Time dependence study of the anisotropic etching of silicon by electrochemical impedance spectroscopy and atomic force microscopy

Marina Serantoni, Vincent J. Cunnane

    Research output: Contribution to journalArticlepeer-review

    5 Citations (Scopus)

    Abstract

    A study on the etching of monocrystalline silicon p(100) was carried out in 2 M KOH solution at 50°C in the dark using electrochemical and surface analysis techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). Two different surface pre-treatments were used. The study was carried out at three different potentials: negative to the open circuit potential (ocp): -1.8 V saturated calomel reference electrode (SCE); near-ocp: -1.42 V (SCE); positive to the ocp: -1.18 V (SCE). From electrochemical experiments it was clear that a fundamental feature in the study of silicon etching was a time dependence. The surface of the silicon working-electrode, which is smooth at the beginning of the etching becomes rough due to the formation of pyramidal hillocks. After about 20 min the CVs remain constant, indicating that a steady state has been reached on the surface. The Nyquist plots change in dimension and shape with time and as well show a steady state after about 20 min of etching. The EIS experimental data have been fitted using an equivalent circuit containing a constant phase element and a Warburg element (W). A diffusion coefficient for electro-active species was found to be of the order of 10-12 cm2 s-1. This low value is indicative of hindrance to the diffusion process due to the possible presence of polymeric species such as silicate reaction products on the silicon surface.

    Original languageEnglish
    Pages (from-to)49-67
    Number of pages19
    JournalJournal of Electroanalytical Chemistry
    Volume548
    Issue numberSUPPL.
    DOIs
    Publication statusPublished - 22 May 2003

    Keywords

    • AFM
    • EIS
    • Pre-treatments
    • Silicon etching
    • Surface states

    Fingerprint

    Dive into the research topics of 'Time dependence study of the anisotropic etching of silicon by electrochemical impedance spectroscopy and atomic force microscopy'. Together they form a unique fingerprint.

    Cite this