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

We optimize the room-temperature etching of InP using Cl2/CH4/H2 and Cl2/N2 inductively coupled plasma reactive ions. A design of experiment is used in the optimization. The results, in terms of etch rate, surface roughness and etched profile, are presented. These Cl2-based recipes do not require substrate heating and thus can be more cost effectively and widely applied. The Cl2/CH4/H2 process is able to give a higher etch rate （about 850 nm/min） and cleaner surface with less polymer formation compared to the conventional CH4/H2 process. The Cl2/N2 process produces even higher etch rate （as high as 2μm/rain）, but rougher surface with slight sidewall undercut. The Cl2/N2 process also has no polymer formation due to the absence of methane gas. Both the processes give very good selectivity to the silicon dioxide （SiO2） etch mask. The selectivity of InP to the oxide mask （up to 55：1） for the Cl2/N2 process is one of the highest reported so far. The etched structures possess reasonably good sidewall verticality and surface quality comparable to that obtained under elevated temperature condition （〉 200℃）.