Apparatus and method for singulating semiconductor wafers

• US 20020031899A1
• Filed: 04/30/2001
• Published: 03/14/2002
• Est. Priority Date: 06/08/1999
• Status: Active Grant

• Current Assignee: Advanced Dicing Technologies Ltd. (GL Tech Co., Ltd.)
• Original Assignee: Kulicke & Soffa Investments, Inc.
• Inventors: Manor, Ran
• Granted Patent: US 6,420,245 B1
• Time in Patent Office: Days
• US Class Current: 438/460
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0093 combined with mechanical machining or metal-working covered by other subclasses than B23K combined welding or cutting procedures or apparatus B23K28/02
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B28D 1/221 by thermic methods
• CPC Class Codes: B28D 5/0011 with preliminary treatment, e.g. weakening by scoring
• 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: B28D 5/04 by tools other than rotary type, e.g. reciprocating tools B28D5/0005 takes precedence
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D
• 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: H01S 5/0201 Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth

Abstract

A method and apparatus for singulating semiconductor wafers is described. The method comprises the steps of aiming a laser beam at a layer placed over the substrate; absorbing energy from the laser beam into the layer; forming scribe lines in the layer by scanning the laser beam across the layer; and cutting through the substrate along the scribe lines with a saw blade to singulate the wafer. The apparatus includes a laser placed over the coating layer of the substrate, and a saw blade mounted over a surface of the substrate. The coating layer has a first absorption coefficient relative to a wavelength of the laser and the semiconductor substrate has a second absorption coefficient less than the first absorption coefficient. Energy from the laser beam is absorbed into the coating layer to form scribe lines therein, and the saw blade cuts through the substrate along the scribe lines.

Claims

1. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a wavelength of the laser beam;

(b) absorbing energy from the laser beam into the layer based on the first absorption coefficient;

(c) forming a first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser beam, the second direction substantially orthogonal to the first direction;

(e) cutting through the substrate along the second set of scribe lines with a saw blade to form a respective first set of kerfs; and

(f) cutting through the substrate along the first set of scribe lines with the saw blade to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient by about an order of an order of magnitude.

2. The method according to claim 1, wherein the laser emits infrared radiation.

3. The method according to claim 2, wherein the wavelength of the laser is between about 1.2 and 15 microns.

4. The method according to claim 2, wherein the wavelength of the laser is between about 9 and 11 microns.

5. The method according to claim 2, wherein the wavelength of the laser is one of i) 9.3, ii) 9.6 and iii) 10.6 microns.

6. The method according to claim 1, wherein the layer is a plurality of layers and the second absorption coefficient of the substrate is less than each respective absorption coefficient of the plurality of layers.

7. The method according to claim 1, wherein a width of the laser scribe lines is greater than that of the saw blade kerfs.

8. The method according to claim 1, wherein each one of i) the first set of scribe lines and the first set of kerfs are substantially parallel to one another, and ii) each one of the second set of scribe lines and second set of kerfs are substantially parallel to one another.

9. The method according to claim 1, wherein the laser beam is formed by a CO2 laser.

10. The method according to claim 1, wherein the scribe lines have a depth equal to a depth of the layer.

11. The method according to claim 1, wherein the scribe lines have a depth no greater than a depth of the layer.

12. The method according to claim 1, wherein the substrate is silicon based and the layer over the substrate is other than silicon based.

13. The method according to claim 1, wherein the second absorption coefficient is less than the first absorption coefficient by at least an order of magnitude.

16. The method according to claim 15, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.

18. The method according to claim 17, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.

20. The method according to claim 19, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.

14. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a wavelength of the laser beam;

(b) absorbing energy from the laser beam into the layer based on the first absorption coefficient;

(c) forming a first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser beam, the second direction substantially orthogonal to the first direction;

(e) cutting through the substrate along the second set of scribe lines with a saw blade to form a respective first set of kerfs; and

(f) cutting through the substrate along the first set of scribe lines with the saw blade to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient by about an order of an order of magnitude.

15. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser beam into only the layer;

(c) forming a first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser, the second direction substantially orthogonal to the first direction;

(e) cutting through the substrate along the second set of scribe lines with a saw blade to form a respective first set of kerfs, and

(f) cutting through the substrate along the first set of scribe lines with the saw blade to form a respective second set of kerfs,

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength from the laser beam, the first absorption coefficient greater than the second absorption coefficient.

17. A method for dicing a semiconductor substrate using a laser and a saw blade, the method comprising the steps of:

(a) aiming the laser at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser into the layer;

(c) forming a first set of scribe lines in a first direction in the layer by scanning the laser across the layer, the laser removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser across the layer and removing at least a portion of the layer with the laser, the second direction substantially orthogonal to the first direction;

(e) cutting a first set of kerfs in the substrate with the saw blade along the second set of scribe lines; and

(f) cutting a second set of kerfs in the substrate with the saw blade along the first set of scribe lines,

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength of the laser beam, the first absorption coefficient greater than the second absorption coefficient by about an order of an order of magnitude, and the first set of kerfs and the second set of kerfs form a plurality of dice from the substrate.

19. A method for dicing a semiconductor substrate using a laser and a saw blade, the method comprising the steps of:

(a) aiming the laser at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser into the layer;

(c) forming a first scribe line in a first direction in the layer by scanning the laser across the layer, the laser removing at least a portion of the layer;

(d) cutting a first kerf in the substrate with the saw blade along the first scribe line;

(e) forming a further first scribe line in the first direction over the substrate, the further scribe line substantially parallel to the first scribe line;

(f) cutting a further first kerf in the substrate with the saw blade along the further first scribe line;

(g) repeating steps (e) and (f) in the first direction until the entire substrate is scribed and cut;

(h) forming a second scribe line in a second direction in the layer by scanning the laser across the layer and removing at least a portion of the layer, the second direction substantially orthogonal to the first direction;

(i) cutting a second kerf in the substrate with the saw blade along the second scribe line;

(j) forming a further second scribe line in the second direction on the substrate, the further second scribe line substantially parallel to the second scribe line;

(k) cutting a further second kerf in the substrate with the saw blade along the further second scribe line; and

(l) repeating steps (j) and (k) in the second direction until the entire substrate is scribed and cut,

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength of the laser beam, the first absorption coefficient greater than the second absorption coefficient by about an order of magnitude, and the first kerf, the further first kerfs, the second kerf and the further second kerfs form a plurality of dice from the substrate.

21. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a plurality of individual laser beams at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a respective wavelength of the each of the plurality of laser beams;

(b) absorbing energy from the plurality of laser beams into the layer based on the first absorption coefficient;

(c) forming a respective first set of scribe lines for each of the plurality of lasers beams in a first direction in the layer by scanning the plurality of laser beams across the layer, the plurality of laser beams removing at least a portion of the layer;

(d) forming a respective second set of scribe lines in a second direction in the layer by scanning the plurality of laser beams across the layer and removing at least a portion of the layer,;

(e) cutting through the substrate along the second set of scribe lines with a saw blade to form a respective first set of kerfs; and

(f) cutting through the substrate along the first set of scribe lines with the saw blade to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient.

22. The method according to claim 21, wherein the second direction substantially orthogonal to the first direction.

23. The method according to claim 21, wherein the plurality of laser beams are generated by respective laser sources.

24. The method according to claim 21, wherein the plurality of laser beams are two laser beams.

25. The method according to claim 24, wherein the two laser beams are generated by splitting a single laser beam emitted from a single laser source

28. The method according to claim 27, wherein the substrate has a second absorption coefficient relative to the respective wavelength of each of the plurality of laser beams, the second absorption coefficient less than the first absorption coefficient.

30. The apparatus of claim 29, wherein the second absorption coefficient less than the first absorption coefficient by about an order of magnitude.

31. The apparatus of claim 29, wherein the second absorption coefficient less than the first absorption coefficient by at least an order of magnitude.

32. The apparatus according to claim 29, wherein the laser is a CO2 laser.

26. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a wavelength of the laser beam;

(b) absorbing energy from the laser beam into the layer based on the first absorption coefficient;

(c) forming a first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser beam, the second direction substantially orthogonal to the first direction,

(e) cutting through the substrate along the second set of scribe lines with to form a respective first set of kerfs, each spindle holding and rotating a respective saw blade, and

(f) cutting through the substrate along the first set of scribe lines with the two spindles to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient.

27. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a plurality of individual laser beams at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a respective wavelength of each of the plurality of laser beams;

(b) absorbing energy from the plurality of laser beams into the layer based on the first absorption coefficient;

(c) forming a respective first set of scribe lines for each of the plurality of lasers beams in a first direction in the layer by scanning the plurality of laser beams across the layer, the plurality of laser beams removing at least a portion of the layer;

(d) forming a respective second set of scribe lines in a second direction in the layer by scanning the plurality of laser beams across the layer and removing at least a portion of the layer with the plurality of laser beams;

(e) forming a respective first set of kerfs by cutting through the substrate along the second set of scribe lines with two spindles, each spindle holding and rotating a respective saw blade; and

(f) forming a respective second set of kerfs by cutting through the substrate along the first set of scribe lines with the two spindles each one holding and rotating a saw blade.

29. An apparatus for dicing a semiconductor substrate having a coating layer thereon, the apparatus comprising:

an infrared laser placed over the coating layer of the substrate, the coating layer having a first absorption coefficient relative to a wavelength of the laser and the semiconductor substrate having a second absorption coefficient less than the first absorption coefficient; and

a spindle mounted over a surface of the substrate, the spindle holding and rotating a saw blade,

wherein energy from the laser beam is absorbed into the coating layer based on a first absorption coefficient to form at least one scribe line therein, and the saw blade cuts through the substrate along the at least one scribe line.

33. An apparatus for dicing a semiconductor substrate having a coating layer thereon, the apparatus comprising:

at least two infrared laser beams placed over the coating layer of the substrate, the coating layer having a first absorption coefficient relative to a wavelength of each of the at least two laser beams and the semiconductor substrate having a second absorption coefficient less than the first absorption coefficient; and

a spindle mounted over a surface of the substrate, the spindle holding and rotating a saw blade,

wherein energy from the at least two laser beams is absorbed into respective portions of the coating layer based on a first absorption coefficient to form respective scribe lines therein, and the saw blade cuts through the substrate along the respective scribe lines.

34. The apparatus according to claim 33, wherein the at least two laser beams are formed from one laser source.

35. The apparatus according to claim 33, wherein each of the at least two laser beams are formed from respective laser sources.

38. The apparatus according to claim 37, wherein the at least two laser beams are formed from one laser source.

39. The apparatus according to claim 38, wherein each of the at least two laser beams are formed from respective laser sources.

36. An apparatus for dicing a semiconductor substrate having a coating layer thereon, the apparatus comprising:

an infrared laser placed over the coating layer of the substrate, the coating layer having a first absorption coefficient relative to a wavelength of the laser and the semiconductor substrate having a second absorption coefficient less than the first absorption coefficient; and

at least two spindles mounted over a surface of the substrate, each spindle holding and rotating one saw blade,

wherein energy from the laser beam is absorbed into the coating layer based on a first absorption coefficient to form a plurality of scribe lines therein, and the at least two saw blades separately cut through the substrate along respective ones of the plurality of scribe lines.

37. An apparatus for dicing a semiconductor substrate having a coating layer thereon, the apparatus comprising:

at least two infrared laser beams placed over the coating layer of the substrate, the coating layer having a first absorption coefficient relative to a wavelength of each of the at least two laser beams and the semiconductor substrate having a second absorption coefficient less than the first absorption coefficient; and

two spindles mounted over a surface of the substrate, each spindle holding and rotating one saw blade,

wherein energy from the at least two laser beams is absorbed into the coating layer based on a first absorption coefficient to form a respective plurality of scribe lines therein, and the two dicing blades separately cut through the substrate along respective ones of the plurality of scribe lines.

40. An apparatus for dicing a semiconductor substrate having a coating layer, the apparatus comprising:

means for forming at first set of scribe lines in a first direction in the layer and removing at least a portion of the layer;

means for forming a second set of scribe lines in a second direction in the layer and removing at least a portion of the layer in a substantially orthogonal direction to the first set of scribe lines,

means for cutting through the substrate along the second set of scribe lines to form a respective first set of kerfs, and

means for cutting through the substrate along the first set of scribe lines to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to a wavelength of the forming means, the second absorption coefficient less than the first absorption coefficient by about an order of an order of magnitude.

41. An apparatus for dicing a semiconductor substrate having a coating layer, the apparatus comprising:

means for forming a first scribe line in a first direction in only the coating layer;

means for cutting a first kerf in the substrate along the first scribe line;

means for forming a further first scribe line in the first direction in only the coating layer, the further scribe line substantially parallel to the first scribe line;

means for cutting a further first kerf in the substrate along the further first scribe line;

means for forming a second scribe line in a second direction in only the coating layer, the second direction substantially orthogonal to the first direction;

means for cutting a second kerf in the substrate along the second scribe line;

means for forming a further second scribe line in only the coating layer in the second direction on the substrate, the further second scribe line substantially parallel to the second scribe line; and

means for cutting a further second kerf in the substrate along the further second scribe line;

wherein the coating layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength of the forming means, the first absorption coefficient greater than the second absorption coefficient by about an order of magnitude, and the first kerf, the further first kerfs, the second kerf and the further second kerfs form a plurality of dice from the substrate.

42. An system for dicing a semiconductor substrate having a coating layer, the system comprising:

a scribing apparatus including;

i) means for forming at first set of scribe lines in a first direction in the layer and removing at least a portion of the layer; and

ii) means for forming a second set of scribe lines in a second direction in the layer and removing at least a portion of the layer in a substantially orthogonal direction to the first set of scribe lines, and

a dicing apparatus including;

i) means for cutting through the substrate along the second set of scribe lines to form a respective first set of kerfs, and

ii) means for cutting through the substrate along the first set of scribe lines to form a respective second set of kerfs,

wherein the substrate has a second absorption coefficient relative to a wavelength of the forming means, the second absorption coefficient less than the first absorption coefficient by about an order of an order of magnitude.

43. An system for dicing a semiconductor substrate having a coating layer thereon, the system comprising:

an infrared laser placed over the coating layer of the substrate, the coating layer having a first absorption coefficient relative to a wavelength of the laser and the semiconductor substrate having a second absorption coefficient less than the first absorption coefficient; and

a spindle mounted over a surface of the substrate, the spindle holding and rotating a saw blade,

wherein energy from the laser beam is absorbed into the coating layer based on a first absorption coefficient to form at least one scribe line therein, and the saw blade cuts through the substrate along the at least one scribe line.

44. The system according to claim 43, wherein the laser and the spindle are collocated with one another.