Room-Temperature Inductively Coupled Plasma Etching of InP UsingCl2/N2 and Cl2/CH4/H2

Abstract

We optimize the room-temperature etching of InP usingCl2/CH4/H2 and Cl2/N2 inductivelycoupled plasma reactive ions. A design of experiment isused in the optimization. The results, in terms of etch rate, surfaceroughness and etched profile, are presented. These Cl2-basedrecipes do not require substrate heating and thus can be more costeffectively and widely applied. The Cl2/CH4/H2 process isable to give a higher etch rate (about 850 nm/min) andcleaner surface with less polymer formation compared to theconventional CH4/H2 process. The Cl2/N2process produces even higher etch rate (as high as 2 μm/min), butrougher surface with slight sidewall undercut. The Cl2/N2process also has no polymer formation due to the absence of methanegas. Both the processes give very good selectivity to the silicondioxide (SiO2) etch mask. The selectivity of InP to the oxidemask (up to 55:1) for the Cl2/N2 process is one of thehighest reported so far. The etched structures possess reasonably goodsidewall verticality and surface quality comparable to that obtainedunder elevated temperature condition (>200°C).