Method of etching and singulating a cap wafer

摘要

A method of forming a capped die forms a cap wafer having a top side and a bottom side. The bottom side is formed with 1) a plurality of device cavities having a first depth, and 2) a plurality of second cavities that each have a greater depth than the first depth. At least some of the plurality of second cavities each generally circumscribe at least one of the device cavities. The method then secures the cap wafer to a device wafer in a manner that causes a plurality of the device cavities each to circumscribe at least one of circuitry and structure on the device wafer. Next, the method removes at least a portion of the top side of the cap wafer to expose the second cavities. This forms a plurality of caps that each protect the noted circuitry and structure.

主权项

1. A method of forming a capped die, the method comprising:
providing a cap wafer having a top side and a patterned hard mask layer on a bottom side of the wafer, the patterned hard mask layer having open areas to define locations for device cavities and second cavities; applying a mask over the bottom side of the wafer, thereby covering the patterned hard mask layer; after applying the mask, etching the wafer to remove wafer material from areas defining the second cavities; removing the mask; after removing the mask, performing a step of etching, wherein removal of wafer material is prevented by the hard mask layer at areas covered by the hard mask layer and removal of wafer material takes place in areas not covered by the hard mask layer so as to form a plurality of device cavities in the bottom side of the cap wafer, the device cavities having a first depth, and to further deepen a plurality of second cavities in the bottom side, such that each of the second cavities has a greater depth than the first depth, and wherein at least some of the device cavities are circumscribed by at least one of the second cavities; securing the cap wafer to a device wafer, a plurality of the device cavities each enclosing at least one of circuitry and movable structure on the device wafer; backgrinding a portion of the top side of the cap wafer thereby exposing the second cavities to form a plurality of caps that each protect the at least one of circuitry and movable structure.