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.