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.
The etching characteristics of ZnO epitaxial layers in Oxford Plasmalab 100 ICP 180 and 380 systems are
investigated. Etch rates are studied as a function of gas composition, ICP power and RF bias power. Surface
profilometry and scanning electron microscopy are used to characterize etch rates and surface morphologies. Highlights
from other recently published results are also discussed.
New processes using HBr chemistry have been developed for etching InP and related materials using photoresist as a
mask in a high ion density inductively coupled plasma system. An etch rate of above 1 micron/min, a selectivity of 14:1
with vertical profile, and smooth etched surface have been achieved. The effects of ICP power, table temperature,
chamber pressure and DC bias on etching rate, selectivity, etched profile and surface morphology will be discussed in