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 plasma chemical etching of silicon nitride in 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 the silicon nitride deposited in the plasma. The dependence of the etching rate on the parameters of the process (the working pressure in the chamber, the power of the plasma generator, the flow of working gases, the deposition temperature) is investigated. It was shown that the etching rate of the H$_{x}$Si$_{r}$N$_{z}$H$_{y}$ film does not depend 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 a 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.