Multilayer Stepped Pixel Lens for Image Sensor Light Condensing
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Solution Overview
Problem
Conventional image sensors face challenges in achieving improved light condensing efficiency and uniformity due to limitations in micro lens formation processes, which affect focal distance control and increase crosstalk, and are restricted by material limitations when forming hemispherical shapes over color filters.
Innovation Solution
The image sensor incorporates a pixel lens with a multilayer stepped structure, where a lower light condensing layer has a larger area than an upper layer, and a focusing layer with a higher refractive index than the pixel lens, allowing for effective light condensation and adjustable focal distance without curvature changes, combined with an anti-reflection structure for enhanced light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional micro lens formation process is used, then the lens can be formed over the color filter, but the light condensing efficiency is insufficient and crosstalk increases
Solution Approach 1:
The pixel lens is divided into multiple light condensing layers (first light condensing layer, second light condensing layer, etc.) with different widths, where each layer segments the light condensation function to improve efficiency and reduce crosstalk by directing light more precisely to the photoelectric conversion element
Solution Approach 2:
Different light condensing layers have different local properties (different widths), with the first light condensing layer having a larger width than the second light condensing layer, allowing each layer to perform light condensation at different stages and improve overall efficiency while reducing crosstalk
2Manufacturing precision
If the focal distance is adjusted by changing lens curvature, then the focal distance can be controlled, but the process complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of changing the curvature of the lens to control focal distance, the invention changes the width parameters of the light condensing layers (first light condensing layer wider than the second), providing a simpler manufacturing approach to achieve focal distance control
Solution Approach 2:
The conventional approach of controlling focal distance through curvature change is inverted by controlling it through width variation of light condensing layers, simplifying the manufacturing process while achieving the same functional result
3Ease of manufacture
If a hemispherical lens shape is formed, then the lens can be created over color filters, but material limitations restrict the formation process
Solution Approach 1:
The lens is segmented into multiple light condensing layers formed sequentially, which overcomes material limitations by allowing different materials to be deposited in layers, each performing specific light condensation functions without requiring a single complex hemispherical formation process
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
This configuration improves light condensing efficiency and quantum efficiency in unit pixels, leading to enhanced performance and integration capabilities of the image sensor, while allowing for precise focal distance adjustment within a limited space.
Implementation Method 1
a first pixel lens formed over the first photoelectric conversion element of the first pixel and comprising a first lower light condensing layer and a first upper light condensing layer
Implementation Method 2
a first color filter covering the first pixel lens and filtering a visible ray of a first wavelength band
Implementation Method 3
a focusing layer inserted between the first photoelectric conversion element and the first pixel lens and between the second photoelectric conversion element and the second pixel lens; The focusing layer may have a greater refractive index than the first and the second pixel lenses
Implementation Method 4
an anti-reflection structure formed over the first and the second color filters; The anti-reflection structure may include an anti-reflection layer or a hemispherical lens
Data Source
AI summary
Disclosed are an image sensor including a light collection member having a multi-layer step shape and an electronic device including the same. This technology can improve light condensing efficiency in a unit pixel since a corresponding pixel lens is included. Furthermore, light condensing efficiency in a unit pixel can be improved more effectively by controlling the width of a corresponding pixel lens so that the pixel lens corresponds to the wavelength of incident light whose color has been separated by a corresponding color filter. As described above, quantum efficiency in the photoelectric conversion element can also be improved since light condensing efficiency in a unit pixel is improved. As a result, performance of the image sensor can be improved.