3D Stacked Image Sensor with Depth-Varied Photosensing Layers
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Solution Overview
Problem
Current image sensors face challenges in reducing size while maintaining sensitivity and improving color separation characteristics, leading to inefficiencies in light absorption and potential crosstalk between different wavelength spectra.
Innovation Solution
The image sensor employs a stacking structure with photoelectric devices and semiconductor substrates, featuring photo-sensing devices with different thicknesses and depths to selectively absorb and sense light across various wavelength spectra, along with color filters that transmit specific wavelengths, optimizing light absorption and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional planar image sensor structure is used, then the sensor can capture images, but the sensor size is large and sensitivity is limited
Solution Approach 1:
The patent transitions from a conventional planar (2D) sensor structure to a three-dimensional stacked structure. Multiple photoelectric conversion units are arranged vertically in different layers, each detecting different wavelength bands. This dimensional change allows the sensor to maintain high sensitivity through multiple detection layers while reducing the overall footprint area, thus resolving the contradiction between sensor size and sensitivity.
2Reliability
If multiple photo-sensing devices are stacked to improve sensitivity, then sensitivity improves, but crosstalk between different wavelength spectra increases
Solution Approach 1:
The patent applies local quality by assigning different spectral detection characteristics to different photoelectric conversion units in the stack. Each unit is optimized for specific wavelength bands (e.g., visible light, infrared), and color filters are selectively applied to specific layers. This localized optimization allows multiple units to operate simultaneously with minimal crosstalk, maintaining high sensitivity while preventing spectral interference.
Solution Approach 2:
The patent introduces color filters as intermediary elements between the light source and photoelectric conversion units. These filters selectively transmit specific wavelength bands while blocking others, acting as mediators that prevent crosstalk between adjacent detection layers. The filters enable each photoelectric unit to receive only its designated wavelength range, thus eliminating harmful spectral interference while maintaining the benefits of the stacked structure.
3Measurement precision
If photo-sensing devices with different thicknesses are used to improve color separation, then color separation characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by varying the thickness of photo-sensing devices and color filters across different layers to optimize color separation. Thinner layers are used for certain wavelength bands while thicker layers detect others, creating optimal optical paths for each spectral region. This parameter optimization achieves superior color separation characteristics while the systematic approach to varying thicknesses across standardized layers helps manage manufacturing complexity.
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 results in a highly sensitive image sensor with improved color separation characteristics and reduced light loss, enabling efficient light absorption and effective color differentiation.
Implementation Method 1
a photoelectric device configured to selectively absorb light associated with a first wavelength spectrum. The first wavelength spectrum may be associated with a first color of three primary colors
Implementation Method 2
The first photo-sensing device may be configured to sense light associated with a second wavelength spectrum. The second wavelength spectrum may be associated with a second color of the three primary colors
Implementation Method 3
The second photo-sensing device may be configured to sense light associated with a third wavelength spectrum. The third wavelength spectrum may be associated with a third color of the three primary colors
Implementation Method 4
The first color filter may be configured to selectively transmit light associated with the first wavelength spectrum and light associated with the second wavelength spectrum
Implementation Method 5
The second color filter may be configured to selectively transmit light associated with the third wavelength spectrum
Data Source
AI summary
An image sensor may include a photoelectric device configured to selectively absorb light associated with a first color of three primary colors, a semiconductor substrate that is stacked with the photoelectric device and includes first and second photo-sensing devices configured to sense light associated with second and third colors of three primary colors. The first and second photo-sensing devices may have different thicknesses, different depths from a surface of the semiconductor substrate, or different thicknesses and different depths from the surface of the semiconductor substrate. At least one part of a thickness area of the first photo-sensing device may overlap at least one part of a thickness area of the second photo-sensing device in a parallel direction extending substantially parallel to the surface of the semiconductor substrate.