SYSTEM FOR AND METHOD OF MICROWAVE ANNEALING SEMICONDUCTOR MATERIAL

• US 20090184399A1
• Filed: 09/17/2008
• Published: 07/23/2009
• Est. Priority Date: 09/17/2007
• Status: Active Grant

• Current Assignee: DSGI Incorporated
• Original Assignee: DSGI Incorporated
• Inventors: Kowalski, Jeffrey Edward, Kowalski, Jeffrey Michael
• Granted Patent: US 7,928,021 B2
• Time in Patent Office: Days
• US Class Current: 257/618
• CPC Class Codes: H01L 21/324 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/20 - H01L21/288 and H01L21/302 - H01L21/322 take precedence
• CPC Class Codes: H01L 21/67098 Apparatus for thermal treatment
• CPC Class Codes: H01L 21/67115 mainly by radiation

Abstract

A system for and method of processing, i.e., annealing semiconductor materials. By controlling the time, frequency, variance of frequency, microwave power density, wafer boundary conditions, ambient conditions, and temperatures (including ramp rates), it is possible to repair localized damage lattices of the crystalline structure of a semiconductor material that may occur during the ion implantation of impurities into the material, electrically activate the implanted dopant, and substantially minimize further diffusion of the dopant into the silicon. The wafer boundary conditions may be controlled by utilizing susceptor plates (4) or a water chill plate (12). Ambient conditions may be controlled by gas injection (10) within the microwave chamber (3).

Claims

1. A method of annealing treatment of a semiconductor wafer comprising the steps of:

a. introducing the semiconductor wafer within a microwave chamber;

b. supporting at least one semiconductor wafer with a wafer rack in close proximity to at least one susceptor;

c. applying controlled microwave radiation at a frequency to the microwave chamber from at least one source;

d. controlling the frequency within a range of approximately 900 MHz to approximately 150 GHz.

3. A method according to claim 1 in which the microwave radiation is in the frequency range of approximately 900 MHz to approximately 100 GHz.

4. A method according to claim 1 in which the microwave radiation is in the frequency range of approximately 5 GHz to approximately 50 GHz.

5. A method according to claim 1 in which the microwave radiation is in the frequency range of approximately 5 GHz to approximately 10 GHz.

6. A method according to claim 1 wherein the microwave radiation is in the frequency of approximately 5.8 GHz.

7. A method according to claim 1 wherein applying controlled microwave radiation comprises generating microwave radiation from multiple sources having an operable variance of frequency, and the operable variance of the frequencies is approximately 50 MHz.

8. A method according to claim 1 wherein the microwave chamber has dimensions substantially equal to a multiple of the wavelength of the microwave radiation.

9. A method according to claim 1 where multiple magnetrons are used to vary the frequency of the microwave radiation producing a substantially uniform microwave field.

10. A method according to claim 1 where a slightly unstable DC signal is used to vary the frequency of the microwave radiation within 50 MHz.

11. A method according to claim 1, further comprising positioning the susceptor below the semiconductor wafer, and wherein the pitch between the susceptor and the semiconductor wafer is approximately between 1 mm and 30 mm.

12. A method according to claim 1, wherein the susceptor material comprises fused quartz.

13. A method according to claim 1, wherein the susceptor material comprises a select one of silicon, silicon carbide, or other materials with similar properties.

14. A method according to claim 1, further comprising cooling the susceptor and positioning the susceptor in contact with the semiconductor wafer to provide a greater thermal gradient through the thickness of the wafer.

15. A method according to claim 1, further comprising creating a controlled microwave field around the semiconductor wafer by selecting the susceptor material and adjusting the susceptor pitch.

16. A method according to claim 1, further comprising cooling the susceptor with gas or water.

17. A method according to claim 1, wherein applying controlled microwave radiation comprises heating the semiconductor wafer to temperatures approximately between 350 degrees C. and 800 degrees C.

18. A method according to claim 1, further comprising controlling the ambient conditions within the chamber by gas injection into the process tube.

19. A method according to claim 1, wherein the pressure within the process tube is at atmospheric pressure.

20. A method according to claim 1, wherein the pressure within the process tube is a vacuum.

21. A method according to claim 1, further comprising applying controlled microwave radiation a second time and heating the semiconductor wafer to a temperature greater than approximately 800 degrees C.

22. A method according to claim 1, wherein applying controlled microwave radiation comprises applying controlled microwave radiation for approximately between 1 second and 60 minutes.

23. A method according to claim 1, wherein applying microwave radiation is substantially continuous throughout the annealing treatment.

24. A method according to claim 1, further comprising introducing between 1 and 25 semiconductor wafers at a time within the chamber.

25. A method according to claim 1, wherein the semiconductor wafer had been deactivated.

2. A method according to claim 2 wherein the semiconductor wafer has an implant region containing implant dopant ions and the dopant ions have a concentration profile and applying microwave radiation does not substantially change the concentration profile during the annealing treatment.

26. A method of using a susceptor in close proximity to a semiconductor wafer at a relatively low temperature, a relatively low power level microwave energy, and a relatively long exposure time to repair damage to a crystalline structure of the semiconductor wafer that occurs during an ion-implantation of impurities into the water, comprising:

controlling the temperature at approximately below 750 degrees C.;

maintaining the power level at approximately below 10 W/cm2, exposing the wafer for approximately at least 1 second, and controlling the frequency of the microwave radiation from multiple sources within a range of approximately 900 MHz to approximately 150 GHz with an operable variance of frequencies between the multiple sources.

27. A method according to claim 26 in which the microwave radiation is in the frequency range of approximately 900 MHz to approximately 100 GHz.

28. A method according to claim 26 in which the microwave radiation is in the frequency of approximately 5.8 GHz.

29. A method according to claim 26 in which the operable variance of the frequency is approximately 50 MHz.

30. A method according to claim 26 where a frequency coupling is achieved by utilizing a multimode microwave chamber with dimensions substantially equal to a multiple of the wavelength of the microwave radiation.

31. A method according to claim 26 where multiple magnetrons are used to vary the frequency of the microwave radiation.

32. A method according to claim 26 where a slightly unstable DC signal is used to vary the frequency of the microwave radiation within 50 MHz.

33. A system for annealing semiconductor material, the system comprising:

a chamber;

a plurality of sources of microwave energy arranged around the chamber, each source of microwave energy including a magnetron operable to provide microwave energy having a frequency of approximately between 900 MHz and 150 GHz;

a tube located within the chamber, having dimensions substantially equal to a multiple of the wavelength of the microwave radiation, and operable to receive the material;

an elevator operable to raise and lower the material into and out of the tube;

a rack operable to support the material within the tube, and a temperature sensing device operable to monitor the temperature of the material and to control the plurality of microwave energy sources to maintain the temperature of the material at or below a maximum temperature of approximately 800 degrees C.;

the power level of the microwave energy is maintained approximately below 10 W/cm2; and

the exposure time of the material to the microwave energy is at least approximately 1 second.

34. The system as set forth in claim 33, wherein the tube and rack comprise at least in part fused quartz.

35. The system as set forth in claim 33, wherein the temperature sensing device includes an infra-red pyrometer.

36. The system as set forth in claim 33, wherein the temperature sensing device includes a non-contact temperature sensing device.

37. The system as set forth in claim 33, wherein the frequency is approximately between 900 MHz and 100 GHz.

38. The system as set forth in claim 33, wherein the frequency is approximately 5.8 GHz.

39. The system as set forth in claim 33, wherein the operable variance is approximately 50 MHz.

40. The system as set forth in claim 33, further including a susceptor plate operable to facilitate both achieving a uniform microwave field across the material and maintaining the temperature of the material at or below the desired maximum temperature.

41. The system as set forth in claim 40, wherein the susceptor plate includes a recess for closely receiving the semiconductor material such that the susceptor plate closely surrounds and absorbs excess heat from the edges of the semiconductor material.

42. The system as set forth in claim 40, further including a water chill plate located below and in contact with the susceptor plate.

43. The system as set forth in claim 33 where multiple magnetrons are used to vary the frequency of the microwave radiation.

44. The system as set forth in claim 33 where a slightly unstable DC signal is used to vary the frequency of the microwave radiation within 50 MHz.

45. A semiconductor annealing apparatus comprising:

a. an annealing chamber;

b. a semiconductor support operative to support a semiconductor inside the annealing chamber;

c. a susceptor operatively positioned relative to the support to control annealing of the semiconductor, and

d. a radiation generator operative to introduce a first amount of radiation at a frequency within a range of approximately 900 MHz to 150 GHz into the annealing chamber and thereafter introduce a second amount of radiation into the annealing chamber.

46. The annealing apparatus according to claim 45 further comprising a water chill plate adjacent the susceptor.

47. The annealing apparatus according to claim 46 wherein the water chill plate is in contact with the susceptor.

48. The annealing apparatus according to claim 45 further comprising a second susceptor operatively positioned relative to the support to control annealing of the semiconductor.

49. The annealing apparatus according to claim 48 wherein the susceptor and second susceptor are positioned on opposite sides of the semiconductor.

50. The annealing apparatus according to claim 49 wherein the susceptor is positioned below the semiconductor and second susceptor is positioned above the semiconductor.

51. The annealing apparatus according to claim 45 wherein the susceptor comprises a ring shape.

52. The annealing apparatus according to claim 45 further comprising a temperature sensing device operative to sense the temperature of the semiconductor.

53. The annealing apparatus according to claim 45 wherein the radiation generator is operative during the introduction of the first amount of radiation to heat the semiconductor to a low annealing temperature and during introduction of the second amount of radiation to heat the semiconductor to a high annealing temperature.

54. The annealing apparatus according to claim 53 wherein the low annealing temperature comprises less than approximately 800 degrees C. and the high annealing temperature comprises greater than approximately 800 degrees C.

55. The annealing apparatus according to claim 45 wherein the low annealing temperature comprises a range of approximately 350 degrees C. to approximately 800 degrees C.

56. The annealing apparatus according to claim 45 wherein the radiation generator comprises a microwave generator.

57. The annealing apparatus according to claim 45, wherein the frequency is approximately between 900 MHz and 100 GHz.

58. The annealing apparatus according to claim 45, wherein the frequency is approximately 5.8 GHz.

59. The annealing apparatus according to claim 45, further comprising multiple radiation generators having an operable variance of approximately 50 MHz between frequencies of the generators.

60. The annealing apparatus according to claim 45, wherein the microwave chamber has dimensions substantially equal to a multiple of the wavelength of the microwave radiation.

61. The annealing apparatus according to claim 45, wherein multiple magnetrons are used to vary the frequency of the microwave radiation.

62. The annealing apparatus according to claim 45, wherein a slightly unstable DC signal is used to vary the frequency of the microwave radiation.

63. A semiconductor wafer comprising:

a semiconductor material;

a metallic operational structure, and

wherein the semiconductor wafer was annealed at approximately below 500 degrees C. at a frequency within the range of approximately 900 MHz to approximately 150 GHz.

64. A method for treatment of a semiconductor utilizing microwave radiation, the method comprising:

introducing the semiconductor into a microwave chamber;

positioning the semiconductor relative to a susceptor to control treatment of the semiconductor;

heating the semiconductor a first time to a low treatment temperature of approximately between 100 degrees C. and 800 degrees C.;

heating the semiconductor a second time to a high treatment temperature above approximately 800 degrees C.; and

controlling the frequency of the microwave radiation within a range of approximately 900 MHz to approximately 150 GHz.

65. A method according to claim 64 in which the microwave radiation is in the frequency range of approximately 900 MHz to approximately 100 GHz.

66. A method according to claim 64 in which the microwave radiation is in the frequency of approximately 5.8 GHz.

67. A method according to claim 64 in which the semiconductor was annealed with multiple radiation generators having an operable variance between frequencies of approximately 50 MHz.

68. A method according to claim 64 where a frequency coupling is achieved by utilizing a microwave chamber with dimensions substantially equal to a multiple of the wavelength of the microwave radiation.

69. A method according to claim 64 where multiple magnetrons are used to vary the frequency of the microwave radiation.

70. A method according to claim 64 where a slightly unstable DC signal is used to vary the frequency of the microwave radiation.

71. The method according to claim 64 wherein heating the semiconductor comprises exposing the semiconductor to radiation.

72. The method according to claim 64 wherein heating the semiconductor comprises exposing the semiconductor to microwave radiation.

73. The method according to claim 64 wherein heating the semiconductor the first time is maintained for approximately between 100 seconds and 300 seconds.

74. The method according to claim 64 wherein the low treatment temperature is between approximately 350 and 500 degrees C.