Abstract: A new anisotropic dry etching system using a hot jet tube to heat and dissociate non-reactive source gas to form a directed flux of reactive specie or radicals for etching materials through openings in a resist or a reusable stencil of SiN.sub.x wherein x is in the range of 1.5 to 0.5. Si and GaAs may be etched using Cl.sub.2, F.sub.3, Br.sub.2 or SF.sub.6 source gasses. Pb or Hg, Cd, Te may be etched using n-butane, dimethyl ether or acetone as a source gas for CH.sub.3 radicals. The tube may be formed of tungsten or where fluorine is used as a source gas, an irridium tube is preferred. Alternatively, a tube formed of rhenium or an alloy of rhenium and tungsten is preferred for some applications.