Solids

Chromium mask for plasma-chemical etching of Al$_x$Ga$_{1-x}$N layers

D. Yu. Protasov^a, N. R. Vitsina^a, N. A. Valisheva^a, F. N. Dultsev^a, T. V. Malin^a, K. S. Zhuravlev<sup>ab

a</sup> Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk
^b Novosibirsk State University

Abstract: The influence of the mask material used for formation of GaN mesa-structures using plasma-chemical etching in a BCl$_3$ : Ar : N$_2$ atmosphere is studied. It is shown that a bilayer SiO$_2$/Cr mask in which the thickness of the chromium layer is six to seven times smaller than a desired etch depth provides effective protection of the surface and allows the formation of structures with a flat surface for an etch depth of up to 2.5 $\mu$m. When the mask is produced by conventional lithography, the slope of the side walls is no more than 10$^\circ$ and decreases when liftoff lithography is applied.

Received: 28.11.2013

 English version: Technical Physics, 2014, 59:9, 1356–1359

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