| 摘要 |
The surface of a semiconductor wafer comprises a silicon substrate and a well positioned in a predetermined area just under the surface of the substrate. A photo diode comprises a MOS transistor positioned on the surface of the well, a photo sensor positioned beside the well and electrically connected to the MOS transistor, and an insulation layer positioned on the surface of the substrate surrounding the photo sensor. The photo sensor comprises a first doped region positioned on the surface of the photo sensor, and a second doped region positioned between the first doped region and the insulation layer, a portion of the second doped region at least partially under the insulation layer. The dopant density of the second doped region is less than that of the first doped region, and the second doped region functions to reduce the electrical field around the first doped region so as to reduce the leakage current.
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