Stacked Image Sensor Layout for Pre-Arithmetic Noise Removal
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Solution Overview
Problem
Existing image sensors do not effectively remove noise signal components prior to arithmetic operations, leading to suboptimal image quality due to the lack of correlated double sampling (CDS) before signal processing.
Innovation Solution
The image sensor employs a laminated structure with a pixel substrate and an arithmetic operation substrate, where correlated double sampling is executed prior to arithmetic operations using digital signals from photoelectric conversion and noise signals, allowing for noise removal and efficient signal processing without increasing chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correlated double sampling is executed prior to arithmetic operations, then noise signal components are removed and image quality is improved, but device complexity increases due to the need for additional processing circuits
Solution Approach 1:
The patent transitions from planar integration to three-dimensional stacked integration, placing the pixel substrate and arithmetic operation substrate at different vertical levels. This spatial reorganization allows CDS circuits and arithmetic operation circuits to be distributed across multiple layers, reducing in-plane circuit density and complexity while enabling noise removal functionality.
Solution Approach 2:
The image sensor is divided into functionally independent substrates: a pixel substrate for photoelectric conversion and signal generation, and a separate arithmetic operation substrate for CDS and arithmetic processing. This segmentation allows each substrate to be optimized independently, with the pixel substrate focusing on light detection and the arithmetic substrate focusing on noise removal and signal processing.
2Measurement precision
If more circuits are integrated on the pixel substrate to enable CDS and arithmetic operations, then noise removal capability is improved, but the opening ratio of pixels is reduced
Solution Approach 1:
By moving CDS and arithmetic operation circuits from the pixel substrate to a separate arithmetic operation substrate in the vertical dimension, the patent eliminates the need for these circuits to occupy pixel area. This allows pixels to maintain larger opening ratios for light collection while noise removal functionality is preserved on the stacked arithmetic substrate.
Solution Approach 2:
The patent creates a separate arithmetic operation substrate that copies the noise removal and processing functionality from what would otherwise need to be integrated on the pixel substrate. This functional copying enables independent optimization of pixel structure and processing circuitry.
3Area of stationary object
If a laminated structure with separate arithmetic operation substrate is used, then chip area is reduced and pixel opening ratio is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes vertical stacking to integrate multiple functional substrates (pixel substrate and arithmetic operation substrate) in the thickness direction rather than expanding chip area horizontally. This three-dimensional integration reduces the overall chip footprint while maintaining all necessary processing functions, though it requires precise alignment and bonding processes.
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 effective noise removal and improved image quality by executing arithmetic operations with signals from which noise components have been removed, reducing the chip area required for peripheral circuits and maintaining the opening ratio of pixels.
Implementation Method 1
a photoelectric conversion unit that generates an electric charge through photoelectric conversion executed on light having entered therein
Data Source
AI summary
An image sensor includes: a pixel substrate that includes a plurality of pixels each having a photoelectric conversion unit that generates an electric charge through photoelectric conversion executed on light having entered therein and an output unit that generates a signal based upon the electric charge and outputs the signal; and an arithmetic operation substrate that is laminated on the pixel substrate and includes an operation unit that generates a corrected signal by using a reset signal generated after the electric charge in the output unit is reset and a photoelectric conversion signal generated based upon an electric charge generated in the photoelectric conversion unit and executes an arithmetic operation by using corrected signals each generated in correspondence to one of the pixels.