METHOD FOR CUTTING SEMICONDUCTOR WAFERS

• US 20030060022A1
• Filed: 08/30/2001
• Published: 03/27/2003
• Est. Priority Date: 08/24/2001
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Chua, Tan kok, Chye, Chew Beng, Chuan, Tan Hock, Peng, Neo Chee, Har, Lim Guek, Seng, Ho Kian
• Granted Patent: US 6,576,531 B2
• Time in Patent Office: Days
• US Class Current: 438/460
• CPC Class Codes: B23D 59/002 for the position of the saw blade B27B5/36 and B27B9/02 take precedence
• CPC Class Codes: B28D 5/022 by cutting with discs or wheels
• CPC Class Codes: B28D 5/029 with a plurality of cutting blades
• CPC Class Codes: H01L 21/3043 Making grooves, e.g. cutting
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: Y10S 83/906 Chip making
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/088 Responsive to tool detector or work-feed-means detector
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/263 With means to apply transient nonpropellant fluent material to tool or work
• CPC Class Codes: Y10T 83/855 Relative to another element

Abstract

Improperly mounted wafer saw blades can damage wafers cut or diced with the blades. Embodiments of this invention employ sensors to measure a distance to the blade to help indicate if the blade is improperly mounted. In one method of the invention, a the distance to the blade face is measured as the blade is rotated and a variance in this measured distance is determined. If the variance is no greater than a predetermined maximum, the blade may be used to cut the wafer. In one apparatus of the invention, a wafer saw include a blade and a sensor. The sensor is adapted to monitor a distance to a face of the rotating blade. A processor coupled to the sensor may indicate if the distance to the face of the blade as it rotates deviates too far from a baseline position of the blade face.

Claims

1. A method of cutting a semiconductor substrate, comprising:

positioning the semiconductor substrate with respect to a blade of a saw;

rotating the blade in a first spaced position wherein a peripheral cutting edge of the blade is spaced from the semiconductor substrate;

measuring a distance to a face of the blade as the blade is rotated in the first spaced position and determining a first variance in the measured distance as the blade is rotated; and

, if the first variance is no greater than a predetermined maximum variance,

contacting the semiconductor substrate with the peripheral cutting edge of the blade and translating the blade with respect to the semiconductor substrate to cut at least partially through the semiconductor substrate.

2. The method of claim 1 further comprising terminating rotation of the blade if the first variance is greater than the predetermined maximum variance.

3. The method of claim 1 further comprising generating a warning if the first variance is greater than the predetermined maximum variance.

4. The method of claim 1 wherein the first variance is determined without contacting the blade with a flow of cooling liquid.

5. The method of claim 4 wherein the blade is contacted with a flow of cooling liquid when the blade is cutting the semiconductor substrate.

6. The method of claim 1 wherein the blade is rotated in the first position prior to contacting the semiconductor substrate with the blade.

7. The method of claim 1 further comprising positioning the blade in a second spaced position after cutting the semiconductor substrate, the peripheral cutting edge of the blade being spaced from the semiconductor substrate when the blade is in the second spaced position;

rotating the blade in the second spaced position without cutting the semiconductor substrate;

measuring the distance to the face of the blade as the blade is rotated in the second spaced position and determining a second variance.

8. The method of claim 7 wherein the first spaced position is the same position as the second spaced position.

9. The method of claim 7 further comprising contacting the semiconductor substrate with the peripheral cutting edge of the blade if the second variance is no greater than the predetermined maximum variance.

10. The method of claim 7 further comprising terminating rotation of the blade if the second variance is greater than the predetermined maximum variance.

11. The method of claim 7 further comprising generating a warning if the second variance is greater than the predetermined maximum variance.

12. A method of operating a semiconductor substrate saw, comprising:

rotating a blade of the saw without contacting the blade with a flow of liquid;

monitoring a distance to a face of the blade as the blade rotates;

determining a first baseline distance to the face of the blade and determining a first deviation from the baseline distance;

indicating an error if the first deviation is greater than a predetermined maximum deviation; and

, only if the error is not indicated,

making a first cut at least partially through a semiconductor substrate with the blade while contacting the blade with a flow of liquid.

13. The method of claim 12 further comprising terminating rotation of the blade if an error is indicated.

14. The method of claim 12 further comprising generating a warning if an error is indicated.

15. The method of claim 12 wherein the first cut is made by contacting the semiconductor substrate with a peripheral cutting edge of the blade.

16. The method of claim 15 wherein the liquid comprises water.

17. The method of claim 12 wherein the distance to the face of the blade is monitored when the blade is in a first position, the blade in the first position being spaced from the semiconductor substrate.

18. The method of claim 12 further comprising positioning the blade in a spaced position with a peripheral cutting edge of the blade spaced from the semiconductor substrate;

rotating the blade in the spaced position without cutting the semiconductor substrate;

monitoring a distance to the face of the blade as the blade is rotated in the spaced position; and

determining a second baseline distance to the face of the blade and determining a second deviation from the baseline distance.

19. The method of claim 18 further comprising making a second cut at least partially through the semiconductor substrate only if the second deviation is no greater than the predetermined maximum deviation.

20. The method of claim 18 further comprising terminating rotation of the blade if the second deviation is greater than the predetermined maximum deviation.

21. The method of claim 18 further comprising generating a warning if the second deviation is greater than the predetermined maximum deviation.

22. A method of exchanging a blade of a semiconductor substrate saw, comprising:

removing a used blade from a blade mount carried on a shaft of the saw;

mounting a new blade on the blade mount;

prior to contacting a semiconductor substrate with the new blade, rotating the new blade;

prior to contacting the semiconductor substrate with the new blade, monitoring a distance to a face of the new blade as the blade rotates;

prior to contacting the semiconductor substrate with the new blade, determining a baseline distance to the face of the blade and determining a deviation from the baseline distance;

prior to contacting the semiconductor substrate with the new blade, indicating an error if the deviation exceeds a predetermined maximum deviation; and

, only if the error is not indicated,

making a cut at least partially through the semiconductor substrate with the blade.

23. A method of exchanging a blade of a multiple-blade semiconductor substrate saw which includes a used first blade and a second blade, the used first blade being carried on a first shaft for rotation with the first shaft and the second blade being carried on a second shaft for rotation with the second shaft, the method comprising:

removing the used first blade from the first blade mount;

mounting a new first blade on the first blade mount;

rotating the new first blade in a first position;

monitoring a distance from a first sensor to a face of the new first blade as the new first blade rotates in the first position, the first sensor being associated with the second shaft;

indicating whether a first variance in the monitored distance as the new first blade is rotated is greater than a predetermined maximum first variance; and

,

if the first variance is not greater than the maximum first variance,

contacting a semiconductor substrate with the new first blade and with the second blade.

24. The method of claim 23 further comprising moving the second shaft and the first sensor laterally with respect to the first shaft, thereby changing the distance from the first sensor to the face of the new first blade.

25. The method of claim 23 further comprising terminating rotation of the blade if the first variance is greater than the predetermined maximum variance.

26. The method of claim 23 further comprising generating a warning if the first variance is greater than the predetermined maximum variance.

27. The method of claim 23 wherein the first variance is determined without contacting the blade with a flow of cooling liquid.

28. The method of claim 27 wherein the blade is contacted with a flow of cooling liquid when the blade is cutting the semiconductor substrate.

29. The method of claim 28 wherein the cooling liquid comprises water.

30. The method of claim 23 wherein the blade is rotated in the first position prior to contacting the semiconductor substrate with the blade.

31. The method of claim 23 further comprising cutting at least partially through the semiconductor substrate with the new first blade and with the second blade.

32. The method of claim 31 further comprising, after cutting the semiconductor substrate, rotating the new first blade in a second position, monitoring the distance from the first sensor to the face of the new first blade as the new first blade rotates in the second position, and indicating whether a second variance in the monitored distance as the new first blade is rotated is greater than a predetermined maximum second variance.

33. The method of claim 32 wherein the first position differs from the second position.

34. The method of claim 32 further comprising moving the second shaft and the first sensor laterally with respect to the first shaft, thereby changing the distance from the first sensor to the face of the new first blade, after monitoring the first distance and before monitoring the second distance.

35. The method of claim 23 further comprising removing the second blade from the second mount;

mounting a new second blade on the second blade mount;

rotating the new second blade;

monitoring a distance from a second sensor to a face of the new second blade as the new second blade rotates, the second sensor being associated with the first shaft; and

indicating whether a second variance in the measured distance as the new second blade is rotated in the second position is greater than a predetermined maximum second variance.

36. The method of claim 35 wherein the semiconductor substrate is contacted with the first blade and with the second blade only if the first variance is not greater than the maximum first variance and the second variance is not greater than the maximum second variance.

37. The method of claim 35 wherein the maximum first variance is equal to the maximum second variance and the semiconductor substrate is contacted with the first blade and with the second blade only if neither the first variance nor the second variance is greater than the maximum first variance.

38. A semiconductor wafer saw, comprising:

a carrier for a microelectronic workpiece;

a driver;

a first shaft coupled to the driver and extending opposite the carrier, the first shaft having a first axis;

a first blade mount carried adjacent an end of the shaft for rotation with the first shaft;

a first blade carried by the first blade mount for rotation with the first blade mount, the first blade having a face and a peripheral cutting edge;

a sensor spaced from the first blade and oriented toward the face of the first blade, the sensor maintaining a fixed angular position with respect to the first axis as the first blade is rotated with the shaft, the sensor being adapted to measure a distance to the face of the first blade; and

a processor operatively coupled to the sensor, the processor being adapted to indicate if the distance to the face of the first blade deviates more than a predetermined permitted deviation from a baseline distance to the face of the first blade as the blade rotates.

39. The semiconductor wafer saw of claim 38 wherein the sensor comprises a CCD laser displacement sensor.

40. The semiconductor wafer saw of claim 38 wherein the first shaft is adapted to move transversely with respect to the sensor.

41. The semiconductor wafer saw of claim 38 wherein the sensor is carried by a support and the first shaft is moveable vertically with respect to the support.

42. The semiconductor wafer saw of claim 41 wherein the first shaft is moveable transversely with respect to the support to vary the baseline distance.

43. The semiconductor wafer saw of claim 38 wherein first shaft is moveable with respect to the sensor to vary the baseline distance.

44. The semiconductor wafer saw of claim 38 further comprising a cooling liquid supply line positioned to deliver a cooling fluid, the processor being adapted to control flow through the supply line to terminate flow of cooling fluid when the sensor monitors a the distance to the face of the first blade.

45. A semiconductor wafer saw, comprising:

a carrier for a microelectronic workpiece;

a first spindle extending opposite the carrier, the first spindle having a first axis;

a first blade carried by the first spindle for rotation with the first spindle, the first blade having a face and a peripheral cutting edge;

a second spindle extending opposite the carrier, the second spindle having a second axis;

a second blade carried by the second spindle for rotation with the second spindle, the second blade having a face and a peripheral cutting edge;

a first sensor carried by the second spindle and adapted to measure a first distance to the face of the first blade, the first sensor maintaining a fixed angular position with respect to the first axis as the first blade rotates about the first axis;

a second sensor carried by the first spindle and adapted to measure a second distance to the face of the second blade, the second sensor maintaining a fixed angular position with respect to the second axis as the second blade rotates about the second axis; and

a processor operatively coupled to the first and second sensors, the processor being adapted to indicate if variation of the first distance as the first blade rotates exceeds a predetermined maximum first variation and to indicate if variation of the second distance as the second blade rotates exceeds a predetermined maximum second variation.

46. The semiconductor wafer saw of claim 45 wherein the first axis coincides with the second axis.

47. The semiconductor wafer saw of claim 46 wherein one or both of the first and second spindles are adapted for movement transversely along the coincident first and second axes.

48. The semiconductor wafer saw of claim 45 wherein the first spindle is adapted for movement transversely along the first axis, movement of the first spindle along the first axis varying a baseline distance of the first sensor from the face of the first blade.

49. The semiconductor wafer saw of claim 48 wherein the second spindle is adapted for movement transversely along the second axis.

50. The semiconductor wafer saw of claim 45 wherein the second spindle is adapted for movement transversely along the second axis, movement of the second spindle along the second axis varying a baseline distance of the second sensor from the face of the second blade.

51. The semiconductor wafer saw of claim 45 wherein the first spindle is adapted for movement transversely along the first axis and the second spindle is adapted for movement transversely along the second axis.

52. The semiconductor wafer saw of claim 45 wherein the first sensor comprises a CCD laser displacement sensor.

53. The semiconductor wafer saw of claim 45 wherein the second sensor comprises a CCD laser displacement sensor.

54. The semiconductor wafer saw of claim 45 wherein the first and second spindles are each moveable vertically with respect to the carrier.

55. The semiconductor wafer saw of claim 45 further comprising a cooling liquid supply line positioned to deliver a cooling fluid, the processor being adapted to control flow through the supply line to terminate flow of cooling fluid when the sensor monitors a the distance to the face of the first blade.