Solid-state image sensor and camera having impurity diffusion region

Abstract

A solid-state image sensor including a plurality of pixels formed on a semiconductor substrate, each pixel comprising a photoelectric conversion element including a charge accumulation region of a first conductivity type, a floating diffusion of the first conductivity type, and a transfer transistor which transfers charge in the charge accumulation region to the floating diffusion, comprises an element isolation region made of an insulator and arranged to isolate adjacent pixels from each other, and an impurity diffusion region of a second conductivity type arranged inside the semiconductor substrate to isolate adjacent pixels from each other, wherein a peak position of an impurity concentration of the impurity diffusion region of one pixel is disposed within a width of the floating diffusion, of the one pixel, along a straight line passing through the photoelectric conversion element, a gate electrode of the transfer transistor, and the floating diffusion which are of the one pixel.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a solid-state image sensor having a plurality of pixels and a camera including the sensor.[0003]2. Description of the Related Art[0004]In a solid-state image sensor having a plurality of pixels, part of the charge generated in a given pixel by photoelectric conversion sometimes mixes in an adjacent pixel. This may affect a signal from the adjacent pixel. Many color solid-state image sensors, in particular, use a Bayer arrangement as a pixel arrangement. In a Bayer arrangement, adjacent pixels output signals with different colors. In color solid-state image sensors, the phenomenon in which charge leaks out to adjacent pixels is called mixture of colors. There is known a structure in which, in order to reduce the mixture of colors, an impurity region serving as a potential barrier for signal charge is formed under an element isolation region located at the boundary between adjacent pixels ...

AI Technical Summary

Benefits of technology

[0007]The present invention provides a solid-state image sensor having a structure advantageous in decreasing the width of an element isolation region.

Problems solved by technology

With a decrease in the width of an element isolation region, the width of an impurity region forming a potential barrier under the element isolation region decreases, resulting in a degradation in preventive effect for mixture of colors.

Increasing the width of an impurity region to more than that of an element isolation region in order to form a sufficient potential barrier will suppress the depletion layer of a photodiode adjacent to the element isolation region and decrease the effective area.

This leads to a decrease in saturated output.

This leads to a decrease in effective area.