Successive etching processes form a plurality of partially etched cavities extending from {HEAD ~ a front surface} of {TAIL ~ the cap wafer} into the cap wafer  
Successive etching processes form a plurality of partially etched cavities extending from { HEAD ~ a front surface } of { TAIL ~ the cap wafer } into the cap wafer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH