed to an advanced process control of the manufacture of memory devices, and a system for accomplishing same. In one illustrative embodiment, the method comprises performing at least one process operation to form at least one layer of an oxide-nitride-oxide stack of a memory cell, the stack being comprised of a first layer of oxide positioned above a first layer of polysilicon, a layer of silicon nitride positioned above the first layer of oxide, and a second layer of oxide positioned above the layer of silicon nitride. The method further comprises measuring at least one characteristic of at least one of the first layer of polysilicon, the first oxide layer, the layer of silicon nitride, and the second layer of oxide and adjusting at least one parameter of at least one process operation used to form at least one of the first oxide layer, the layer of silicon nitride and the second oxide layer if the measured at least one characteristic is not within acceptable limits.

Claims

1. A method, comprising:

performing at least one process operation to form at least one layer of an oxide-nitride-oxide stack of a memory cell, said stack being comprised of a first layer of oxide positioned above a first layer of polysilicon, a layer of silicon nitride positioned above said first layer of oxide, and a second layer of oxide positioned above said layer of silicon nitride;

measuring a refractive index of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide; and

adjusting at least one parameter of at least one process operation used to form at least one of said first oxide layer, said layer of silicon nitride and said second oxide layer if said measured refractive index is not within acceptable limits.

2. The method of claim 1, wherein performing at least one process operation comprises performing a deposition process to form said first layer of oxide.

3. The method of claim 1, wherein performing at least one process operation comprises performing a deposition process to form said layer of silicon nitride.

4. The method of claim 1, wherein performing at least one process operation comprises performing a thermal growth process to form said second layer of oxide.

5. The method of claim 1, further comprising measuring a capacitance of at least one of said first oxide layer, said layer of silicon nitride and said second layer of oxide.

6. The method of claim 1, wherein measuring a refractive index of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide comprises measuring a refractive index of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

7. The method of claim 1, wherein measuring a refractive index of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide comprises measuring a refractive index of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

8. The method of claim 1, further comprising measuring at least one of a sheet resistance and a dopant concentration level of said first layer of polysilicon.

9. The method of claim 1, further comprising performing said at least one process with said at least one adjusted parameter to form at least one of a first oxide layer, a layer of silicon nitride, and a second layer of oxide on a subsequently process substrate.

20. The method of claim 1, further comprising measuring an extinction coefficient of at least one of said first oxide layer, said layer of silicon nitride and said second layer of oxide.

21. The method of claim 1, further comprising measuring a flat band voltage of at least one of said first oxide layer, said layer of silicon nitride and said second layer of oxide.

22. The method of claim 1, further comprising measuring an extinction coefficient of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

23. The method of claim 1, further comprising measuring a flat band voltage of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

24. The method of claim 1, further comprising measuring an extinction coefficient of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

25. The method of claim 1, further comprising measuring a flat band voltage of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

10. A method, comprising:

performing at least one process operation to form a first oxide layer of an oxide-nitride-oxide stack of a memory cell;

measuring a refractive index of said first oxide layer; and

adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured refractive index of said first oxide layer.

11. The method of claim 10, further comprising measuring a capacitance of said first oxide layer.

12. The method of claim 10, wherein adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured refractive index of said first oxide layer comprises adjusting at least one of a temperature, a pressure and a duration of a deposition process used to form said layer of silicon nitride above said first oxide layer.

13. The method of claim 10, wherein adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured refractive index of said first oxide layer comprises adjusting at least one of a temperature, a duration of a thermal growth process used to form said second layer of silicon oxide above said layer of silicon nitride.

14. A method, comprising:

performing at least one process operation to form a layer of silicon nitride above a first layer of oxide of an oxide-nitride-oxide stack of a memory cell;

measuring a refractive index of said layer of silicon nitride; and

adjusting at least one parameter of a process operation to be performed to form a second layer of oxide above said layer of silicon nitride based upon said measured refractive index of said layer of silicon nitride.

15. The method of claim 14, further comprising measuring a capacitance of said layer of silicon nitride.

16. The method of claim 14, wherein adjusting at least one parameter of a process operation to be performed to form said second layer of oxide above said layer of silicon nitride based upon said measured refractive index of said layer of silicon nitride comprises adjusting at least one of a temperature, a pressure and a duration of a thermal growth process used to form said second layer of oxide above said layer of silicon nitride.

17. A method, comprising:

performing at least one process operation to form a first oxide layer, a layer of silicon nitride and a second oxide layer of an oxide-nitride-oxide stack of a memory cell;

measuring a refractive index of said oxide-nitride-oxide stack; and

adjusting at least one parameter of a process operation to be performed to form at least one layer of an oxide-nitride-oxide stack above a subsequently processed substrate based upon said measured refractive index of said measured oxide-nitride-oxide stack.

18. The method of claim 17, further comprising measuring a capacitance of said oxide-nitride-oxide stack.

19. The method of claim 17, wherein adjusting at least one parameter of a process operation to be performed to form at least one layer of an oxide-nitride-oxide stack to be formed above a subsequently processed substrate comprises adjusting at least one of a temperature, a pressure and a duration of a deposition process or a thermal growth process.

26. A method, comprising:

performing at least one process operation to form at least one layer of an oxide-nitride-oxide stack of a memory cell, said stack being comprised of a first layer of oxide positioned above a first layer of polysilicon, a layer of silicon nitride positioned above said first layer of oxide, and a second layer of oxide positioned above said layer of silicon nitride;

measuring a capacitance of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide; and

adjusting at least one parameter of at least one process operation used to form at least one of said first oxide layer, said layer of silicon nitride and said second oxide layer if said measured capacitance is not within acceptable limits.

27. The method of claim 26, wherein performing at least one process operation comprises performing a deposition process to form said first layer of oxide.

28. The method of claim 26, wherein performing at least one process operation comprises performing a deposition process to form said layer of silicon nitride.

29. The method of claim 26, wherein performing at least one process operation comprises performing a thermal growth process to form said second layer of oxide.

30. The method of claim 26, further comprising measuring a refractive index of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide.

31. The method of claim 26, wherein measuring a capacitance of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide comprises measuring a capacitance of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

32. The method of claim 26, wherein measuring a capacitance of at least one of said first layer of polysilicon, said first oxide layer, said layer of silicon nitride, and said second layer of oxide comprises measuring a capacitance of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

33. The method of claim 26, further comprising measuring at least one of a sheet resistance and a dopant concentration level of said first layer of polysilicon.

34. The method of claim 26, further comprising performing said at least one process with said at least one adjusted parameter to form at least one of a first oxide layer, a layer of silicon nitride, and a second layer of oxide on a subsequently process substrate.

45. The method of claim 26, further comprising measuring an extinction coefficient of at least one of said first oxide layer, said layer of silicon nitride and said second layer of oxide.

46. The method of claim 26, further comprising measuring a flat band voltage of at least one of said first oxide layer, said layer of silicon nitride and said second layer of oxide.

47. The method of claim 26, further comprising measuring an extinction coefficient of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

48. The method of claim 26, further comprising measuring a flat band voltage of a combination comprised of at least two of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

49. The method of claim 26, further comprising measuring an extinction coefficient of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

50. The method of claim 26, further comprising measuring a flat band voltage of a combination comprised of said first layer of oxide, said layer of silicon nitride and said second layer of oxide.

35. A method, comprising:

performing at least one process operation to form a first oxide layer of an oxide-nitride-oxide stack of a memory cell;

measuring a capacitance of said first oxide layer; and

adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured capacitance of said first oxide layer.

36. The method of claim 35, further comprising measuring a refractive index of said first oxide layer.

37. The method of claim 35, wherein adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured capacitance of said first oxide layer comprises adjusting at least one of a temperature, a pressure and a duration of a deposition process used to form said layer of silicon nitride above said first oxide layer.

38. The method of claim 35, wherein adjusting at least one parameter of a process operation to be performed to form at least one of a layer of silicon nitride and a second layer of oxide above said first oxide layer based upon said measured capacitance of said first oxide layer comprises adjusting at least one of a temperature, a duration of a thermal growth process used to form said second layer of silicon oxide above said layer of silicon nitride.

39. A method, comprising:

performing at least one process operation to form a layer of silicon nitride above a first layer of oxide of an oxide-nitride-oxide stack of a memory cell;

measuring a capacitance of said layer of silicon nitride; and

adjusting at least one parameter of a process operation to be performed to form a second layer of oxide above said layer of silicon nitride based upon said measured capacitance of said layer of silicon nitride.

40. The method of claim 39, further comprising measuring a refractive index of said layer of silicon nitride.

41. The method of claim 39, wherein adjusting at least one parameter of a process operation to be performed to form said second layer of oxide above said layer of silicon nitride based upon said measured capacitance of said layer of silicon nitride comprises adjusting at least one of a temperature, a pressure and a duration of a thermal growth process used to form said second layer of oxide above said layer of silicon nitride.

42. A method, comprising:

performing at least one process operation to form a first oxide layer, a layer of silicon nitride and a second oxide layer of an oxide-nitride-oxide stack of a memory cell;

measuring a capacitance of said oxide-nitride-oxide stack; and

adjusting at least one parameter of a process operation to be performed to form at least one layer of an oxide-nitride-oxide stack above a subsequently processed substrate based upon said measured capacitance of said measured oxide-nitride-oxide stack.

43. The method of claim 42, further comprising measuring a refractive index of said oxide-nitride-oxide stack.

44. The method of claim 42, wherein adjusting at least one parameter of a process operation to be performed to form at least one layer of an oxide-nitride-oxide stack to be formed above a subsequently processed substrate comprises adjusting at least one of a temperature, a pressure and a duration of a deposition process or a thermal growth process.