Method of manufacturing a semiconductor device

A method of manufacturing a solid-state image sensor that includes a semiconductor substrate, the method comprising:

• exposing a photoresist coated on a film made of an inorganic material using a photomask including a plurality of regions having different light transmittances;
• developing the photoresist to form a resist pattern including a plurality of regions having different thicknesses that depend on an exposure amount of the photoresist;
• performing etching using the resist pattern as a mask to form an inorganic material pattern from the inorganic material film, the inorganic material pattern including a plurality of regions having different thicknesses;
• and
• implanting impurity ions into the semiconductor substrate through the plurality of regions of the inorganic material pattern having different thicknesses to form a plurality of impurity regions whose depths from a surface of the semiconductor substrate to peak positions are different from each other, the plurality of the impurity regions including a first impurity region for forming a photoelectric conversion element, a second impurity region for forming a transistor, and a third impurity region for isolating the photoelectric conversion element and the transistor,
• wherein the depths to the peak positions depend on the thickness of the inorganic material pattern through which the implanted impurity ions pass.