DRY ETCHING METHOD FOR PHOTOMASK

摘要

PURPOSE:To provide the etching method which makes it possible to obtain a photomask having high accuracy by using a dry etching device having rotating magnetic fields. CONSTITUTION:A photomask substrate 11 is mounted on an RF electrode 10 surface in an etching chamber 2 of the dry etching device 1 having the rotating magnetic fields by electromagnets 5 to 8 and a pattern material is etched by reactive ion etching under the conditions of 50 to 150 gauss magnetic field intensity of the electromagnets, 0.03 to 0.3Torr reactive gaseous pressure in the etching chamber and 0.20 to 0.32W/cm<2> RF electric power density of the electrodes. The controllability of plasma is good and selection ratios are improved. The pattern material of the photomask is subjected to the etching with small CD loss, good intra-surface uniformity and high accuracy by setting magnetic field intensity, reactive gaseous pressure and RF electric power density to the values described above.