Meta-Structure Image Sensor Pixels Without Color Filters
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Solution Overview
Problem
Current image sensors face limitations in miniaturization due to low light utilization efficiency and difficulty in reducing thickness with microlenses, color filters, and antireflection films, which hinders the achievement of high resolution and high sensitivity.
Innovation Solution
The development of image sensors utilizing a meta structure with a plurality of unit pixels, each comprising PIN photodiodes of different widths and spacer layers, where the absorption spectra of these photodiodes are expressed as independent linear combinations of color matching functions, allowing for efficient light absorption and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional color filters and microlenses are used in image sensors, then light utilization efficiency is limited and thickness reduction is difficult, but this maintains conventional structural simplicity
Solution Approach 1:
The patent changes the physical parameters of the photodiodes by creating multiple types with different widths (first width, second width, third width) and different absorption spectra. This allows the sensor to capture different wavelengths of light efficiently without requiring traditional color filters, thereby improving light utilization efficiency while maintaining a relatively simple structure.
Solution Approach 2:
The image sensor is segmented into multiple types of photodiodes (first PIN photodiode, second PIN photodiode, third PIN photodiode) with different widths and absorption characteristics within each pixel unit. This segmentation enables different regions to specialize in detecting different wavelengths, improving overall light utilization without adding complex external filtering layers.
2Reliability
If microlenses, color filters, and antireflection films are used, then image sensor performance is maintained, but thickness cannot be reduced to several micrometers or less
Solution Approach 1:
The patent extracts and removes the traditional microlens, color filter, and antireflection film layers from the image sensor structure. Instead, it uses internally integrated photodiodes with different widths and absorption spectra to perform the functions of light focusing and wavelength discrimination, enabling thickness reduction to several micrometers or less while maintaining performance.
Solution Approach 2:
The patent transitions from a vertical stacking approach (multiple layers stacked on top of each other) to a lateral differentiation approach (multiple photodiode types arranged side by side or in overlapping regions). This dimensional change eliminates the need for thick filtering layers while maintaining spectral discrimination capability.
3Productivity
If multiple photodiodes with different widths are used to improve light absorption, then manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating photodiodes with specifically designed different widths (first width, second width, third width) at different locations or regions within the pixel array. Each region is optimized for its specific function, and the manufacturing process is tailored to achieve the required precision for each local structure, balancing overall light absorption efficiency with feasible manufacturing precision requirements.
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 approach enables the creation of high-resolution, high-sensitivity image sensors with improved light absorption across various wavelengths, facilitating miniaturization beyond the limitations of traditional technologies, and achieving high color reproducibility similar to human vision.
Implementation Method 1
each of the unit pixels includes a first PIN photodiode having a first width, a second PIN photodiode having a second width different from the first width, and a third PIN photodiode having a third width different from the first width and the second width, and wherein the absorption spectra of the first to third PIN photodiodes are expressed as different independent linear combinations of functions obtained by dividing each of three color matching functions by wavelength
Data Source
AI summary
An image sensor pixel includes first, second and third PIN photodiodes having respective first, second and third widths, which are unequal to each other, and respective first, second and third absorption spectra associated therewith, which are unequal to each other. The first absorption spectra is a first linear combination of three color matching functions divided by a wavelength of light incident the image sensor, the second absorption spectra is a second linear combination of the three color matching functions divided by a wavelength of light incident the image sensor, and the third absorption spectra is a third linear combination of the three color matching functions divided by a wavelength of light incident the image sensor.