Wafer level hermetic bond using metal alloy with keeper layer

Systems and methods for forming an encapsulated device include a hermetic seal which seals an insulating environment between two substrates, one of which supports the device. The hermetic seal is formed by an alloy of two metal layers, one deposited on a first substrate and the other deposited on the second substrate. At least one of the substrates may include a raised feature formed under at least one of the metal layers. One of the metal layer may have a diffusion barrier layer and a "keeper" layer formed thereover, wherein the keeper layers keeps the metal confined to a particular area. By using such a "keeper" layer, the substrate components may be heated to clean their surfaces, without activating or spending the bonding mechanism.