PURPOSE: To rationalize processes and prevent disconnection of bonding wire by forming the polyimide resin film for shielding α rays using photosensitive polyimide resin.

CONSTITUTION: Photosensitive polyimide resin shows the difference in solubility to a specific solvent between a beam radiated part and no-radiated part when the photosensitive group is introduced into the polyimide resin or the precursor and the light beam (usually, ultra-violet ray) is irradiated to such resin. Therefore, the solution of precursor of the photosensitive polyimide is coated on the slicon water forming the memory circuit and it is dried during an hour at the temperature 80°C. Thereafter, the ultraviolet ray is irradiated to said wafer using a photomask so that the light beam is not irradiated to the area on which it is necessary to form an α ray shielding film. The light irradiated part is developed by a developer and the film on the area where it is not required to form the α ray shielding film is removed. Next, the α ray shielding film is formed on a bonding pad by thermal processing. A chip is cut out from a silicon wafer and it is bonded to a lead frame and then connected with bonding wire, and then sealed.