Method for manufacturing solid-state image sensor

A method for manufacturing a solid-state image sensor including, in a semiconductor substrate, a first pixel configured to receive a light in a first wavelength range, and a second pixel configured to receive a light in a second wavelength range, a central wavelength in the second wavelength range being shorter than a central wavelength in the first wavelength range,

• the first pixel including a first charge accumulation portion of a first conductivity type in a first region of the semiconductor substrate,
• the second pixel including a second charge accumulation portion of the first conductivity type in a second region of the semiconductor substrate, and a semiconductor region of a second conductivity type in a third region of the semiconductor substrate, the second conductivity type being different from the first conductivity type,
• the manufacturing method comprising the steps of:
• forming the first charge accumulation portion and the second charge accumulation portion;
• forming a buried layer of the second conductivity type of the semiconductor substrate at a position deeper than the first charge accumulation portion and the second charge accumulation portion;
• and
• forming the semiconductor region of the semiconductor substrate between the second region and the buried layer,
• wherein in the step of forming the first charge accumulation portion and the second charge accumulation portion, impurities are doped in the first region and the second region to make a net quantity of doping impurities of the first conductivity type in the second region be larger than a net quantity of doping impurities of the first conductivity type in the first region,
• wherein in the step of forming the semiconductor region, impurities of the second conductivity type are doped in the third region, and the impurities of the second conductivity type to reduce a difference between a net quantity of doping impurities of the first conductivity type in the first region and a net quantity of doping impurities of the first conductivity type in the second region.