Progress and Mechanism of Cu Assisted Chemical Etching of Silicon in a Low Cu2+ Concentration Region

Silicon wafer with a nanostructured porous layer on top surface was obtained with Cu(NO3)(2)-HF-H2O2 aqueous solution treatment in a low Cu2+ concentration region (0.001 M-0.02 M). The influences of different recipes concentrations on silicon surface morphology and the average etching rate were investigated. Craters and pores structures are successfully formed on the silicon surface layer. No copper particles are observed from the SEM images of as-prepared silicon surface with pores. The mechanism of forming nanostructured porous layer on silicon surface without metal nanoparticles was discussed. The morphology evolution of Si surface and the transition from craters to pores in the low Cu2+ concentration region were investigated. (C) 2015 The Electrochemical Society. All rights reserved.