Sensor for semiconductor device manufacturing process control

• US 5,293,216 A
• Filed: 12/31/1990
• Issued: 03/08/1994
• Est. Priority Date: 12/31/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Moslehi, Mehrdad M.
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): HANTIS, KAREN
• Application Number:
  US07/638,472
• Time in Patent Office: 1,163 Days
• Field of Search: 356/73, 356/443-448, 356/237, 356/371, 219/121.6, 250/227.29
• US Class Current: 356/600
• CPC Class Codes: G01B 11/0616 of coating
• CPC Class Codes: G01B 11/303 using photoelectric detection means
• CPC Class Codes: G03F 7/70483 Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
• CPC Class Codes: H01L 21/67207 comprising a chamber adapted to a particular process
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/682 Mask-wafer alignment in general G03F7/70, G03F9/70
• 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

Abstract

A fiber-optic sensor device (210) for semiconductor device manufacturing process control measures polycrystalline film thickness as well as surface roughness and spectral emissivity of semiconductor wafer (124). The device (210) comprises a sensor arm (212) and an opto-electronic interface and measurement box (214), for directing coherent laser energy in the direction of semiconductor wafer (124). Opto-electronic interface/measurement unit (214) includes circuitry for measuring the amounts of laser power coherently reflected in the specular direction from the semiconductor wafer (124) surface, scatter reflected from the semiconductor wafer (124) surface, coherently transmitted in the specular direction through the semiconductor wafer (124), and scatter transmitted through the semiconductor wafer (124). The present invention determines the semiconductor wafer (124) surface roughness and spectral emissivity values using the measured optical powers of incident, specular reflected, scatter reflected, specular transmitted, and scatter transmitted beams.

Claims

1. A sensor for semiconductor device manufacturing process control wherein said semiconductor device is on a semiconductor wafer comprising:

a coherent electromagnetic beam energy source;

a fiber optic network associated with said energy source, said fiber optic network including a fiber termination for directing coherent electromagnetic beam energy in the direction of the semiconductor wafer and for receiving coherent electromagnetic beam energy reflected from the semiconductor wafer in a specular direction;

a first receive sensor element connected to said fiber termination for measuring the coherent electromagnetic beam energy reflected in the spectral direction as coherent beam power;

a second receive sensor element for measuring electromagnetic beam energy reflected as scattered beam power from the semiconductor wafer, said second receive sensor element measuring simultaneously with said first receive sensor element;

a lens for focusing said electromagnetic beam energy reflected as scattered beam power to said second receive sensor and disposed between said semiconductor wafer and said fiber termination; and

circuitry of determining semiconductor wafer surface roughness based on the measurements of said beam energy reflected as coherent beam power and reflected as scattered beam power.

2. The apparatus of claim 1, further comprising:

a transmit sensor element for measuring the amount of electromagnetic power coherently transmitted through the semiconductor wafer in the specular direction and the amount of electromagnetic power scatter transmitted through the semiconductor wafer, and wherein said determining circuitry further includes circuitry for including said coherently transmitted power and scatter transmitted power in determining said semiconductor wafer surface roughness.

3. The apparatus of claim 2, wherein said transmit sensor element comprises a specular transmission sensor for receiving said coherently transmitted electromagnetic power and a scatter transmission sensor for detecting said scatter transmitted electromagnetic power, said scatter transmission sensor comprising an imaging lens for focusing said scatter transmitted electromagnetic power to said scatter transmission sensor.

4. The apparatus of claim 3, wherein said specular transmission sensor further comprises an imaging lens for focusing said coherently transmitted electromagnetic power to said specular transmission sensor.

5. The apparatus of claim 1, wherein said sensor operates in a semiconductor wafer processing reactor.

6. The apparatus of claim 1, wherein said coherent laser energy source emits coherent energy in the range of 0.4-15 μ

m.

7. The apparatus of claim 1, wherein said coherent laser energy source emits coherent energy of approximately 1.3 μ

m.

8. The apparatus of claim 1, wherein said coherent laser energy source emits coherent energy of approximately 1.55 μ

m.

9. The apparatus of claim 1 wherein said semiconductor device includes films of selected materials and further comprising circuitry for extracting a film thickness value of said materials based on measurements of said semiconductor wafer surface roughness.

10. The apparatus of claim 9, wherein said films of selected materials comprise polycrystalline materials.

11. The apparatus of claim 10, wherein said films of selected materials comprise polycrystalline metals.

12. The apparatus of claim 1, further comprising:

means for measuring coherent transmitted electromagnetic beam energy;

means for measuring scattered transmitted electromagnetic beam energy; and

circuitry for extracting semiconductor wafer spectral emissivity based on measurements of said incident beam energy, measurements of said coherent reflected beam energy, measurements of said scattered beam energy, measurements of said coherent transmitted beam energy, and measurements of said scattered transmitted beam energy.

13. The apparatus of claim 1 wherein said fiber optic network further operates to receive electromagnetic beam energy leaving said semiconductor wafer.

14. The apparatus of claim 1 wherein said fiber optic network directs said coherent electromagnetic beam energy in a direction substantially perpendicular to said semiconductor wafer.

15. A method for measuring physical parameters of a semiconductor wafer using a coherent electromagnetic energy sensing process control device, comprising the steps of:

generating coherent electromagnetic energy;

transmitting said coherent electromagnetic energy along a fiber optic path;

directing said coherent electromagnetic energy as an electromagnetic beam in a direction substantially perpendicular to the semiconductor wafer;

measuring the amount of electromagnetic beam energy coherently reflected from the semiconductor wafer in said substantially perpendicular direction and simultaneously measuring the amount of electromagnetic beam energy scatter reflected from the semiconductor wafer surface; and

determining semiconductor wafer surface roughness based on measurements of said coherent beam of electromagnetic energy, said coherently reflected electromagnetic beam energy, and said scatter reflected electromagnetic beam energy.

16. The method of claim 15, further comprising the steps of:

measuring the amount of electromagnetic beam energy coherently transmitted through the semiconductor wafer in said perpendicular direction and measuring the amount of electromagnetic beam energy scatter transmitted through the semiconductor wafer; and

using said coherently transmitted energy measurements and said scatter transmitted energy measurements in determining semiconductor wafer surface roughness.

17. The method of claim 16 wherein said laser energy source wavelength ranges between 0.4-15 μ

m.

18. The method of claim 16 wherein said laser energy source wavelength range is approximately 1.3 μ

m.

19. The method of claim 16 wherein said laser energy source wavelength range is approximately 1.55 μ

m.

20. The method of claim 16, further comprising the step of calculating semiconductor wafer spectral emissivity based on measurements of said coherently reflected electromagnetic beam energy, said scatter reflected electromagnetic beam energy, coherently transmitted electromagnetic beam energy, and scatter transmitted electromagnetic beam energy.

21. The method of claim 15, further comprising the step of operating said coherent electromagnetic energy sensing process control device in a semiconductor wafer processing reactor.

22. The apparatus of claim 15, wherein said coherent beam of electromagnetic energy comprises a laser energy source.

23. The method of claim 15, further comprising the steps of:

receiving said coherently reflected electromagnetic beam energy using a coherent reflection sensor; and

receiving said scatter reflected electromagnetic beam energy using a scatter reflection sensor, said scatter reflection sensor including an imaging lens for focusing said scatter reflected electromagnetic energy to said scatter reflection sensor.

24. The apparatus of claim 23, wherein said coherent reflection sensor includes an imaging lens for focusing said coherently reflected electromagnetic beam energy to said coherently reflection sensor.

25. The method of claim 15, further comprising the steps of:

receiving coherently reflected electromagnetic beam energy using a coherent transmission sensor; and

receiving scatter transmitted electromagnetic beam energy using a scatter transmission sensor, said scatter transmission sensor including an imaging lens for focusing said scatter transmitted electromagnetic energy to said scatter reflection sensor.

26. The apparatus of claim 25, wherein said coherent transmission sensor includes an imaging lens for focusing said coherently transmitted electromagnetic energy to said coherent transmission sensor.

27. The method of claim 15, further comprising the step of extracting film thickness based on measurements of said semiconductor wafer surface roughness.

28. The apparatus of claim 27, wherein said film comprises a polycrystalline film.

29. The method of claim 15 and further including the step of transmitting electromagnetic energy leaving said semiconductor wafer surface along a fiber optic path prior to said measuring steps.

30. A system for semiconductor wafer processing comprising:

a semiconductor wafer fabrication reactor; and

an electromagnetic energy sensing fabrication process control device, comprising;

an energy source for producing coherent electromagnetic energy;

a fiber optic network for directing said coherent electromagnetic energy in the direction of a semiconductor wafer;

a first receive sensor element for measuring the amount of electromagnetic power coherently reflected from the semiconductor wafer surface in the specular direction;

a second receive sensor element for measuring the amount of electromagnetic power scatter reflected from the semiconductor wafer surface;

a transmit sensor element for measuring the amount of electromagnetic power coherently transmitted through the semiconductor wafer and the amount of electromagnetic power scatter transmitted through the semiconductor wafer; and

components for determining semiconductor wafer surface roughness based on measurements of said coherently reflected electromagnetic power, said scatter reflected electromagnetic power, said coherently transmitted electromagnetic power, and said scatter transmitted electromagnetic power.

31. The semiconductor wafer fabrication system of claim 30, wherein said electromagnetic energy sensing process control device operates in a semiconductor wafer processing reactor.

32. The semiconductor wafer fabrication system of claim 30, wherein said source for producing a coherent electromagnetic energy source comprises a laser energy source.

33. The system of claim 30, wherein said electromagnetic energy sensing process control device further comprises a coherent reflection sensor for receiving said coherently reflected electromagnetic power and a scatter reflection sensor for detecting said scattered reflected electromagnetic power, said scatter reflection sensor comprising an electromagnetic energy detector and an imaging lens for focusing said scattered reflected electromagnetic power to said scattered reflected electromagnetic energy detector, and said coherent reflection sensor comprising an electromagnetic energy detector and an imaging lens for focusing said coherently reflected electromagnetic power to said coherent reflected electromagnetic energy detector.

34. The semiconductor wafer fabrication system of claim 30, wherein said electromagnetic energy sensing process control device further comprises circuitry for extracting polycrystalline metal film thickness based on measurements of said semiconductor wafer surface roughness.

35. The semiconductor wafer fabrication system of claim 30, wherein said electromagnetic energy sensing process control device further comprises circuitry for extracting other polycrystalline film thickness values based on measurements of said semiconductor wafer surface roughness.

36. The semiconductor wafer fabrication system of claim 30, wherein said electromagnetic energy sensing process control device further comprises circuitry for extracting semiconductor wafer spectral emissivity based on measurements of said coherently reflected electromagnetic power, said scatter reflected electromagnetic power, said coherently transmitted electromagnetic power, and said scatter transmitted electromagnetic power.

37. The semiconductor wafer fabrication system of claim 30, wherein said electromagnetic energy sensing process control device further comprises circuitry for extracting total spectral reflectivity for a metal film versus metal film thickness for semiconductor wafer fabrication process diagnostic analysis.

38. The system of claim 30, wherein said fiber optic network further operates to receive electromagnetic energy leaving said semiconductor wafer surface.

39. The system of claim 30 wherein said fiber optic network directs said coherent electromagnetic beam energy in a direction substantially perpendicular to said semiconductor wafer.

40. A system for measuring semiconductor wafer temperature and adjusting the temperature measurements in a thermal processing reactor utilizing a heating lamp module, wherein the temperature measurement adjustments compensate for semiconductor wafer surface roughness and emissivity, comprising:

a temperature measurement device, comprising;

at least one pyrometer position with the heating lamp module between said pyrometer and the wafer;

a light pipe optically coupling said pyrometer and the wafer through the lamp module, such that said pyrometer may determine the temperature of the wafer;

a lamp power supply;

a controller for adjusting output from the lamp module based on input from said pyrometer, such that the wafer temperature may be adjusted; and

a device for measuring the semiconductor wafer surface roughness and spectral emissivity, said device comprising;

a coherent electromagnetic energy source;

components for directing coherent electromagnetic energy in the direction of the wafer;

components for measuring the amount of electromagnetic power coherently reflected from the semiconductor wafer surface in the specular direction;

components for measuring the amount of electromagnetic power scatter reflected from the semiconductor wafer surface;

components for measuring the amount of electromagnetic power coherently transmitted through the semiconductor wafer in the specular direction;

components for measuring the amount of electromagnetic power scatter transmitted through the semiconductor wafer;

circuitry for extracting wafer surface roughness and spectral emissivity based on measurements of said . coherent electromagnetic energy, said coherently reflected electromagnetic power, said scattered reflected electromagnetic power, said coherently transmitted electromagnetic power, and said scatter transmitted electromagnetic power; and

circuitry for compensating temperature measurements of said temperature measurement device for surface roughness and spectral emissivity measurements from said semiconductor wafer surface roughness and spectral emissivity device.

41. The semiconductor wafer temperature sensor and adjusting system of claim 40, wherein said semiconductor wafer surface roughness and spectral emissivity device operates within a semiconductor wafer processing reactor.

42. The semiconductor wafer temperature sensor and adjusting system of claim 40, further comprising a coherent reflection sensor for receiving said coherently reflected electromagnetic power and a scatter reflection sensor for detecting said scatter reflected electromagnetic power, said scatter reflection sensor comprising an imaging lens for focusing said scatter reflected electromagnetic power to said scatter reflection sensor, and said coherent reflection sensor comprising an imaging lens for focusing said coherently reflected electromagnetic power to said coherent reflection sensor.

43. The semiconductor wafer temperature sensor and adjusting system of claim 41, further comprising circuitry for extracting other polycrystalline film thickness values based on measurements of said semiconductor wafer surface roughness.

44. The semiconductor temperature determination and adjusting system of claim 40, wherein said coherent electromagnetic energy source comprises a laser energy source.

45. The semiconductor wafer temperature sensor and adjusting system of claim 40, further comprising a coherent reflection sensor for receiving said coherently reflected electromagnetic power and a scatter reflection sensor for detecting said scatter reflected electromagnetic power, said scatter reflection sensor comprising an imaging lens for focusing said scatter reflected electromagnetic power to said scatter reflection sensor and said coherent reflection sensor comprising an imaging lens for focusing said coherently reflected electromagnetic power to said coherent reflection sensor.

46. The semiconductor wafer temperature sensor and adjusting system of claim 40, further comprising circuitry for extracting polycrystalline metal film thickness based on measurements of said semiconductor wafer surface roughness.

47. The semiconductor wafer temperature sensor and adjusting system of claim 46, further comprising circuitry for extracting semiconductor wafer spectral emissivity based on measurements of said electromagnetic energy source, said coherently reflected electromagnetic power, said scatter reflected electromagnetic power, said coherently transmitted electromagnetic power, and said scatter transmitted electromagnetic power.

48. A sensor for semiconductor device manufacturing process control wherein said semiconductor device is on a stationary semiconductor wafer comprising:

an incident electromagnetic beam energy source;

a fiber optic network associated with said energy source for directing coherent electromagnetic beam energy in the direction of the semiconductor wafer;

a first receive sensor module for measuring electromagnetic beam energy reflected as coherent beam power from the semiconductor wafer in the specular direction and electromagnetic beam energy reflected as scattered beam power from the semiconductor wafer;

a second receive sensor module for measuring electromagnetic beam energy transmitted as coherent beam power through the semiconductor wafer in the specular direction and electromagnetic beam energy transmitted as scattered beam power through the semiconductor wafer;

circuitry for determining semiconductor wafer surface roughness based on the measurements of said beam energy reflected as coherent beam power and reflected as scattered beam power; and

circuitry for extracting semiconductor wafer spectral emissivity based on measurements of said incident beam energy, measurements of coherent reflected beam energy, measurements of scattered reflected beam energy, measurements of coherent transmitted beam energy, and measurements of scattered transmitted beam energy.