PURPOSE: To enable a thin film pattern in mesa type section to be formed by a method wherein a step difference shaped resist pattern is used for dry etching process.

CONSTITUTION: An aluminium evaporation film 2 is formed on a silicon substrate 1 while the first resist layer 4 and the second resist layer 5 are laminated. Next, the second resist layer 5 is shaped into a mesa type section by pattern- formation using collective exposure while the first resist layer 4 is shaped into a wide pattern with both sides thereof jutted out forming into step difference parts 6. finally, the aluminium evaporation film 2 is formed after the wide pattern of the first resist layer 4 by dryetching process then the first resist layer 4 is formed after the shape of the second sesist layer 5 into the mase type section and then the aluminium evaporation film 2 is also formed into the mesa type sectional pattern by further dryetching process.