A new co-polymer of glycidyl methacrylate and n -(2-hydroxy-3-cinnamoyloxy)-propyl methacrylate was designed as a negative Deep UV resist, in which a well-regulation of the photo-absorption intensity of the resist film is easily performed through the preparation. High sensitivity (100 time more sensitive than PMMA) and high resolution (up to 0.5 μm width line) are characteristics of the new resist. Resist patterns obtained are excellent as an etching mask in the SiO₂ etching by buffered HF solutions.