Investigation of the Effect of Atomic Composition on the Plasma-Chemical Etching Rate of Silicon Nitride in High-Power Transistors Based on an AlGaN/GaN Heterojunction

The effect of atomic composition on the rate of the plasma-chemical etching of silicon nitride in high-power transistors based on an AlGaN/GaN heterojunction is studied. It is shown how the subsequent process of its plasma-chemical etching depends on the configuration of the incorporation of hydrogen impurity atoms into the molecular structure of silicon nitride deposited in the plasma. The dependence of the etching rate on the process parameters (the working pressure in the chamber, the plasma-generator power, the working-gas flows, and the deposition temperature) is investigated. It is shown that the etching rate of the H x Si r N z H y film is independent directly on the hydrogen content but significantly depends on the ratio of [Si–H]/[N–H] bonds. The etching rate of H x Si r N z H y in high-density plasma at low powers is much less dependent on the configuration of hydrogen bonds than the etching rate of this dielectric in a buffer etchant.