Plasma etching of GaN/AlGaN structures in a chlorine-containing medium Cl₂/Ar/O₂

Etching of GaN/AlGaN heterostructures on a Sentech SI-500 installation with an inductively coupled plasma source is considered. Etching was carried out in a chlorine-containing Cl₂/Ar gas mixture with the addition of various amounts of oxygen. The influence of various technological factors on the etching rate and etching selectivity between GaN and AlGaN layers: the amount of oxygen in the gas mixture, power source, inductively coupled plasma, high-frequency power. Etching modes have been established in which the selectivity of etching of GaN/AlGaN layers reaches 30:1. Based on the developed plasma etching technology, a route for manufacturing transistors based on heterostructures with conductive cap layers has been developed. It is shown that the characteristics are improved when using a conductive cap layer by reducing the contact resistance and channel resistance. The values of the current density of 380 mA/mm and the steepness of 143 mS/mm are obtained.

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