| 摘要 |
A high-concentration light-receiving N-layer 32 is formed by ion implantation in a region near a substrate surface, and a low-concentration N-type epitaxial layer 25 is formed by epitaxial growth in a deeper region. The depletion layer of a photodiode is thus expanded to a deep portion of the substrate by the low-concentration N-type region 25, by which a photoelectric conversion effect on incident light of a long wavelength is increased to improve sensitivity. In the above stage, a deepest potential portion is formed on the substrate surface side. Therefore, a depletion voltage can be prevented from rising. Further, an intermediate-concentration N-type epitaxial layer 23 and a high-concentration N-type epitaxial layer 22 are formed in a stack of two layers by epitaxial growth in a region deeper than a region in which a first P-type layer 24, or a barrier region is formed, by which a shutter voltage can be prevented from rising. Thus, sensitivity is improved without causing a rise in the depletion voltage and shutter voltage.
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