A bonding surface of {TAIL ~ first semiconductor substrate} 11 , and a bonding surface of second semiconductor substrate 12 are {HEAD ~ mirror} finished to provide a surface roughness of below 500 Å each 
A bonding surface of { TAIL ~ first semiconductor substrate } 11 , and a bonding surface of second semiconductor substrate 12 are { HEAD ~ mirror } finished to provide a surface roughness of below 500 Å each
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH