Method for etching a quartz layer in a photoresistless semiconductor mask

摘要

A chromeless phase lithography mask ( 30 ) that does not require photoresist to manufacture has a quartz substrate ( 32 ) is etched by using a plasma ( 38 ) containing one of a nitrogen augmented hydro-fluorocarbon oxygen mixture and a nitrogen augmented fluorocarbon oxygen mixture. Various hydro-fluorocarbons or fluorocarbons may be used. The nitrogen addition results in etched openings in the quartz substrate that have substantially vertical sidewalls in a uniform manner across the substrate. Surface roughness is minimized and edges of the openings are well-defined with minimal rounding. The etch rate is rendered controllable by reducing bias power without degrading a desired vertical sidewall profile.