Pixels for cmos image sensors

Abstract

A unit pixel of a complementary metal-oxide semiconductor (CMOS) image sensor includes a photoelectric conversion element, a transfer transistor, a boosting capacitor and a signal transfer circuit, where the photoelectric conversion element generates a charge based on incident light, the transfer transistor transfers the charge to a floating diffusion node in response to a transfer control signal, the boosting capacitor is disposed between a gate of the transfer transistor and the floating diffusion node, the signal transfer circuit transfers an electric potential of the floating diffusion node in response to a selection signal, and a dynamic range of the electric potential of the floating diffusion node may be widened and a drain-source voltage difference of the transfer transistor may be increased so that the charge transfer efficiency may be enhanced.

Description

technical field [0001] The present invention relates to image sensors, and more particularly to complementary metal oxide semiconductor (CMOS) image sensors. Background technique [0002] An image sensor is a semiconductor module that converts photographic images into electrical signals. Image sensors are generally widely used in digital cameras, cellular phones with built-in cameras, visual systems, and the like. [0003] There are generally two types of image sensors on the market. One is a Charge Coupled Device (CCD) type image sensor, and the other is a Complementary Metal Oxide Semiconductor (CMOS) type image sensor. CMOS type image sensors have inferior noise characteristics and image quality compared to CCD type image sensors. However, the CCD type image sensor has disadvantages in production cost and power consumption compared with the CMOS type image sensor. The CMOS type image sensor may be manufactured through a conventional semiconductor manufacturing process...

AI Technical Summary

Problems solved by technology

However, the method is not easy to implement because it is difficult to form a floating diffusion junction (or a floating diffusion region) since the electrode of the transfer gate extends into the floating diffusion region.

[0014] That is, it is difficult to form the floating diffusion region using the gate self-aligning ion implantation technique

Therefore, when the transfer gate is formed after the floating diffusion region is formed, additional photomask processing is required, so the manufacturing process becomes more complicated and the manufacturing cost increases

In addition, since it is difficult to design and control the channel width of the transfer transistor, it is difficult to guarantee the electrical characteristics of the transfer transistor

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