Multifunctional image sensor and manufacturing method thereof

Abstract

The invention relates to the field of image sensors and discloses a multifunctional image sensor and a manufacturing method thereof. According to the invention, a novel doping region is additionally arranged on the basis of the traditional CMOS image sensor and forms a light emitting diode structure together with a doping region on the surface of a light sensitive device so that the CMOS image sensor has both light sensitive and light emitting functions. A gate of a transfer transistor is formed on a substrate so that the integration level of the image sensor can be further improved. A second region is a p type semiconductor capable of improving the light sensitivity and eliminating dark current caused by surface state and surface defect so that the thermal noise is reduced. A PN structure between the second region and a first region forms the light sensitive device of the image sensor and the doping concentration of the second region is far larger than that of the first region so that thicker depletion layer and better light absorption can be obtained. The driving frequency of at least 24 Hz accords with the visual persistence time of human body so that continuous images without stagnation sense can be generated.

Description

Technical field [0001] The invention relates to the field of image sensors, in particular to a multifunctional image sensor. Background technique [0002] As we all know, an image sensor is a semiconductor device that can convert optical images into electrical signals. Image sensors can be roughly divided into Charge-Coupled Device (“CCD” for short) and Complementary Metal Oxide Semiconductor (“CMOS” for short) image sensors. [0003] The existing CMOS image sensor is composed of a CMOS digital-analog circuit and photosensitive pixels (ie, photosensitive basic units), and each photosensitive pixel includes a readout circuit area and an optical photosensitive area. [0004] According to its readout method, the existing CMOS image sensors can be roughly divided into passive pixel sensors (Passive Pixel Sensor, "PPS"), Active Pixel Sensors (Active Pixel Sensor, "APS") and digital pixels. There are three types of sensors (Digital Pixel Sensor, "DPS" for short). [0005] According to the...

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Problems solved by technology

[0012] However, the inventors of the present invention have found that the existing 3T or 4T type image sensors can only sense light, but cannot emit light, and their functions are relatively single.

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