Non-reactive barrier metal for eutectic bonding process

摘要

A eutectic metal layer (e.g., gold/tin) bonds a carrier wafer structure to a device wafer structure. In one example, the device wafer structure includes a silicon substrate upon which an epitaxial LED structure is disposed. A layer of silver is disposed on the epitaxial LED structure. The carrier wafer structure includes a conductive silicon substrate covered with an adhesion layer. A layer of non-reactive barrier metal (e.g., titanium) is provided between the silver layer and the eutectic metal to prevent metal from the eutectic layer (e.g., tin) from diffusing into the silver during wafer bonding. During wafer bonding, the wafer structures are pressed together and maintained at more than 280° C. for more than one minute. Use of the non-reactive barrier metal layer allows the total amount of expensive platinum used in the manufacture of a vertical blue LED manufactured on silicon to be reduced, thereby reducing LED manufacturing cost.

主权项

1. An apparatus comprising:
a carrier; an adhesion layer next to the carrier, the adhesion layer comprising a first titanium layer that prevents migration of tin; a bonding metal layer next to the adhesion layer, the bonding metal layer comprising a tin layer; a non-reactive barrier metal layer next to the bonding metal layer, the non-reactive barrier metal layer comprising a second titanium layer that prevents migration of tin; an encapsulation layer next to the non-reactive barrier metal layer, the encapsulation layer comprising a platinum layer that prevents migration of silver; a reflective layer encapsulated by the encapsulation layer, the reflective layer comprising a silver layer; a current blocking layer next to the reflective layer; and a light emitting structure next to the current blocking layer and the reflective layer, the light emitting structure comprising an active layer between a p-type layer and an n-type layer; wherein the n-type layer comprises a first gallium-nitride (GaN) layer, a second GaN layer, and an intervening sublayer between the first GaN layer and the second GaN layer; wherein the intervening sublayer comprises an aluminum-gallium-nitride layer doped with silicon (AlGaN:Si); wherein the intervening sublayer is thinner than the first GaN layer, and the intervening sublayer is thinner than the second GaN layer.