Abstract: There is a thin layer of native oxide between two directly bonded silicon wafers.The silicon extracts impurity from the oxide,thus drastically decreasing the impurity concentration at the interface of SiO2-Si.Based on the modified model of silicon direct bonding,an expression of impurity distribution is derived and verified by theory and experiment.Finally,it is found that the total impurity in silicon with oxide is much less than that without oxide,which decreases the junction depth of p-n+ junction.

Key words: silicon direct bonding,  extractive effect,  native oxide