Process for etching a metal layer suitable for use in photomask fabrication

A method for etching a chromium-based layer, comprising:

• positioning an optically transparent silicon-based substrate having a chromium-based layer on a support member in a processing chamber, wherein the chromium-based layer has a patterned resist material deposited thereon and exposing a portion of the chromium-based layer;
• forming a plasma from a processing gas comprising chlorine gas, oxygen gas, and hydrogen bromide, with a molar ratio of chlorine gas to hydrogen bromide gas between about 10:1 and about 0.5:1 by applying power to a coil and bias to a substrate support in the processing chamber;
• and
• etching exposed portions of the chromium-based layer at a removal rate ratio of chromium-based layer to resist material of about 1:1 or greater.

A method for processing a chromium layer, comprising:

• positioning a reticle on a support member in a processing chamber, wherein the reticle comprises a chromium-based photomask layer formed on an optically transparent silicon-based material, the chromium-based photomask layer having a patterned resist material deposited thereon and exposing a portion of the chromium-based photomask layer;
• introducing a processing gas comprising chlorine gas, oxygen gas, and hydrogen bromide, with a molar ratio of chlorine gas to hydrogen bromide gas between about 10:1 and about 0.5:1;
• maintaining a chamber pressure between about 3 milliTorr and about 8 milliTorr;
• delivering a source power of about 400 watts to a coil disposed in the processing chamber to generate a plasma;
• supplying a bias power to the support member of about 20 watts;
• and
• etching exposed portions of the chromium-based photomask layer.