surface 45 of the etching electrode 40 as described above without having to use the spacer blocks 34 employed in the first representative embodiment the spacer blocks 34 are not required in this second representative embodiment because the grooves 46 in the major surface 45 provide conduits for the rapid removal of etching gas from the spaces between the etching electrode the reticle membrane and the reticle struts the masked reticle blank 1 mounted to the etching electrode 40 as described above is placed in the chamber of a dry etching apparatus etching gas is discharged into the chamber while the etching electrode is electrically energized which generates a plasma in the chamber the plasma ionizes molecules of the etching gas and the ions collide substantially perpendicularly with the first major surface 6 of the reticle blank the resulting collision of the ions with unmasked regions of the membrane etches the unmasked regions into the thickness dimension of the membrane dry etching is continued until the pattern defining apertures have been etched through the thickness dimension of the membrane thereby forming a stencil reticle for use in electron beam microlithography after the apertures have been completely etched depthwise through the thickness dimension of the membrane etching gas can penetrate through the apertures to the u201c back u201d of the reticle membrane however rather than remaining trapped behind the membrane the etching gas is exhausted readily through the grooves 46 defined in the etching electrode 40 this rapid exhaustion of etching gas prevents erosion of the back of the membrane and thus prevents membrane fracture dry etching of a reticle blank 50 fig3 according to this embodiment is performed using a conventional etching electrode however.