PURPOSE: Not to heat a glass substrate too much, to reduce an amount of diffusion of sodium, etc., and to prevent worm holes or pinholes, by baking an electron beam resist with microwave heating.

CONSTITUTION: A film of a heat-crosslinking type electron beam resist, such as a polymer or copolymer produced by using as monomers one or more compounds selected from a group consisting of acrylic acid, methacrylic acid, acrilonitrile, or their derivatives is formed on a chromium blank layer formed on a glass substrate containing ≥0.5% sodium and potassium. At that time, it is formed so as not to expose the chromium film, and this resist film is baked by heating it with microwaves. The temperature of the organic resist is raised to ≥160°C, but that of the glass substrate is not raised so much.