CMOS Image Sensor Layout With Absorption Structure for Cross-Talk
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Solution Overview
Problem
Complementary metal-oxide semiconductor (CMOS) image sensors experience cross-talk between laterally adjacent image sensor elements configured for different wavelengths, leading to a decreased signal-to-noise ratio (SNR) and degraded performance due to electromagnetic radiation reflection from conductive features.
Innovation Solution
An image sensor device with an interconnect structure and image sensor element layout that includes an absorption structure underlying the first image sensor element, made of conductive materials like titanium nitride, to prevent reflection of electromagnetic radiation within specific wavelengths, thereby reducing cross-talk between neighboring image sensor elements and increasing SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive features are used in the interconnect structure, then electrical connectivity is achieved, but electromagnetic radiation reflection occurs causing cross-talk between adjacent image sensor elements
Solution Approach 1:
An absorption structure made of conductive material is introduced as an intermediary component between adjacent image sensor elements. This absorption structure serves as a mediator that absorbs electromagnetic radiation before it can reflect off the interconnect structure and cause cross-talk, thereby resolving the contradiction between maintaining electrical connectivity and preventing harmful radiation reflection.
Solution Approach 2:
The patent converts the harmful effect of electromagnetic radiation reflection into a beneficial outcome by using the same conductive material properties that cause reflection to instead absorb the radiation. The absorption structure utilizes conductive material characteristics to dissipate electromagnetic energy, transforming the potential harm of reflection into the benefit of cross-talk reduction.
2Productivity
If image sensor elements are placed laterally adjacent to each other, then device integration density increases, but cross-talk between elements increases due to electromagnetic radiation reflection
Solution Approach 1:
The absorption structure acts as an intermediary barrier placed between laterally adjacent image sensor elements. It absorbs electromagnetic radiation that would otherwise travel between closely spaced elements, enabling high integration density while maintaining signal integrity and preventing cross-talk interference.
Solution Approach 2:
The absorption structure is selectively positioned in specific locations between adjacent image sensor elements where cross-talk is most problematic. This localized approach allows the patent to maintain high integration density overall while applying radiation absorption only where needed to protect signal-to-noise ratio in critical areas.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The absorption structure effectively decreases cross-talk between image sensor elements, enhancing the signal-to-noise ratio and overall performance of the image sensor device by impeding electromagnetic radiation reflection, thus improving the reliability and accuracy of image production.
Implementation Method 1
an absorption structure underlying the first image sensor element, made of conductive materials like titanium nitride, to prevent reflection of electromagnetic radiation within specific wavelengths
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an image sensor device including a first image sensor element and a second image sensor element disposed within a substrate. An interconnect structure is disposed along a front-side surface of the substrate and comprises a plurality of conductive wires, a plurality of conductive vias, and a first absorption structure. The first image sensor element is configured to generate electrical signals from electromagnetic radiation within a first range of wavelengths. The second image sensor element is configured to generate electrical signals from the electromagnetic radiation within a second range of wavelengths that is different than the first range of wavelengths. The second image sensor element is laterally adjacent to the first image sensor element. Further, the first image sensor element overlies the first absorption structure and is spaced laterally between opposing sidewalls of the first absorption structure.