Multispectral imaging chip structure with wide free spectral range

By integrally depositing multiple spectral structures on the CMOS pixel photosensitive unit and employing a variable cavity FP filter and a cutoff filter film, the problems of difficulty in identifying targets with similar spectral information in RGB color images and material limitations are solved, realizing a multispectral imaging chip with a wide free spectral range, which has the advantages of high extinction ratio and low cost.

CN115993185BActive Publication Date: 2026-06-16TIANJIN JINHANG INST OF TECH PHYSICS
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
TIANJIN JINHANG INST OF TECH PHYSICS
Filing Date
2021-10-18
Publication Date
2026-06-16

AI Technical Summary

Technical Problem

In existing technologies, the photosensitive three-spectral range of RGB color images is too wide, making it impossible to identify and distinguish targets with similar spectral information. Furthermore, semiconductor materials compatible with CMOS technology limit the free spectral range, failing to meet the coverage of the visible spectrum. Light leakage in the external spectral range affects imaging performance.

Method used

Multiple beam-splitting structures are integrally deposited on the same pixel photosensitive unit. A line-scan FP filter structure is adopted. Through the design of a graded cavity structure, Bragg mirrors of different materials (such as SiO2/Si3N4 and α-Si/SiO2) are stacked to cover different spectral ranges. A cutoff filter film is deposited on the beam-splitting unit to achieve narrowband filtering of 490-1000nm.

Benefits of technology

It breaks through the limitations of material refractive index difference, broadens the free spectral range of monolithic image sensors, achieves narrowband spectral characteristics with high extinction ratio, and does not require changes to the readout circuit and FPGA system. It has advantages in size and cost, realizing a true single-chip SoC.

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Abstract

The application provides a wide free spectral range multispectral imaging chip structure, which comprises a pixel photosensitive unit and a light splitting unit, the pixel photosensitive unit is divided into a plurality of pixel regions along one of pixel directions a in sequence, and the other pixel direction b is not distinguished; the light splitting unit comprises a plurality of light splitting structures, the plurality of light splitting structures are integrally deposited and grown on the plurality of pixel regions one by one respectively, the light splitting structures are used for realizing narrowband filtering, and the plurality of light splitting structures respectively cover different spectral ranges. The application scheme breaks through the limitation of the free spectral range due to the material refractive index difference, and widens the free spectral range of narrowband filtering of a monolithic image sensor.
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