A stacked deep depletion image sensor pixel unit structure and fabrication method

Abstract

The invention discloses a stacked deep depletion image sensor pixel unit structure, comprising a first silicon chip with a P well and a second silicon chip with a clamping photodiode, and a first silicon chip with a first The back-end dielectric layer, the first back-end dielectric layer is provided with a first metal interconnection layer, the second silicon wafer is provided with a second back-end dielectric layer, and part of the pixel unit area on the back of the second silicon wafer is provided with P ++ Inject the substrate, the first silicon chip and the second silicon chip are stacked together through the bonding of the first and second subsequent dielectric layers, the upper end of the conductive through-silicon hole is electrically connected to the first metal interconnection layer, and the lower end passes through Conduct electrical extraction through the first dielectric layer, the second dielectric layer and the second silicon chip, which can effectively prevent the P well and P ++ The problem that leakage channels may be formed when different potentials are applied between implanted substrates improves the performance of the image sensor. The invention also discloses a method for manufacturing the pixel unit structure of the stacked deep depletion image sensor.

Description

technical field [0001] The present invention relates to the technical field of solid-state image sensors, and more particularly, to a stacked deep depletion image sensor pixel unit structure and a manufacturing method. Background technique [0002] An image sensor refers to a device that converts optical signals into electrical signals. Generally, large-scale commercial image sensor chips include charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensor chips. [0003] The absorption coefficient of silicon material to incident light decreases with the increase of wavelength. A pixel unit of a conventional CMOS image sensor usually uses filter layers of three primary colors of red, green and blue. The blue light has a wavelength of 450 nanometers, the green light has a wavelength of 550 nanometers, and the red light has a wavelength of 650 nanometers. Therefore, red light absorbs the deepest and blue light the shallowest. Blue light is abs...

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Problems solved by technology

However, the defect of this DDE is that its potential is affected by the potential of the photodiode, and the process window for injecting energy and dose is very small, so it is still easy to form a leakage path during the working process of the pixel, causing the performance of the image sensor to deteriorate

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