Image sensor and forming method therefor

Abstract

The invention provides an image sensor and a forming method therefor. The method comprising the steps that a substrate is provided, wherein the substrate comprises a plurality of pixel areas and a plurality of isolation areas, the isolation area is adjacent to the pixel area and surrounds the pixel area, the substrate comprises a semiconductor substrate, and the semiconductor substrate is providedwith a first surface and a second surface opposite to each other, a photosensitive structure is arranged in the semiconductor substrate of the pixel region, and a light sensing structure is exposed on the first surface of the semiconductor substrate; the second surface of the semiconductor substrate is exposed out of the surface of the blocking structure, and each blocking structure comprises a second type light blocking layer and a first type light blocking layer located on the two sides of the second type light blocking layer respectively, the second light blocking layer is located on the surface of the side wall of the first light blocking layer, the refractive index of the second light blocking layer is different from that of the first light blocking layer, and the refractive index ofthe first light-blocking layer is smaller than that of the semiconductor substrate. According to the method, the performance of the image sensor is improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to an image sensor and a forming method thereof. Background technique [0002] An image sensor is a semiconductor device that converts light signals into electrical signals. Image sensors are classified into complementary metal oxide (CMOS) image sensors and charge coupled device (CCD) image sensors. CMOS image sensor has the advantages of simple process, easy integration of other devices, small size, light weight, low power consumption and low cost. Therefore, with the development of image sensing technology, CMOS image sensors are increasingly used in various electronic products instead of CCD image sensors. At present, CMOS image sensors have been widely used in still digital cameras, digital video cameras, medical imaging devices, and automotive imaging devices. [0003] CMOS image sensors include front illuminated (FSI) image sensors and back illuminated (BSI) imag...

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Problems solved by technology

[0004] However, with the improvement of device integration, the density of pixel units in image sensors increases, and the crosstalk and dark current between adjacent pixel units continue to increase, which affects the performance of image sensors.

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