Study of the selectivity of porous silicon formation

Abstract

The process of the porous silicon layer formation and etching off is a new generation surface micromachining technology. The key problem of using porous silicon as a sacrificial layer is to do research on the selectivity of porous layer formation. In this paper, we will present the experimental results about which that the silicon is transformed to porous silicon in concentrated HF solution, including the relationship with current density J (mA/cm<SUP>2</SUP>), HF concentration C (wt%) and the substrate resistivity ((Omega) cm). Besides, by using implantation and epitaxial methods to change the doping level of the mask, porous silicon can be locally formed, the thickness and the undercutting may be changed by the parameters described before.