Low damage etching by Inductively Coupled Plasma Reactive Ion Etch (ICP-RIE) and Atomic Layer Etching (ALE) of III-V materials to enable next generation device performance

Performance demands for many devices has driven feature dimensions to reduce to sub nm scale. Whilst new, and complex combinations of materials have increased the importance of interface effects at the atomic scale. Many of the macro-market dynamics such as Internet of Everything, increased volume in data traffic and energy efficiency require III-V based devices eg GaN, SiC. The combination of new materials and dimensions means that new etch solutions are required to achieve the accuracy and low damage needed for optimized device results. Low damage etching of AlGaN, GaN and SiN layers were studied using the PlasmaPro100 Cobra300 system from Oxford Instruments Plasma Technology, configured with ICP-RIE, RIE and ALE plasma etching modes. These techniques were used to etch shallow depths of between 5 and 100 nm in both SiN, AlGaN and GaN substrates and the resultant etched surface layer quality was measured using Atomic Force Microscopsy (AFM). ALE of SiN and GaN showed etch rates of 2.5 nm/min and 2 nm/min respectively. Using a conventional ICP-RIE process a GaN etch rate of 50 nm/min with a selectivity to AlGaN of 25:1 was achieved.