Investigation of bonding with micro structures starting from double layers to multi-layers

The technique of multi-layers' direct bonding with micro structures was investigated by both theoretical analysis and experimental validation. The adopted method of chemical energy activation in silicon wafer surface was hydrophilic treatment. The adopted bonding process was to firstly pre-bond wafers in bonding machine and then carry out high temperature annealing in annealing furnace. In the process, the parameters in pre-bonding procedure decided whether the bonding could succeed eventually. The three main parameters (temperature, pressure, time) in pre-bonding procedure were elaborately analyzed using orthogonal experiments, significantly reducing the time of experiments. The infrared images of bonded wafers were analyzed by silicon-silicon bonding analysis software prepared by the research group to calculate the bonding rate. Applying the best pre-bonding process parameters concluded by experiments, the bonding rate of multi-layers reached 86.652 7%.