PURPOSE: To enable to suppress the irregularity of charge voltage conversion gain at every element by implanting an impurity to a floating diffused region with a field oxide film, a mask material and the electrode of a gate region at a semiconductor substrate, thereby suppressing the variation in the etching amount of the field oxide film.
CONSTITUTION: After a field oxide film 31 is formed at the prescribed portion on a P-type silicon substrate 1, a gate oxide film 22 is formed, and an output gate 7 for forming a gate region and a transfer electrode 8 are formed on the film 22. Then, a mask material 33 having a hole 32 is formed near a floating diffused region forming portion partly inside of the film 31. Then, with the resist pattern 33, the film 31 and the output gate 7 as masks N-type impurity ions are implanted to the substrate to form a floating diffused region 34, the pattern 33 is separated, a charge transfer device is formed. Thus, the variation in the etching amount of the field oxide film is suppressed to suppress the irregularity in the charge voltage conversion gain at every element.