Importance

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Abstract

An image sensor having improved antiblooming characteristics includes a plurality of photodetectors in a substrate at a surface thereof and arranged in an array of columns and rows. A CCD shift register extends along each column of the photodetectors. A separate overflow drain is adjacent each photodetector and an overflow barrier extends between each photodetector and its adjacent drain. Each photodetector has an active region of one conductivity type which is divided into first and second portions. The first portion of the active region has a higher concentration of the impurities of the one conductivity type than the second portion so as to have a lower potential during operation thereof. Thus, the charge carriers generated in the first portion will flow into the second portion where they are stored. This reduces the capacitance of the photodetector to increase it antiblooming characteristics while maintaining the sensitivity of the photodetector.

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First Claim