After being bonded to the device wafer , {HEAD ~ the cap wafer} is thinned from the back surface until the back surface of the cap wafer reaches {TAIL ~ the partially etched cavities}  
After being bonded to the device wafer , { HEAD ~ the cap wafer } is thinned from the back surface until the back surface of the cap wafer reaches { TAIL ~ the partially etched cavities }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH