Method of preventing contamination of LED die
A method for allowing a reflective layer to abut against an edge of a metal contact while preventing contamination of a metal contact for an LED die is provided. The method includes encapsulating an electrical contact (i.e. metal contact) via with a barrier layer prior to deposition of a reflective film layer. The barrier layer encapsulates the metal contact by defining a mask pattern with a larger size than the metal contact via, which prevents the metal contact from becoming contaminated by the reflective film. This encapsulation reduces contamination of the metal contact and also reduces the voltage drop during operation of the LED die.
1. A method comprising:
providing a wafer comprising an epitaxy layer, a dielectric layer over the epitaxy layer, at least one via in the dielectric layer, and a metal contact in the at least one via;
patterning a photoresistive layer on the dielectric layer in regions that are not adjacent the at least one via;
depositing a barrier layer over exposed portions of the metal contact, the dielectric layer and the photoresistive layer;
removing the photoresistive layer and regions of the barrier layer overlaying the photoresistive layer; and
depositing a reflective layer over an entire surface of the barrier layer and the dielectric layer.
2. The method of claim 1 , wherein the removing the photoresistive layer and the regions of the barrier layer comprises performing a lift-off of the photoresistive layer and the regions of the barrier layer.
3. The method of claim 1 , wherein the reflective layer is deposited such that a lateral edge of the reflective layer abuts directly against a lateral edge of the barrier layer.
4. The method of claim 1 , further comprising roughening the reflective layer such that a roughened surface of the reflective layer a surface roughness of between 46.0 nm-50.0 nm.
5. The method of claim 1 , further comprising depositing another barrier layer on the contact before depositing the barrier layer over the metal contact and the portion of the dielectric layer adjacent the metal contact.
6. A device comprising:
an epitaxial layer;
a dielectric layer over the epitaxial layer, the dielectric layer defining at least one via;
a metal contact in the at least one via;
a barrier layer over the metal contact and a portion of the dielectric layer adjacent the metal contact; and
a reflective layer over an entire surface of the barrier layer and the dielectric layer.
7. The device of claim 6 , wherein a lateral edge of the reflective layer abuts directly against a lateral edge of the barrier layer.
8. The device of claim 6 , wherein the reflective layer contacts the dielectric layer in a region between adjacent metal contacts.
9. The device of claim 6 , wherein the metal contact comprises a gold beryllium (AuBe) compound.
10. The device of claim 6 , wherein an upper surface of the reflective layer has a surface roughness between 46.0 nm and 50.0 nm.
11. The device of claim 6 , further comprising another barrier layer between the metal contact and the barrier layer.
12. The device of claim 6 , wherein the reflective layer comprises one of Ag and Al.
13. The device of claim 6 , wherein the device is a light-emitting diode (LED) device.
14. The device of claim 6 , wherein the device is a wafer of light-emitting diode (LED) devices.
15. The device of claim 6 , wherein the epitaxy layer comprises at least one gallium phosphide (GaP) material.
16. The device of claim 6 , wherein the reflective layer is in direct contact with the barrier layer.