Complementary metal oxide semiconductor image sensor and manufacturing method thereof

Abstract

The invention discloses a complementary metal oxide semiconductor image sensor, comprising an optical filter, a photosensitive operating circuit unit, a silicon substrate, a microlens array, a metal interconnection dielectric layer, a metal interconnection layer, and a silicon substrate epitaxial layer. The corresponding silicon substrate epitaxial layer below each microlens of the microlens array, and the photosensitive operating circuit unit corresponding to a silicon substrate epitaxial layer region are a pixel unit. The sensor also comprises a silicon substrate reflective surface patch array on the bottom surface of the silicon substrate. The curved surface layer of the silicon substrate reflective surface patch array is provided with a reflecting medium layer. An interpixel potential isolating barrier is arranged between two adjacent pixel units. Each interpixel potential isolating barrier extends downwards and passes through the silicon substrate. The sensor can improve photoelectric conversion quantum efficiency, reduces signal crosstalk of carriers, and improves imaging quality of the image sensor under dark field environment.

Description

technical field [0001] The invention belongs to the technical field of semiconductor solid-state imaging devices, and in particular relates to a complementary metal oxide semiconductor image sensor and a manufacturing method thereof. technical background [0002] Complementary metal oxide image sensors are easy to integrate on-chip systems because their manufacturing processes are compatible with signal processing chips and other manufacturing processes. Noise ratio, so it has an advantage in the field of image sensor applications. [0003] An important feature index of an image sensor is light sensitivity, especially in low-light application environments, which plays a key role in image quality. Existing image sensors such as figure 1 As shown, it includes an optical filter 2, a photosensitive working circuit unit 4, a silicon substrate 6, a microlens array 1 arranged on the top surface of the optical filter 2, a metal interconnection medium layer 3 arranged on the bottom...

AI Technical Summary

Problems solved by technology

However, the depletion depth of silicon substrates in this way is still limited

Moreover, because of the large absorption depth of long-wavelength light, the carriers generated deep in the substrate easily exceed the control area of ​​the drift electric field and diffuse laterally into adjacent pixels, resulting in signal crosstalk.

In addition, if the isolation barrier between adjacent pixels is not deep enough for the deep region of the substrate, it will not be able to prevent the lateral diffusion of photogenerated carriers, and signal crosstalk will easily occur.

The signal crosstalk caused by this lateral diffusion will adversely affect the imaging resolution and color noise in low light

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