Split-Chip Solid-State Imaging for Dark Current Noise Reduction
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Solution Overview
Problem
Conventional Dynamic Vision Sensors (DVS) suffer from noise characteristic deterioration due to dark current flowing from photoelectric conversion elements into pixel circuits, which are integrated on the same substrate, leading to reduced light reception efficiency and transistor noise issues.
Innovation Solution
A solid-state imaging device is designed with photoelectric conversion elements and detection units on separate chips, reducing dark current ingress and improving noise characteristics by separating the photoelectric conversion elements and pixel circuits, thereby enhancing light reception efficiency and transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If photoelectric conversion elements and pixel circuits are integrated on the same substrate, then device complexity is reduced and manufacturing is simplified, but noise characteristics deteriorate due to dark current flowing from photoelectric conversion elements into transistors
Solution Approach 1:
The device is divided into two separate chips: a first chip containing photoelectric conversion elements and a second chip containing pixel circuits. This segmentation physically separates the sources of dark current from the sensitive transistor circuits, eliminating the noise problem while maintaining functional integration through chip-to-chip connections.
Solution Approach 2:
The pixel circuits are extracted from the photoelectric conversion substrate and placed on a separate chip. This extraction removes the harmful interaction between dark current from photoelectric elements and the transistors in pixel circuits, allowing each component to be optimized independently on its own substrate.
2Manufacturing precision
If photoelectric conversion elements and pixel circuits are integrated on the same substrate, then manufacturing precision requirements are reduced, but light reception efficiency decreases due to dark current interference
Solution Approach 1:
By segmenting the device into separate chips for photoelectric conversion and signal processing, the patent eliminates dark current interference that would otherwise reduce light reception efficiency. Each chip can be manufactured and optimized independently, then connected through standardized interfaces.
Solution Approach 2:
The pixel circuits are extracted from the photoelectric conversion substrate, removing the source of dark current interference. This allows photoelectric conversion elements to operate with higher efficiency since their dark current no longer directly affects the pixel circuit transistors.
3Object-affected harmful factors
If photoelectric conversion elements and pixel circuits are separated onto different chips, then noise characteristics improve by reducing dark current ingress, but device complexity increases
Solution Approach 1:
The device is segmented into specialized chips: photoelectric conversion elements on one chip and pixel circuits on another. This segmentation improves noise characteristics by physical separation while managing complexity through modular design with standardized connection interfaces.
Solution Approach 2:
Connection structures (such as bump bonds or wire bonds) act as intermediaries between the photoelectric conversion chip and the pixel circuit chip. These intermediaries enable signal transmission while maintaining the physical separation needed to prevent dark current interference, thus improving noise characteristics.
4Reliability
If photoelectric conversion elements and pixel circuits are separated onto different chips, then light reception efficiency improves by isolating dark current sources, but manufacturing complexity increases
Solution Approach 1:
By segmenting the device into separate chips for photoelectric conversion and signal processing, the patent improves light reception efficiency by eliminating dark current interference. The modular segmented structure allows each chip to be manufactured using optimized processes, then assembled together.
Solution Approach 2:
The pixel circuits are extracted from the photoelectric conversion substrate, allowing photoelectric elements to achieve higher light reception efficiency without dark current contamination. The extracted pixel circuits can be manufactured separately on optimized substrates and then integrated through standard packaging techniques.
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 effectively reduces noise characteristics and improves light reception efficiency by isolating the photoelectric conversion elements and pixel circuits, leading to better performance in high-speed imaging applications.
Implementation Method 1
a plurality of photoelectric conversion elements arranged in a two-dimensional grid shape in a matrix direction and each generating a charge corresponding to a received light amount
Data Source
AI summary
Improvement of noise characteristics is achievable. A solid-state imaging device according to an embodiment includes a plurality of photoelectric conversion elements (333) arranged in a two-dimensional grid shape in a matrix direction and each generating a charge corresponding to a received light amount, and a detection unit (400) that detects a photocurrent produced by the charge generated in each of the plurality of photoelectric conversion elements. A chip (201a) on which the photoelectric conversion elements are disposed and a chip (201b) on which at least a part of the detection unit is disposed are different from each other.