Pixel unit of CMOS image sensor

Abstract

The invention discloses a pixel unit of a CMOS image sensor and a manufacturing method of the pixel unit and belongs to the technical field of semiconductors. The pixel unit comprises a photosensitive diode and a pass transistor set. The pass transistor set comprises a plurality of pass transistors which are connected at the source electrode end and the drain electrode end in parallel respectively. The grid electrode of each pass transistor and an injection area of the photosensitive diode form an overlapping are, wherein the overlapping areas are different in size, so that different transmission efficiencies are achieved. The photosensitive diode is used for conducting photovoltaic conversion so that a photon can be converted into an electron. The pass transistor set is used for achieving the purpose that the pass transistor corresponding to the transmission efficiency is selectively started according to the illuminance of incident light, so that electron transmission is conducted, and therefore the electron is transmitted to the drain electrode end from the source electrode of the pass transistor set and converted into a voltage signal. According to the pixel unit of the CMOS image sensor, the pass transistor, corresponding to the transmission efficiency, of the pass transistor set is selectively started according to the illuminance of incident light, so that electron transmission is conducted, and therefore the index of high sensitivity and the index of high dynamic are achieved.

Description

technical field [0001] The invention belongs to the field of integrated circuits, and in particular relates to a pixel unit of a CMOS image sensor. Background technique [0002] An image sensor refers to a device that converts optical signals into electrical signals. Image sensors include charge-coupled devices (Charge-coupled Device, hereinafter referred to as CCD image sensors) and complementary metal oxide semiconductor image sensors (CMOS IMAGE SENSOR, hereinafter referred to as CIS image sensors). [0003] Compared with CCD image sensors, CMOS image sensors have the characteristics of low power consumption, low cost, and compatibility with CMOS technology, so they are more and more widely used. CMOS image sensors are not only used in consumer electronics, such as miniature digital cameras (DSC), mobile phone cameras, video cameras, and digital single-lens reflex cameras (DSLR), but also in automotive electronics, video surveillance, biotechnology, and medicine. [000...

AI Technical Summary

Problems solved by technology

However, the pixel unit in the prior art can only meet one of the indicators of high sensitivity and high dynamic range, but cannot simultaneously achieve the two indicators of high sensitivity and high dynamic range

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