| 摘要 |
The surface of the semiconductor wafer includes a silicon substrate containing first-type dopants, a well of first-type dopants positioned in a predetermined region on the substrate, a photo diode positioned on the semiconductor wafer and comprising an active region positioned on the surface of the well, the active region being used to form a MOS transistor of second-type dopants, and an insulation layer positioned on the surface of the substrate surrounding a predetermined photo sensor, the photo sensor positioned beside the well. A first ion implantation process is performed to form a first doped region of second-type dopants on the surface of the photo sensor. A second ion implantation process is then performed to form a second doped region of second-type dopants inside the photo sensor. The second doped region is positioned under the first doped region, 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 leakage current.
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