Isolation structure having a second impurity region with greater impurity doping concentration surrounds a first impurity region and method for forming the same, and image sensor including the isolation structure and method for fabricating the image sensor

An image sensor comprising:

• a substrate;
• a plurality of photoelectric conversion regions formed in the substrate, wherein each of the photoelectric conversion regions corresponds to a pixel of the image sensor;
• and
• an isolation structure formed in the substrate, between each of the plurality of photoelectric conversion regions, the isolation structure comprising:
• a first isolation structure formed in a trench in the substrate, and
• a second isolation structure formed adjacent to the first isolation structure, the second isolation structure including:
• a first impurity region formed in the substrate, the first impurity region having a first impurity doping concentration, and
• a second impurity region formed to surround the first impurity region, the second impurity region having a second impurity doping concentration that is greater than the first impurity doping concentration.

An image sensing device comprising:

• an active pixel sensor array suitable for outputting pixel signals corresponding to incident light;
• a row driver suitable for driving a readout operation by simultaneously activating all of pixels in one row of the active pixel sensor array;
• a pixel signal processor suitable for receiving the pixel signals output from the active pixel sensor array to output digital signals by sampling the pixel signals;
• and
• a controller suitable for controlling the row driver and the pixel signal processor to perform a process suitable for the pixel signals,
• wherein the active pixel sensor array includes:
• a substrate;
• a plurality of photoelectric conversion regions formed in the substrate, wherein each of the photoelectric conversion regions corresponds to a pixel of the active pixel sensor array;
• and
• an isolation structure formed in the substrate, between each of the plurality of photoelectric conversion regions, the isolation structure comprising:
• a first isolation structure formed in a trench in the substrate, and
• a second isolation structure formed adjacent to the first isolation structure, the second isolation structure including:
• a first impurity region formed in the substrate, the first impurity region having a first impurity doping concentration, and
• a second impurity region formed to surround the first impurity region, the second impurity region having a second impurity doping concentration that is greater than the first impurity doping concentration.