Influential factors in low-temperature direct bonding of silicon dioxide

We investigate the influential factor in low-temperature bonding of silicon dioxide. Two surfaces were formed by thermal oxidation and plasma-enhanced chemical vapor deposition with 50 nm thick. Surface characterization by atomic force microscopy. Wafer cleaning by piranha, surface-activated by oxygen plasma, pre-bonding at room temperature and post-bonding anneal by 100-400 degrees Celsius in 0.03 Pascal for 1 hour. Bonding area was tested by dicing machine that PECVD silicon dioxide showed weak bonding, whereas oxide from thermal oxidation showed good results between 200-400 degrees Celsius. Thus surface roughness and annealing temperature are an influential factor of low-temperature bonding of silicon dioxide.