Automated wafer defect inspection system and a process of performing such inspection

• US 7,729,528 B2
• Filed: 08/10/2004
• Issued: 06/01/2010
• Est. Priority Date: 07/15/1998
• Status: Active Grant

• Current Assignee: Rudolph Technologies Incorporated (Onto Innovation Inc.)
• Original Assignee: Rudolph Technologies Incorporated (Onto Innovation Inc.)
• Inventors: Watkins, Cory, O'Dell, Jeffrey, Verburgt, Thomas, Harless, Mark
• Primary Examiner(s): Strege; John B
• Application Number:
  US10/915,666
• Publication Number:
  US 20050008218A1
• Time in Patent Office: 2,121 Days
• Field of Search: 382/141, 382/145, 382/147, 382/148, 382/149, 382/181, 348/87, 348/126, 356/237.3, 356/237.4, 356/237.5, 438/16, 250/559.39
• US Class Current: 382/149
• CPC Class Codes: G01N 2021/8838 Stroboscopic illumination; synchronised illumination
• CPC Class Codes: G01N 21/8803 Visual inspection measuring projectors G01B9/08
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/0696 Pulsed
• CPC Class Codes: G01N 2201/0697 Pulsed lasers
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: H01L 21/67242 Apparatus for monitoring, sorting or marking testing or measuring during manufacture H01L22/00, marks per se H01L23/544; testing individual semiconductor devices G01R31/26
• CPC Class Codes: H01L 21/67271 Sorting devices
• CPC Class Codes: H01L 21/67288 Monitoring of warpage, curvature, damage, defects or the like
• 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: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H04N 23/56 provided with illuminating means

Abstract

An automated defect inspection system has been invented and is used on patterned wafers, whole wafers, broken wafers, partial wafers, sawn wafers such as on film frames, JEDEC trays, Auer boats, die in gel or waffle packs, MCMs, etc. and is specifically intended and designed for second optical wafer inspection for such defects as metalization defects (such as scratches, voids, corrosion, and bridging), diffusion defects, passivation layer defects, scribing defects, glassivation defects, chips and cracks from sawing, solder bump defects, and bond pad area defects.

Claims

1. An automated system for inspecting a substrate, the system comprising:

a wafer test plate;

a substrate provider for providing a substrate to the test plate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, a plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a visual inspection device for visual inputting of a plurality of known good quality substrates having a user defined level of quality during training and for visual inspection of other unknown quality substrates during inspection;

an illuminator for providing short pulses of light to each of the unknown quality substrates during movement between the substrate and the visual inspection device; and

a microprocessor having processing and memory capabilities for developing a model of good quality substrate and comparing unknown quality substrates to the model.

2. The automated system of claim 1, wherein the visual inspection device is configured to capture still images of each of the unknown quality substrates during continuous movement between the substrate and the visual inspection device.

3. The automated system of claim 2, wherein the short pulses of light are synchronized with the capturing of the still images.

4. The automated system of claim 1, wherein the illuminator is configured to provide the short pulses of light based on a velocity of the movement.

5. The automated system of claim 1, wherein the illuminator is configured to provide the short pulses of light at a sequence correlating to a velocity of the movement.

6. The automated system of claim 1, wherein the illuminator comprises a brightfield illuminator positioned approximately above the wafer test plate.

7. The automated system of claim 1, wherein the illuminator comprises a darkfield illuminator positioned approximately above the wafer test plate.

8. The automated system of claim 1, wherein the illuminator comprises at least one darkfield laser positioned approximately about a periphery of the wafer test plate for providing darkfield illumination at an angle of less than about six degrees to the wafer test plate.

9. An automated method of inspecting a semiconductor substrate, the method comprising:

training a model as to parameters of a good substrate via optical viewing of multiple known good substrates;

illuminating unknown quality substrates with an illuminator, the illuminator configured to provide flashes of light to each of the unknown quality substrates during movement of the substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, a plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

inspecting the unknown quality substrates using the model, thereby identifying acceptable quality substrates; and

performing at least one processing step on the acceptable quality substrates, therby transforming the acceptable quality substrates into further processed substrates.

10. The automated method of claim 9, wherein the inspecting step comprises capturing still views of each of the unknown quality substrates during continuous movement of the substrate.

11. The automated method of claim 10, wherein the flashes of light are synchronized with the capturing of the still views.

12. The automated method of claim 9, wherein the illuminator is configured to provide the flashes of light based on a velocity of the movement.

13. The automated method of claim 9, wherein the illuminator is configured to provide the flashes of light at a sequence correlating to a velocity of the movement.

14. An automated system for inspecting a substrate, the system comprising:

a wafer test plate;

a substrate provider for providing a substrate to the test plate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a camera for capturing still images of a moving substrate;

an illuminator for providing strobe illumination to the moving substrate; and

a controller for comparing pixel data for unknown quality substrates to a model of a good quality substrate.

15. The automated system of claim 14, wherein the illuminator is configured to provide the strobe illumination based on a velocity of the moving substrate.

16. The automated system of claim 14, wherein the strobe illumination comprises short pulses of light at a sequence correlating to a velocity of the moving substrate.

17. The automated system of claim 14, wherein the strobe illumination is synchronized with the capturing of the still images.

18. The automated system of claim 14, wherein the illuminator comprises a brightfield illuminator positioned approximately above the wafer test plate.

19. The automated system of claim 14, wherein the illuminator comprises a darkfield illuminator positioned approximately above the wafer test plate.

20. The automated system of claim 14, wherein the illuminator comprises a set of low angle darkfield lasers positioned approximately about a periphery of the wafer test plate for providing darkfield illumination at an angle of less than about six degrees to the wafer test plate.

21. An automated system for inspection of a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a platform arranged for moving the substrate during inspection, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a visual inspection device adapted to capture images associated with the substrate while the substrate is in motion relative to the visual inspection device;

a strobing illuminator configured to automatically illuminate at least a portion of the substrate while the substrate is in motion to aid in capture of the images by the visual inspection device; and

a processor configured to compare the captured images to a reference model during inspection to detect defects in the substrate.

22. The automated system of claim 21, wherein the strobing illuminator comprises at least one of a brightfield illuminator, a darkfield laser and a darkfield illuminator.

23. The automated system of claim 21, wherein the visual inspection device comprises a grey-scale camera.

24. The automated system of claim 21, wherein the strobing illuminator is configured to selectively illuminate the substrate at a variable rate, wherein the variable rate is automatically adjusted to a speed associated with movement of the substrate relative to the visual inspection device.

25. An automated system for training a reference model for inspection of a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a moveable stage configured to move the substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a visual inspection device adapted to capture images associated with the substrate while the substrate is in motion relative to the visual inspection device;

a strobing illuminator operative to automatically illuminate at least a portion of the substrate while the substrate is in motion relative to the visual inspection device; and

a processor configured to create a reference model based on the images associated with at least two known quality substrates.

26. The automated system of claim 25, wherein the visual inspection device comprises a grey-scale camera.

27. An automated system for inspection of a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a moveable stage configured to move the substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a visual inspection device adapted to capture images associated with the substrate;

a strobing illuminator operative to automatically illuminate at least a portion of the substrate while the substrate is in motion relative to the visual inspection device; and

a processor configured to generate a reference model from the captured images acquired from at least two known quality substrates, and compare the captured images acquired from an unknown quality substrate to the reference model to detect defects in the unknown quality substrate.

28. The automated system of claim 27, wherein the defects comprise a set of defects associated with bumps.

29. The automated system of claim 27, wherein the visual inspection device comprises a grey-scale camera.

30. An automated method of inspecting a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the method comprising:

moving a first reference known quality substrate relative to a visual inspection device;

collecting a first image associated with the first known quality substrate while the first reference known quality substrate is in motion relative to the visual inspection device;

moving a second reference known quality substrate relative to the visual inspection device;

collecting a second image associated with the second reference known quality substrate while the second reference known quality substrate is in motion relative to the visual inspection device;

creating a reference model based on the first image and the second image;

moving an unknown quality substrate relative to the visual inspection device, wherein the unknown quality substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, a plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

automatically illuminating at least a portion of the unknown quality substrate while the unknown quality substrate is in motion relative to the visual inspection device;

collecting a set of images associated with the unknown quality substrate while at least a portion of the unknown quality substrate is illuminated and the unknown quality substrate is in motion relative to the visual inspection device; and

comparing the set of images to the reference model to detect defects in the unknown quality substrate.

31. The automated method of claim 30, wherein the first known quality substrate, the second known quality substrate and the unknown quality substrate each comprise a die.

32. An automated system for inspection of a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a means for moving the substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a means for capturing images associated with the substrate while the substrate is in motion;

a means for automatically illuminating at least a portion of the substrate while the substrate is in motion; and

a means for comparing the captured images to a reference model to detect defects in the substrate.

33. The automated system of claim 32, wherein the means for moving the substrate comprises at least one of a platform, a plate and a stage.

34. The system of claim 32, wherein the means for capturing images comprises a grey-scale camera.

35. The system of claim 32, wherein the means for automatically illuminating comprises a computer-controlled strobing illuminator.

36. The system of claim 32, wherein the means for comparing comprises at least one of a microprocessor, a computer system, a computer-like device and a digital signal processor.

37. An automated system for inspection of a substrate for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a moveable platform adapted to move the substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a robotic arm configured to provide the substrate to the moveable platform;

a brightileld illuminator configured to selectively strobe the substrate while the substrate is in motion;

a darkileld illuminator configured to selectively strobe the substrate while the substrate is in motion;

a focusing mechanism adapted to focus on a surface of the substrate;

a grey-scale camera adapted to capture images of the substrate while the substrate is in motion; and

a processor adapted to compare the images to a reference model to detect defects in the substrate.

38. The automated system of claim 37, wherein the processor is further adapted to virtually align the substrate.

39. The automated system of claim 37, wherein the reference model is based on a set of images from at least two known quality substrates.

40. The automated system of claim 37, wherein the defects comprise a set of defects associated with bumps.

41. The automated system of claim 37, wherein the brightfield strobing illuminator and darkfield strobing illuminated are configured to selectively illuminate the substrate at a variable rate, wherein the variable rate is automatically adjusted to a speed associated with movement of the substrate relative to the visual inspection device.

42. An automated system for inspection of a substrate on a film frame for defects, wherein the substrate comprises at least a portion of a wafer, the system comprising:

a platform arranged for moving the substrate during inspection, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

a visual inspection device adapted to capture images associated with the substrate while the substrate is in motion relative to the visual inspection device;

a strobing illuminator configured to automatically illuminate at least a portion of the substrate while the substrate is in motion to aid in capture of the images by the visual inspection device; and

a processor configured to compare the captured images to a reference model during inspection to detect defects in the substrate.

43. An automated method of inspecting an unknown quality substrate comprising:

moving the unknown quality substrate, wherein the unknown quality substrate comprises at least a portion of a patterned wafer mounted on a film frame;

automatically strobing the unknown quality substrate while the unknown quality substrate is in motion;

capturing images of the unknown quality substrate while the unknown quality substrate is in motion;

comparing the images to a reference model to detect defects in the unknown quality substrate and make the unknown quality substrate a known quality substrate; and

performing at least one processing step on the known quality substrate, thereby transforming the known quality substrate into a further processed substrate.

44. The automated method of claim 43, wherein the defects comprise at least one of metallization defects, diffusion defects, passivation layer defects, scribing defects, glassivation defects, sawing-related chips, sawing-related cracks, bump defects, bond pad area defects and probe area defects.

45. The automated method of claim 43, wherein the defects consist essentially of a set of defects generally at a 1+ micron level.

46. The automated method of claim 43, wherein the at least a portion of a wafer comprises a plurality of irregularly spaced die.

47. The automated method of claim 46, wherein the plurality of irregularly spaced die are sawn.

48. The automated method of claim 46, wherein the plurality of irregularly spaced die are die selected from all of the die on the at least a portion of a wafer.

49. The automated method of claim 43, wherein the rate at which the unknown quality substrate is strobed varies with respect to the velocity of the unknown quality substrate.

50. The automated method of claim 43, wherein the rate at which the unknown quality substrate is strobed varies during the inspection of the unknown quality substrate.

51. The automated method of claim 43, wherein the rate at which the unknown quality substrate is strobed varies discontinuously.

52. The automated method of claim 46, wherein the rate at which the unknown quality substrate is strobed varies in a manner that correlates to both the velocity of the unknown quality substrate and the position of the irregularly spaced die.

53. An automated method of inspecting an unknown quality substrate comprising:

moving the unknown quality substrate, wherein the substrate is selected from a group consisting of a whole patterned wafer, a sawn patterned wafer, a broken patterned wafer, at least one portion of a patterned wafer, an individual die, at least one portion of an individual die, plurality of individual die, at least one portion of a plurality of individual die, multiple die in a waffle pak, a multi-chip module (MCM), a JEDEC tray, and an Auer boat;

automatically strobing the unknown quality substrate while the unknown quality substrate is in motion varying a rate at which the unknown quality substrate is strobed during inspection, the rate at which the unknown quality substrate is strobed being at least partially correlated to both the rate at which the unknown quality substrate is moved and the relative positions of a plurality of regions of interest on the unknown quality substrate;

capturing images of at least one of the regions of interest on the unknown quality substrate while the unknown quality substrate is in motion;

comparing the images to a reference model to detect defects in the unknown quality substrate and make the unknown quality substrate a known quality substrate; and

performing at least one processing step on the known quality substrate, thereby transforming the known quality substrate into a further processed substrate.