CMOS Image Sensor Light Routing for Oblique Incidence
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Solution Overview
Problem
The quantum efficiency and angular response of CMOS image sensors are compromised when external light is oblique to the metasurface or lens layer, leading to reduced performance.
Innovation Solution
Incorporating an enhancement layer with first pillars and a router layer featuring second pillars, each with specific refractive indices and dimensions, to provide additional transverse momentum for light guidance, enhancing quantum efficiency and angular response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metasurface layer or lens layer is formed to receive external light, then the image sensor can capture light, but the quantum efficiency and angular response deteriorate when external light is oblique with respect to the upper surface
Solution Approach 1:
The patent introduces transverse layers (first and second transverse layers) that extend in the transverse direction (x-direction) rather than only in the vertical direction. These transverse layers provide additional transverse momentum to oblique light, enabling the light to be guided to photodiodes even when incident at large angles. This dimensional extension resolves the contradiction by adding a new degree of freedom for light propagation.
Solution Approach 2:
The patent divides the light guidance function into multiple segmented components: enhancement layers with first transverse layers, chromatic dispersion layers, and router layers with second transverse layers. Each segment performs a specific function in the light guidance process, collectively enabling both high quantum efficiency and wide angular response through coordinated action of these segmented structures.
2Adaptability or versatility
If the critical dimension of second pillars is reduced to increase their number, then the angular response improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies the critical dimensions of pillars across different layers and positions. The first pillars in the enhancement layer have different dimensions than the second pillars in the router layer, and pillars at different lateral positions have different dimensions. This parameter optimization enables wide angular response while maintaining manufacturability by finding the optimal balance between pillar size and number.
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 solution effectively guides a larger portion of light to corresponding photodiodes, increasing the quantum efficiency and angular response of the image sensor.
Implementation Method 1
A first transverse layer in the enhancement layer and a second transverse layer in the router layer provide additional transverse momentum for a light, so that the light would be more easily guided to the corresponding photodiodes
Implementation Method 2
The chromatic dispersion layer is disposed on the enhancement layer
Data Source
AI summary
The image sensor includes a photoelectric conversion layer, a color filter layer, an enhancement layer, a chromatic dispersion layer, and a router layer. The photoelectric conversion layer includes a plurality of photodiodes and a plurality of deep trench isolations separating the photodiodes. The enhancement layer is disposed on the color filter layer, wherein the enhancement layer includes a plurality of first pillars, a filling, and a first transverse layer. The router layer is disposed on the chromatic dispersion layer, wherein the router layer includes a second transverse layer and a plurality of second pillars. A critical dimension of the second pillars is smaller than a critical dimension of the first pillars.