TRENCHED SUBSTRATE FOR CRYSTAL GROWTH AND WAFER BONDING

• US 20090267083A1
• Filed: 04/28/2008
• Published: 10/29/2009
• Est. Priority Date: 04/28/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Cui, Jie
• Granted Patent: US 8,664,747 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 33/007 comprising nitride compounds

Abstract

A substrate for a light emitting diode (LED) can have one or more trenches formed therein so as to mitigate stress build up within the substrate due to mismatched thermal coefficients of expansion between the substrate and layers of material, e.g., semiconductor material, formed thereon. In this manner, the likelihood of damage to the substrate, such as cracking thereof, is substantially mitigated.

Claims

1. A substrate for an LED, the substrate comprising at least one trench formed therein so as to mitigate stress within the substrate.

2. The substrate as recited in claim 1, wherein the substrate is defined by a wafer.

3. The substrate as recited in claims 1, wherein the substrate comprises sapphire.

4. The substrate as recited in claims 1, wherein the trenche(s) are generally linear.

5. The substrate as recited in claims 1, wherein the trenche(s) are curved.

6. The substrate as recited in claims 1, wherein the trenches(s) define a cross-hatched pattern.

7. The substrate as recited in claims 1, wherein the trenches(s) define a concentric circle pattern.

8. The substrate as recited in claims 1, wherein the trenche(s) define a regular pattern.

9. The substrate as recited in claims 1, wherein the trenche(s) define an irregular pattern.

10. The substrate as recited in claims 1, wherein the trenche(s) are formed upon one side of the substrate.

11. The substrate as recited in claims 1, wherein the trenches are formed upon two sides of the substrate.

12. The substrate as recited in claims 1, wherein a depth of the trenche(s) is between approximately ⅙

and approximately ½

of the thickness of the substrate.

13. The substrate as recited in claims 1, wherein a depth of the trenche(s) is approximately ⅓

of the thickness of the substrate.

14. The substrate as recited in claims 1, wherein the trenche(s) are generally rectangular in cross-section.

15. The substrate as recited in claims 1, wherein the trenche(s) are generally u-shaped in cross-section.

16. The substrate as recited in claims 1, wherein the trenche(s) are generally v-shaped in cross-section.

17. The substrate as recited in claims 1, wherein the trenche(s) extend along at least one crystal lattice direction.

18. The substrate as recited in claims 1, wherein the trenche(s) extend along a plurality of crystal lattice directions.

19. The substrate as recited in claims 1, wherein:

a diameter of the substrate is between approximately ¼

inch and approximately twelve inches;

a thickness of the substrate is between approximately 100 microns and four millimeters;

a width of the trenche(s) is between approximately one micron and approximately 100 microns; and

a distance between the trenches is between approximately 100 microns and approximately 2 millimeters.

20. The substrate as recited in claims 1, wherein:

a diameter of the substrate is approximately two inches;

a thickness of the substrate is approximately 400 microns;

a width of the trenche(s) is approximately 20 microns; and

a distance between the trenches is approximately 200 microns.

21. A device comprising:

a substrate;

a material formed upon the substrate; and

at least one trench formed in the material so as to mitigate stress therein.

22. The device as recited in claim 21, wherein the material has a thickness of between approximately 0.1 micron and approximately four inches.

23. The device as recited in claim 21, wherein the material has a thickness of approximately 10 microns.

24. A method for making LEDs, the method comprising forming at least one trench in a substrate so as to mitigate stress build up within the substrate.

25. The method as recited in claim 24, wherein the trench is formed by laser ablation.

26. The method as recited in claim 24, wherein the trench is formed by electron beam etching.

27. The method as recited in claim 24, wherein the trench is formed by a sawing.

28. The method as recited in claim 24, wherein the trench is formed by chemical etching.