Scribing sapphire substrates with a solid state UV laser

• US 6,580,054 B1
• Filed: 07/30/2002
• Issued: 06/17/2003
• Est. Priority Date: 06/10/2002
• Status: Expired due to Term

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: New Wave Research, Inc. (MKS Instruments Incorporated)
• Inventors: Pinkham, Scott, Liu, Jenn, Middlebusher, Duane, Oltrogge, Steven, Huang, Jih-Chuang, Lucero, Antonio, Dere, Dan, Fang, Pei Hsien, Liu, Kuo-Ching
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): JOHNSON, JONATHAN J
• Application Number:
  US10/208,484
• Time in Patent Office: 322 Days
• Field of Search: 219/121.68, 219/121.67, 219/121.69, 219/121.7, 219/121.71, 219/121.72, 219/121.83, 219/121.82, 264/400, 156/272.8
• US Class Current: 219/121.68
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/36 Wood or similar materials
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/073 Shaping the laser spot
• 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 5/0011 with preliminary treatment, e.g. weakening by scoring
• 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: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01S 5/0201 Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth
• CPC Class Codes: H01S 5/0213 Sapphire, quartz or diamond based substrates
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

A process and system scribe sapphire substrates, by performing the steps of mounting a sapphire substrate, carrying an array of integrated device die, on a stage such as a movable X-Y stage including a vacuum chuck; and directing UV pulses of laser energy directed at a surface of the sapphire substrate using a solid-state laser. The pulses of laser energy have a wavelength below about 560 nanometers, and preferably between about 150 in 560 nanometers. In addition, energy density, spot size, and pulse duration are established at levels sufficient to induce ablation of sapphire. Control of the system, such as by moving the stage with a stationary beam path for the pulses, causes the pulses to contact the sapphire substrate in a scribe pattern at a rate of motion causing overlap of successive pulses sufficient to cut scribe lines in the sapphire substrate.

Claims

1. A method for manufacturing die from a sapphire substrate, comprising;

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration to couple laser energy directly into said sapphire substrate by absorption sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate.

2. The method of claim 1, including separating die defined by the scribe pattern from the sapphire substrate.

3. The method of claim 1, including causing overlap of successive pulses.

4. The method of claim 1, wherein the wavelength is between about 150 and 560 nanometers.

5. The method of claim 1, wherein the repetition rate is between about 10 kHz and 50 kHz.

6. The method of claim 1, wherein said energy density is between about 10 and 100 joules per square centimeter, said pulse duration is between about 10 and 30 nanoseconds, and the spot size is between about 5 and 25 microns.

8. The method of claim 1, including generating the pulses of laser energy using a Q-switched solid state laser.

9. The method of claim 1, including:

during causing the pulses to impact the sapphire substrate in a scribe pattern, detecting edges of the sapphire substrate, and in response to detected edges, preventing said pulses from being directed off of the substrate.

12. The method of claim 1, including generating the pulses of laser energy using a Q-switched Nd:

YAG laser.

13. The method of claim 1, including generating the pulses of laser energy using a Q-switched Nd:

YVO₄ laser.

14. The method of claim 1, including generating the pulses of laser energy using a diode pumped, Q-switched Nd:

YAG laser operating at a third harmonic wavelength of about 355 nanometers.

15. The method of claim 1;

including generating the pulses of laser energy using a diode pumped, Q-switched Nd;

YVO₄ laser operating at a third harmonic wavelength of about 355 nanometers.

16. The method of claim 1, wherein the spot size is between 5 and 15 microns.

17. The method of claim 1, including causing overlap of successive pulses, and wherein the overlap is in a range from 50 to 99 percent.

20. The method of claim 1, wherein the stage comprises a movable x-y stage, and said causing the pulses to impact the sapphire substrate in a scribe pattern, includes moving the substrate on the x-y stage.

7. A method for manufacturing die from a sapphire substrate, comprising;

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate,

wherein the sapphire substrate has a thickness, and the scribe lines are cut to a depth of more than about one half said thickness.

10. A method for manufacturing die from a sapphire substrates, comprising:

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate, and including;

placing the substrate on an adhesive tape prior to causing the pulses to impact the sapphire substrate in a scribe pattern; and

preventing said pulses from impacting the adhesive tape.

11. A method for manufacturing die from a sapphire substrate, comprising:

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate, and including;

placing the substrate on an adhesive tape prior to causing the pulses to impact the sapphire substrate in a scribe pattern;

detecting edges of the sapphire substrate during said causing the pulses to impact the sapphire substrate in a scribe pattern, and in response to detected edges, preventing said pulses from impacting the adhesive tape.

18. A method for manufacturing die from a sapphire substrate, comprising:

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate,

wherein the substrate has an active surface and a back side, and including placing the active surface of the substrate on an adhesive tape, and mounting the substrate on the stage to direct the pulses to the back side of the substrate.

19. A method for manufacturing die from a sapphire substrate, comprising:

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire; and

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate, wherein the substrate has an active surface and a back side, and including causing the laser pulses to impact the back side.

21. A method for manufacturing die from a sapphire substrate, comprising:

laying out and forming integrated devices in an array on an active surface of the sapphire substrate, wherein individual die are separated by streets having a width of about 25 microns or less;

mounting the sapphire substrate with the active surface down on a stage;

directing pulses of laser energy at a back surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration to couple laser energy directly into said sapphire substrate by absorption sufficient to induce ablation of sapphire;

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate; and

separating die defined by the scribe pattern from the sapphire substrate.

22. A method for manufacturing die from a sapphire substrate, comprising;

mounting the sapphire substrate on a stage;

directing pulses of laser energy at a surface of the sapphire substrate, the pulses having a wavelength, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire;

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate; and

controlling polarization of the laser pulses with respect to direction of scribe lines in the scribe pattern.

23. The method of claim 22, wherein the wavelength is less than about 560 nanometers.

24. The method of claim 22, including using a solid state UV laser to generate the pulses.

25. The method of claim 22, wherein the scribe pattern includes scribe lines parallel to first and second axes, including controlling the polarization so that the polarization is linear and arranged in a first direction for scribe lines parallel to the first axis and arranged in a second direction for scribe lines parallel to the second axis.

26. The method of claim 22, including separating die defined by the scribe pattern from the sapphire substrate.

27. The method of claim 22, including causing overlap of successive pulses.

28. The method of claim 22, wherein the wavelength is between about 150 and 560 nanometers.

29. The method of claim 22, wherein the repetition rate is between about 10 kHz and 50 kHz.

30. The method of claim 22, wherein said energy density is between about 10 and 100 joules per square centimeter, said pulse duration is between about 10 and 30nanoseconds, and the spot size is between about 5 and 25 microns.

31. The method of claim 22, wherein the sapphire substrate has a thickness, and the scribe lines are cut to a depth of more than about one half said thickness.

32. The method of claim 22, including generating the pulses of laser energy using a Q-switched solid state laser.

33. The method of claim 22, including:

during causing the pulses to impact the sapphire substrate in a scribe pattern, detecting edges of the sapphire substrate, and in response to detected edges, preventing said pulses from being directed off of the substrate.

34. The method of claim 22, including:

placing the substrate on an adhesive tape prior to causing the pulses to impact the sapphire substrate in a scribe pattern; and

preventing said pulses from impacting the adhesive tape.

35. The method of claim 22, including:

placing the substrate on an adhesive tape prior to causing the pulses to impact the sapphire substrate in a scribe pattern;

detecting edges of the sapphire substrate during said causing the pulses to impact the sapphire substrate in a scribe pattern, and in response to detected edges, preventing said pulses from impacting the adhesive tape.

36. The method of claim 22, including generating the pulses of laser energy using a Q-switched Nd:

YAG laser.

37. The method of claim 22, including generating the pulses of laser energy using a Q-switched Nd:

YVO₄ laser.

38. The method of claim 22, including generating the pulses of laser energy using a diode pumped, Q-switched Nd:

YAG laser operating at a third harmonic wavelength of about 355 nanometers.

39. The method of claim 22, including generating the pulses of laser energy using a diode pumped, Q-switched Nd:

YVO₄ laser operating at a third harmonic wavelength of about 355 nanometers.

40. The method of claim 22, wherein the spot size is between 5 and 15 microns.

41. The method of claim 22, including causing overlap of successive pulses, and wherein the overlap is in arrange from 50 to 99 percent.

42. The method of claim 22, wherein the substrate has an active surface and a back side, and including placing the active surface of the substrate on an adhesive tape, and mounting the substrate on the stage to direct the pulses to the back side of the substrate.

43. The method of claim 22, wherein the substrate has an active surface and a back side, and including causing the laser pulses to impact the back side.

44. The method of claim 22, wherein the stage comprises a movable x-y stage, and said causing the pulses to impact the sapphire substrate in a scribe pattern, includes moving the substrate on the x-y stage.

45. The method of claim 22, wherein said controlling polarization includes aligning polarization of the pulses parallel to the scribe line being scribed.

46. A method for manufacturing die from a sapphire substrate, comprising:

laying out and forming integrated devices in an array on an active surface of the sapphire substrate, wherein individual die are separated by streets having a width of about 25 microns or less;

mounting the sapphire substrate with the active surface down on a stage;

directing pulses of laser energy at a back surface of the sapphire substrate using a solid state laser, the pulses having a wavelength below about 560 nanometers, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of sapphire;

causing the pulses to impact the sapphire substrate in a scribe pattern to cut scribe lines in the sapphire substrate;

controlling polarization of the pulses so that the pulses are linearly polarized in a direction parallel to the scribe lines being scribed; and

separating die defined by the scribe pattern from the sapphire substrate.

47. The method of claim 46, including generating the pulses of laser energy using a Q-switched Nd:

YAG laser.

48. The method of claim 46, including generating the pulses of laser energy using a Q-switched Nd:

YVO₄ laser.

49.The method of claim 46, including generating the pulses of laser energy using a diode pumped, Q-switched Nd;

YAG laser operating at a third harmonic wavelength of about 355 nanometers.

49. The method of claim 46, including generating the pulses of laser energy using a diode pumped, Q-switched Nd:

YO₄ laser operating at a third harmonic wavelength of about 355 nanometers.