Method of preventing contamination of LED die
View Patent ↗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:
(a) providing a wafer comprising an epitaxy layer and a dielectric layer with openings having metal contacts;
(b) depositing a barrier layer on the metal contacts and the dielectric layer;
(c) depositing a patterned photoresistive layer on the barrier layer in regions of the wafer overlaying the metal contact;
(d) depositing a reflective layer on the patterned photoresistive layer and the barrier layer; and
(e) removing the patterned photoresistive layer including portions of the reflective layer overlaying the patterned photoresistive layer.
2. The method of claim 1 , wherein the barrier layer is formed as a patterned barrier layer.
3. The method of claim 1 , wherein the barrier layer is formed by lift-off patterning or wet-etching.
4. The method of claim 1 , wherein a lateral edge of the reflective layer abuts directly against a lateral edge of the barrier layer.
5. The method of claim 1 , wherein a top surface of the reflective layer and a top surface of the barrier layer are coplanar in a region of the wafer adjacent to the metal contact.
6. The method of claim 1 , wherein step (c) is performed by lift-off patterning, wet-etching, or lithography.
7. The method of claim 1 , wherein the metal contact is formed from a gold beryllium (AuBe) compound.
8. The method of claim 1 , wherein the reflective layer includes mobile atoms of silver (Ag) or aluminum (Al).