Light-emitting diode chip structures with reflective elements
A light-emitting diode (LED) chip structure with a cup-like reflective element is provided. The LED chip structure comprises a substrate, an isolation element and a mesa including an LED surrounded by the isolation element. The isolation element comprises an upper isolation part and a lower isolation part. The lower isolation part is positioned in the substrate and the upper isolation part protrudes from a surface of the substrate. A reflective layer is disposed on a sidewall of the upper isolation part, and a bottom of the reflective layer does not contact the mesa. The cup-like reflective element at least includes the isolation element with the reflective layer.
1. A light-emitting diode (LED) chip structure, comprising:
a substrate;
an isolation element, comprising
an upper isolation part and a lower isolation part, wherein the lower isolation part is positioned in the substrate and the upper isolation part protrudes from a surface of the substrate;
a reflective layer disposed on a sidewall of the upper isolation part; and
a mesa including an LED component surrounded by the isolation element, wherein a bottom portion of the reflective layer does not contact the mesa;
wherein an entire area of a top surface and a sidewall of the mesa, and a top surface and the sidewall of the upper isolation part are directly or indirectly covered by a seamless conductive layer.
2. The LED chip structure according to claim 1 , wherein the reflective layer is disposed on the sidewall and the top surface of the upper isolation part, and a bottom of the reflective layer extends from the isolation element to the mesa.
3. The LED chip structure according to claim 1 , wherein a dielectric layer is disposed at a bottom of the sidewall of the mesa, and the dielectric layer is covered by the bottom portion of the reflective layer.
4. The LED chip structure according to claim 1 , wherein a height of the upper isolation part is higher than a height of the lower isolation part.
5. The LED chip structure according to claim 1 , wherein a bottom width of the upper isolation part is equal to or wider than a top width of the lower isolation part.
6. The LED chip structure according to claim 5 , wherein the bottom width of the upper isolation part is longer than the top width of the lower isolation part and shorter than twice the top width of the lower isolation part, two protrusions are formed at each bottom end of the upper isolation part, and a width of each of the two protrusions is less than half of the top width of the lower isolation part.
7. The LED chip structure according to claim 5 , wherein, in a side view, a cross section of the upper isolation part is a trapezoid and a cross section of the lower isolation part is an inverted trapezoid, a bottom of the upper isolation part covering a top of the lower isolation part.
8. The LED chip structure according to claim 5 , wherein the upper isolation part and the lower isolation part are axisymmetric and co-axial.
9. The LED chip structure according to claim 1 , wherein a height of the upper isolation part is higher than a height of the mesa, relative to a surface of the substrate, and a tilt angle of the sidewall of the upper isolation part is greater than a tilt angle of the sidewall of the mesa, relative to an axis normal to the surface of the substrate.
10. The LED chip structure according to claim 9 , wherein the tilt angle of the sidewall of the mesa is smaller than 45°, and the tilt angle of the sidewall of the upper isolation part is greater than 45°.
11. The LED chip structure according to claim 3 , wherein the dielectric layer covers the top surface and the sidewall of the mesa, the top surface of the mesa including an area free of the dielectric layer.
12. The LED chip structure according to claim 3 , wherein the dielectric layer is transparent to light emitted from the LED chip structure.
13. The LED chip structure according to claim 3 , wherein the dielectric layer comprises one or more of silicon-containing dielectric layer, aluminum-containing dielectric layer or titanium-containing dielectric layer.
14. The LED chip structure according to claim 13 , wherein the silicon-containing dielectric layer comprises an oxide or nitride of silicon, the aluminum-containing dielectric layer comprises an oxide of aluminum, and the titanium-containing dielectric layer comprises an oxide of titanium.
15. The LED chip structure according to claim 14 , wherein the oxide of titanium is Ti 3 O 5 .
16. The LED chip structure according to claim 1 , wherein the reflective layer includes a multi-layered structure.
17. The LED chip structure according to claim 16 , wherein the multi-layered structure comprises a stack of one or more reflective material layers and one or more dielectric material layers.
18. The LED chip structure according to claim 1 , wherein the reflective layer comprises one or more metallic conductive materials with a high reflectance above 80%.
19. The LED chip structure according to claim 18 , wherein the one or more metallic conductive materials comprise one or more of aluminum, gold or silver.
20. The LED chip structure according to claim 1 , wherein the seamless conductive layer is transparent to light emitted from the LED chip structure.
21. The LED chip structure according to claim 1 , wherein the isolation element comprises photosensitive dielectric material.
22. The LED chip structure according to claim 21 , wherein the photosensitive dielectric material is SU-8 or photosensitive polyimide (PSPI).
23. The LED chip structure according to claim 1 , wherein the substrate comprises a semiconductor wafer and a bonding metal layer on top of the semiconductor wafer.