Research on the Effects of Process Parameters on Surface Roughness in Wet-Activated Silicon Direct Bonding Base on Orthogonal Experiments

  • Lei NIE
  • Huajing LI
  • Wenjing XIANG
Keywords: wafer bonding, surface hydrophilicity, wet activation, process optimization


Surface roughness is a very important index in silicon direct bonding and it is affected by processing parameters in the wet-activated process. These parameters include the concentration of activation solution, holding time and treatment temperature. The effects of these parameters were investigated by means of orthogonal experiments. In order to analyze the wafer roughness more accurately, the bear ratio of the surface was used as the evaluation index. From the results of the experiments, it could be concluded that the concentration of the activation solution affected the roughness directly and the higher the concentration, the lower the roughness. Holding time did not affect the roughness as acutely as that of the concentration, but a reduced activation time decreased the roughness perceptibly. It was also discovered that the treatment temperature had a weak correlation with the surface roughness. Based on these conclusions, the parameters of concentration, temperature and holding time were optimized respectively as NH4OH:H2O2=1:1 (without water), 70 °C and 5 min. The results of bonding experiments proved the validity of the conclusions of orthogonal experiments.