METHOD AND APPARATUS FOR IMPROVED LASER SCRIBING OF OPTO-ELECTRIC DEVICES

• US 20120211477A1
• Filed: 02/20/2011
• Published: 08/23/2012
• Est. Priority Date: 02/20/2011
• Status: Active Grant

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Inventors: Chacin, Juan, Chyr, Irving, Halderman, Jonathan
• Granted Patent: US 8,735,772 B2
• Time in Patent Office: Days
• US Class Current: 219/121.69
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/035 Aligning the laser beam automatically B23K26/042
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/0853 Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
• 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: H01S 5/0201 Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth

Abstract

Disclosed are laser scribing systems for laser scribing semiconductor substrates with backside coatings. In particular these laser scribing systems laser scribe opto-electric semiconductor wafers with reflective backside coatings so as to avoid damage to the opto-electric device while maintaining efficient manufacturing. In more particular these laser scribing systems employ ultrafast pulsed lasers at wavelength in the visible region and below in multiple passes to remove the backside coatings and scribe the wafer.

Claims

1. An improved method for scribing opto-electric devices on a substrate with a laser scribing system, said substrate having a frontside, said frontside having streets and a backside, said backside having a surface having a coating, said improvements comprising:

providing said laser scribing system with an ultrafast pulsed laser having first and second laser pulse parameters;

removing said coating from said backside surface of said substrate in regions generally aligned with said frontside streets of said substrate using said ultrafast pulsed laser and said first laser pulse parameters without causing substantial damage to said substrate, and;

scribing said substrate in regions generally aligned with said frontside streets of said substrate using said ultrafast pulsed laser and said second laser pulse parameters.

2. The method of claim 1 wherein said substrate is one of sapphire, silicon, germanium, diamond, or ceramic.

3. The method of claim 1 wherein said ultrafast pulsed laser is one of a fiber laser, diode-pumped solid state laser or gas laser.

4. The method of claim 1 wherein said first and second laser pulse parameters include a wavelength equal to or less than about 560 nm.

5. The method of claim 1 wherein said first and second laser pulse parameters include laser power of between about 0.5 W and about 10 W.

6. The method of claim 1 wherein said first and second laser pulse parameters include a pulse repetition rate between about 75 kHz and about 1,000 kHz.

7. The method of claim 1 wherein said first and second laser pulse parameters include a scan speed of between about 75 mm/s and about 500 mm/s.

8. The method of claim 1 wherein said first laser pulse parameters include a focal spot offset of about 0 μ

m and one pass.

9. The method of claim 1 wherein said second laser pulse parameters include focal spot offsets of between about 0 and about −

30 μ

m and two passes.

10. The method of claim 1 wherein said first laser pulse parameters include a focal spot offset of between about 15 μ

m and about 50 μ

m and two passes.

11. The method of claim 1 wherein said second laser pulse parameters include a focal spot offset of between about 0 μ

m and about −

30 μ

m and one pass.

12. An improved system for scribing opto-electric devices on a substrate with a laser scribing system, said substrate having a frontside, said frontside having streets and a backside, said backside having a surface having a coating, said improvements comprising:

an ultrafast pulsed laser having first and second laser pulse parameters wherein said first laser pulse parameters remove said coating from said backside surface of said substrate in regions generally aligned with said frontside streets and said second laser pulse parameters scribe said substrate in regions generally aligned with said frontside streets of said substrate.

13. The system of claim 12 wherein said substrate is one of sapphire, silicon, germanium, diamond, or ceramic.

14. The system of claim 12 wherein said ultrafast pulsed laser is one of a fiber laser, diode-pumped solid state laser or gas laser.

15. The system of claim 12 wherein said first and second laser pulse parameters include a wavelength equal to or less than about 560 nm.

16. The system of claim 12 wherein said first and second laser pulse parameters include laser power of between about 0.1 W and about 10 W.

17. The system of claim 12 wherein said first and second laser pulse parameters include a pulse repetition rate between about 75 kHz and 1,000 kHz.

18. The system of claim 12 wherein said first and second laser pulse parameters include a scan speed of between about 20 mm/s and about 500 mm/s.

19. The system of claim 12 wherein said first laser pulse parameters include a focal spot offset of about 0 μ

m and one pass.

20. The system of claim 12 wherein said second laser pulse parameters include focal spot offsets of between about 0 and about −

30 μ

m and two passes.

21. The system of claim 12 wherein said first laser pulse parameters include a focal spot offset of between about 15 μ

m and about 50 μ

m and two passes.

22. The system of claim 12 wherein said second laser pulse parameters include a focal spot offset of between about 0 μ

m and about −

30 μ

m and one pass.