Stabilized transient liquid phase metal bonding material for hermetic wafer level packaging of mems devices

A method of making a transient liquid phase (TLP) metal bonding material, the method comprising:

• electroplating a base metal over at least a portion of a first substrate to form a base metal layer having a surface roughness (Ra) of between about 0.001 to 500 nm;
• electroplating a metal fuse on the base metal layer and forming a metal fuse layer of between 200 and 400 Å;
• and
• electroplating a first terminal metal onto the metal fuse layer and forming a terminal metal layer to form the TLP metal bonding material, wherein the TLP metal bonding material is stable at room temperature for at least a predetermined period of time.

A method of forming a hermetic bond, the method comprising:

• in contact with a second material, placing a transient liquid phase (TLP) metal bonding material including a first substrate, a base metal layer, a metal fuse layer and a first terminal layer, wherein the base metal layer has a surface roughness (Ra) of between about 0.001 to 500 nm and is disposed over at least a portion of the first substrate, wherein the first terminal metal layer forms the external surface of the TLP metal bonding material and is positioned between the base metal layer and the first terminal metal layer, wherein the metal fuse layer has a thickness of between about 200 to 400 Å, and wherein the second material includes a second substrate and a second terminal metal layer;
• heating the TLP metal bonding material;
• and
• melting the first terminal metal layer to form a first molten metal that dissolves the metal fuse layer, wherein the first molten metal diffuses into the first terminal metal layer and the second terminal metal layer to form an intermetallic compound that is thermally stable for at least a predetermined period of time, and wherein the intermetallic compound includes the hermetic bond between the TLP metal bonding material and the second material;
• wherein the TLP metal bonding material is stable at room temperature for at least a predetermined period of time.