Morphological evolution of III–V semiconductors and SiO2 during low energy electron enhanced dry etching

Evolution of surface morphologies of GaAs, GaP, InP, GaN, and SiO2 during dry etching is studied. Etching was carried out in Cl2/H2/Ar plasmas with electron enhancement. No structural damage was introduced during etching. Etched surface morphologies were observed with scanning electron microscopy and roughness values were obtained using atomic force microscope. Depending on binding energies, each material showed a different morphology evolution and final surface. Materials with low binding energies (GaAs, GaP, and InP) form pits or ridges early, and become rougher over time. Increasing electron flux to the surface overcomes the tendency to roughen and produces very smooth surfaces. Materials with high binding energies (GaN, SiO2) do not form pits or ridges early. They quickly form and maintain extremely smooth surfaces with little dependence on electron flux.