CMOS image sensor and its forming method

Abstract

The invention discloses a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) image sensor and a forming method thereof. The CMOS image sensor comprises a semiconductor substrate, an epitaxial layer, a gate structure, a drain region, a lightly-doped region, a heavily-doped region, isolating layers, light-transmitting dielectric layers and shading layers, wherein the epitaxial layer is positioned on the surface of the semiconductor substrate; the gate structure is positioned on the surface of the epitaxial layer; the drain region is positioned in the epitaxial layer at one side of the gate structure; the lightly-doped region is positioned in the epitaxial layer at the other side of the gate structure; the heavily-doped region is positioned in the epitaxial layer between the lightly-doped region and the gate structure; the isolating layers are positioned on the surface of the lightly-doped region and the surface of the heavily-doped region; the light-transmitting dielectric layers are positioned on the surface of the epitaxial layer and the surface of the gate structure; and the shading layers are positioned on the surfaces of the light-transmitting dielectric layers. The barrier capacitance between the heavily-doped region and the epitaxial layer is greater than that in the prior art, so that the barrier capacitance between the heavily-doped region and the epitaxial layer can be used for accommodating more electronics, even if brighter light is incident to store enough electronics, and further, the high dynamic range of the CMOS image sensor is widened.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a high dynamic range CMOS image sensor and a forming method thereof. Background technique [0002] With the rapid development of digital technology, semiconductor manufacturing technology and network, digital products such as digital cameras, digital video cameras, etc. are playing more and more important roles in daily life. As a key component of digital cameras and video cameras, image sensor products have become the focus of the industry at present and in the future, attracting investment from many manufacturers, and technologies related to image sensors have also become research hotspots. [0003] The role of the image sensor is to convert an optical image into a corresponding electrical signal. Image sensors are classified into complementary metal oxide (CMOS) image sensors and charge coupled device (CCD) image sensors. The advantage of the CCD image sensor is that it has high...

AI Technical Summary

Problems solved by technology

However, the photosensitive areas of the image sensor used to collect low-brightness incident light and high-brightness incident light account for only half of the photosensitive area of ​​the entire pixel unit, and using the image sensor to collect incident light and generate images will result in a reduction in image resolution. And the image sensor is still unable to collect extremely bright incident light

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