A new, crosslinking positive resist for deep‐uv photolithography has been developed. This resist, a copolymer of glycidyl methacrylate and methyl methacrylate (GCM), degrades on irradiation with light from a D2 lamp and has a sensitivity of 0.25 J/cm2. Three‐fourths μm line and space patterns are well resolved. It crosslinks at temperatures above 170°C in an inert atmosphere. This enables strengthening of the resist film by heat treatment after pattern delineation,greatly improving the adhesion and thermal properties of the resist. With these improvements, this resist can successfully be used for etching both SiO2 and phosphosilicate glass in a buffered HF solution. It can also be used for dry etching in CF4 plasma. It is preferable to use noncrosslinked GCM for CF4 plasma etching because the etching rate of noncrosslinked GCM is reduced to about one‐third that of crosslinked GCM.