Method and system for dual stretching of wafers for isolated segmented chip scale packages
View Patent ↗Described herein is a method and system for dual stretching of wafers to create isolated segmented chip scale packages. A wafer having an array of light-emitting diodes (LEDs) is scribed into LED segments, where each LED segment includes a predetermined number of LEDs. The scribed wafer is placed on a stretchable substrate or tape. The tape is stretched and a layer of optically material is placed in the separation gaps. The stretched wafer is scribed on a LED level. The tape is stretched and another layer of optically opaque material is placed in the separation gaps. The same or different optically opaque material can be used for the layers. The two layers of optically opaque material are formed to provide electrical connectivity between the LEDs in each LED segment. In an implementation, each segment or LED is individually addressable.
1. A method for dual stretching of a wafer, the method comprising:
scribing a patterned substrate along outlines between devices on the wafer;
stretching tape carrying the wafer to break the patterned substrate along the scribed outlines;
after breaking the wafer along the outlines, scribing the patterned substrate along interior lines of each device on the wafer;
stretching the tape carrying the wafer to break the patterned substrate along the scribed interior lines;
filling gaps, created when the patterned substrate is broken along the scribed interior lines, with an opaque material that is opaque to visible wavelengths to form side portions; and
dicing the patterned substrate along the scribed outlines to form segmented devices after the side portions are formed.
2. The method of claim 1 , wherein the devices comprise light emitters.
3. The method of claim 2 , wherein the segmented devices comprise segmented matrix light emitters.
4. The method of claim 3 , further comprising depositing patterned phosphor on each of the segmented matrix light emitters.
5. The method of claim 3 , wherein, after stretching the tape to break the patterned substrate along the scribed interior lines, a separation between the light emitters is larger than a separation between the segmented matrix light emitters.
6. The method of claim 1 , further comprising:
transferring the patterned substrate that has been broken along the scribed interior lines to a sputter compliant carrier; and
filling the gaps by sputtering metal as the opaque material to form side contacts.
7. The method of claim 1 , further comprising filling the gaps by depositing metal as the opaque material to form side contacts, the metal being deposited by at least one of sputtering, an anisotropic grow process with lift-off or a three-dimensional printing electrodeposition.
8. The method of claim 7 , further comprising filling the gaps by filling the gaps in only one direction to form the side contacts.
9. The method of claim 8 , wherein:
the depositing the metal comprises depositing a plurality of metal layers, and
the method further comprises depositing an insulation layer in the only one direction between the metal layers to provide insulation between the metal layers.
10. The method of claim 7 , further comprising depositing, at least one of between the devices before the metal is deposited or between the segmented devices after the metal is deposited, another opaque material that is opaque to the visible wavelengths.
11. The method of claim 10 , wherein a depth of the other opaque material is selected to ensure optical isolation between the segmented devices.
12. The method of claim 10 , wherein the other opaque material comprises Titanium Oxide embedded in silicone or dielectric layers forming a distributed Bragg reflector (DBR).
13. The method of claim 10 , wherein a particle size of the other opaque material is selected to permit flow into the gaps by capillary forces.
14. The method of claim 13 , further comprising allowing the other opaque material to harden or cure after having flowed into the gaps.
15. The method of claim 1 , further comprising forming, by patterned metal deposition, at least one of top contact pads on the segmented devices or bottom contact pads on which the segmented devices are formed.
16. A system comprising:
a scriber configured to scribe a patterned substrate along outlines between sets of light emitting diodes (LEDs) on a wafer to form a first scribed wafer and, after the patterned substrate is broken along the outlines, scribe the patterned substrate along inlines between the LEDs in at least one of the sets of LEDs on the wafer to form a second scribed wafer;
a stretching platform configured to, in a first stretching, stretch tape on which the first scribed wafer is retained to break the patterned substrate along the outlines and, in a second stretching, stretch the tape to break the patterned substrate along the inlines;
a deposition chamber configured to deposit the optically opaque material on the wafer after at least one of the first stretching or the second stretching, the optically opaque material configured to optically isolate at least one of the sets of LEDs or LEDs;
a cutter configured to dice the wafer into LED packages after the optically opaque material has hardened; and
a controller communicatively coupled to, and configured to control, the scriber, the stretching platform, the deposition chamber, and the cutter.
17. The system of claim 16 , wherein the deposition chamber is further configured to deposit patterned phosphor on each of the LEDs prior to the cutter dicing the wafer into the LED packages.
18. The system of claim 16 , wherein the deposition chamber is further configured to form side contacts of the LEDs by deposition of metal, the metal being deposited by at least one of sputtering, an anisotropic grow process with lift-off or a three-dimensional printing electrodeposition.
19. The system of claim 16 , wherein the optically opaque material comprises Titanium Oxide embedded in silicone or dielectric layers forming a distributed Bragg reflector (DBR).
20. The system of claim 16 , wherein a particle size of the optically opaque material is selected to permit flow into the gaps by capillary forces.