US Patent 7534636 Lids for wafer-scale optoelectronic packages

A method for forming a lid for a wafer-scale package includes (1) forming a cavity in a substrate, (2) forming an oxide layer over the cavity and over a bond area around the cavity on the substrate, (3) forming a reflective layer over the oxide layer, (4) forming a barrier layer over the reflective layer, (5) etching a portion of the barrier layer down to a portion of the reflective layer over the bond area, and (6) forming a solder layer on the portion of the reflective layer. The reflective layer can be a titanium-platinum-gold metal stack and the barrier layer can be a titanium dioxide layer.