LOW ION ENERGY ELECTRON-CYCLOTRON-RESONANCE ETCHING OF INP USING A CL-2/N-2 MIXTURE

The low-energy (about 30 eV) ion etching of InP with an excellent vertical sidewall profile, smooth surface, and a high etch rate (more than 1000 Angstrom/min) has been demonstrated in an electron cyclotron resonance plasma using a Cl-2/N-2 mixture. Surface analysis by x-ray photoelectron spectroscopy and plasma diagnostics by optical emission spectroscopy suggest that the etching mechanism is dominated by the reduction of Cl neutral radical density by N-2 dilution and the formation of InN and P3N5 due to the reaction between the atomic nitrogen in the Cl-2/N-2 plasma and the InP substrate. The success of this technique appears to be based on a new InP dry etching concept which controls the volatility of PClx (x=1-5) products, thus balancing the desorption rate of InClx (x=1-3) products, in contrast to the conventional reactive ion etching method which enhances the desorption of nonvolatile InClx products by high-energy ion bombardment, (C) 1995 American Institute of Physics.