Low ion energy ECR etching of InP using Cl_2/N_2 mixture

摘要

The low energy (about 30eV) ion etching of InP with excellent etching performances of vertical sidewall profile, smooth surface and high etching rate (more than 1000 A/min) has been realized by an ECR plasma using a Cl_2/N_2 mixture. Surface analysis by XPS and plasma diagnostics by OES suggest that the mechanism of this etching may be dominated by the two effects; the remarkable reduction of Cl neutral radical density by the reaction of Cl+N→NCl and the formation of InN and P_3N_5 due to the reaction between the atomic nitrogen in the Cl_2/N_2 plasma and the InP substrate. This technique appears to be based on a new concept for InP dry etching to control the volatilizing rate of PCl_x(x=1-5) products balancing to the desorption rate of InCl_x(x=1-3) products, in opposition to the conventional method enhancing the desorption of non-volatile InCl_x products comparably to that of volatile PCl_x products by high energy ion bombardment.