High-rate ion etching of GaAs and Si at low ion energy by using an electron beam excited plasma system

Abstract

By using a newly developed electron beam excited plasma (EBEP) system, etching characteristics of GaAs and Si in an ion energy range of 5 to 100 eV were investigated. Anisotropic etching profiles with high aspect ratios were obtained by both Ar ion beam etching (IBE) and Cl2 reactive ion beam etching (RIBE). Etching rates of 1.2 μm/min for GaAs and 0.5 μm/min for Si were demonstrated for the first time by Cl2 RIBE at ultralow ion acceleration voltage of 5 V. Selective ratios of etching rates for Si/SiO2 and GaAs/SiO2 are ∼33 and 80, respectively. Electrical and optical measurements on the etched samples indicated that damage degree introduced by the low-energy ions is negligible. Therefore, the EBEP system cannot only provide high etching rate because of its high ion current but also realize damageless ion etching due to its low ion energy.