Analysis of crack and dislocation of direct wafer bonded silicon diaphragm

Crack and dislocation of direct wafer bonded silicon diaphragm on silicon dioxide layer of silicon substrate containing cavity were analyzed. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and focused ion beam (FIB) were conducted on cracked silicon diaphragm to understand the mechanisms of crack initiation and propagation. SEM analysis results show that the crack initiated at the bottom of the silicon diaphragm and subsequently propagated toward to the top surface of the silicon diaphragm. Further FIB (focused ion beam) and TEM (transmission electron microscope) analyses show the presence of dislocations at silicon diaphragm and the bonding interface (i.e. silicon/silicon dioxide interface). Crack initiation and propagation mechanisms were discussed based on the SEM, FIB/SEM, EDX and TEM analysis results.