LED THIN-FILM DEVICE PARTIAL SINGULATION PRIOR TO SUBSTRATE THINNING OR REMOVAL

• US 20150064808A1
• Filed: 03/29/2013
• Published: 03/05/2015
• Est. Priority Date: 04/05/2012
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Wei, Frank
• Granted Patent: US 9,847,445 B2
• Time in Patent Office: Days
• US Class Current: 438/5
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Abstract

LED dies are partially singulated while on an unthinned depth growth substrate. Slots are made through the streets separating the LED dies, but not through the growth substrate, leaving the now separated LED dies on the growth substrate. A secondary support is attached to the LED dies on the opposite surface from the growth substrate, and the growth substrate is thinned or removed, leaving the LED dies on the secondary support. Because the LED dies are separated while on the unthinned growth substrate, the likelihood of distortion before slicing is virtually eliminated, and the width of the streets between the LED dies may be correspondingly reduced.

Claims

1. A method comprising:

forming light emitting device (LED) dies on a substrate, with streets between the LED dies;

forming a slot through the streets without completely penetrating through the substrate; and

,

after the slicing;

attaching a flexible secondary support to the LED dies on the substrate;

thinning or removing the substrate; and

singulating the LED dies.

2. The method of claim 1, including applying a wavelength conversion layer over the LED dies before singulating the LED dies.

3. The method of claim 2, wherein the wavelength conversion layer is a preformed sheet of wavelength conversion material.

4. The method of claim 2, including testing the LED dies and sorting the LED dies after singulation based on the testing.

5. The method of claim 4, including selecting the wavelength conversion layer material based on the testing of the LED dies.

7. The method of claim 1, including stretching the flexible film to provide additional space between the LED dies and applying a wavelength conversion layer over the LED dies before singulating the LED dies.

8. The method of claim 1, wherein the slicing includes laser cutting, and the singulating includes mechanical sawing.

9. The method of claim 1, wherein the secondary support includes a sacrificial layer that is formed over the LED dies.

11. The method of claim 1, wherein singulating the LED dies includes removing the secondary support from the LED dies.

12. The method of claim 1, including finishing a light emitting surface of the LED dies before singulating the LED dies.

14. The item of claim 11, wherein the plurality of slots include laser cuts through the plurality of layers.

15. The item of claim 11, wherein the growth substrate is sapphire.

16. The method of claim 1, wherein the singulation is performed by the thinning step.

6. (canceled)

10. (canceled)

13. An item of manufacture comprising:

a growth substrate,

a plurality of layers formed on the growth substrate, including at least an n-type layer,

an active layer, and a p-type layer, and

a plurality of slots arranged to extend through the plurality of layers and through a portion of the growth substrate to permit singulation by thinning the substrate,

wherein the plurality of slots serve to segregate the plurality of layers into a plurality of isolated light emitting die structures upon the growth structures.