Application of Multi-step Diffusion Process for Large Thickness Structural Layer Fabrication

摘要

A novel method,multi-step diffusion,has been put forth in this paper,which divides conventional diffusion process into two relatively short periods remaining cumulative duration of diffusion the same.The two periods are performed continuously and each diffusion period includes one predeposition and drive-in respectively.Comparing with conventional two-step diffusion method,multi-step diffusion could bring silicon substrate larger amount of boron dopants and possesses the potential to trap dopants in a certain depth,so that it is possible to obtain larger effective junction depth (boron concentration≥5×1019/cm3).The verification experiment shows the same result.In the experiment,21 μm thick heavily boron-doped layer is obtained through the novel method,while the layer thickness mentioned in references is less than 15 μm using conventional two-step method under the same diffusion condition.