A Raman study of InSb etched by reactive ion beam etching using a CH4/H2/N2plasma generated by electron cyclotron resonance is presented. The evolution of the LO, 2LO phonon and phonon–plasmon coupled modes has been studied using resonant Raman spectra in different configurations. Results indicate an increase of the carrier density by a factor of about 60 and a decrease of the built‐in potential due to the plasma process. The combination of both evolutions results in a prevalence of the electric field induced scattering upon the defect induced scattering mechanism. ©1996 American Institute of Physics.