ToF Image Sensor Tap Structure for Power Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image sensing devices, particularly CMOS image sensors, face challenges in efficiently detecting distance using Time-of-Flight (ToF) methods while maintaining low power consumption and high performance.
Innovation Solution
The design incorporates a substrate with pixel regions and taps structured to generate and capture photocharges, featuring a control node, detection node, and control gate configuration that creates an electric potential difference to enhance ToF pixel performance and reduce power consumption by optimizing the arrangement of control nodes and gates within the pixel array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMOS image sensor structures are used for ToF applications, then device complexity is reduced and manufacturing is easier, but ToF pixel performance is insufficient and power consumption is high
Solution Approach 1:
The pixel structure is segmented into distinct functional regions: pixel regions for light detection, taps for charge capture, control nodes for electric potential generation, and control gates for operation control. This segmentation allows each component to be optimized for its specific function, improving overall ToF pixel performance while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the substrate are assigned different doping types and structures: pixel regions with first conductive type, taps with second conductive type, control nodes with specific doping concentrations, and control gates with insulating layers. This local differentiation of properties enables precise control of charge generation, transport, and capture processes, enhancing ToF performance
2Measurement precision
If more control nodes and control gates are added to each pixel, then ToF pixel performance is improved, but power consumption increases
Solution Approach 1:
The control gates are operated in periodic cycles, alternating between active and inactive states to control charge capture at the taps. This periodic operation allows the system to achieve precise distance measurement through time-gated detection while reducing average power consumption by keeping control gates inactive during non-measurement periods
Solution Approach 2:
The control nodes automatically generate the necessary electric potential differences based on the incident light intensity and charge generation in pixel regions. This self-regulating mechanism reduces the need for external power control circuits, lowering overall power consumption while maintaining measurement precision
3Area of stationary object
If control nodes and detection nodes are closely arranged, then device area is reduced, but electric potential difference generation becomes difficult
Solution Approach 1:
The control nodes and detection nodes are arranged in a three-dimensional configuration within the substrate, utilizing vertical depth in addition to horizontal plane positioning. This spatial arrangement allows sufficient electric potential difference generation through the substrate thickness while maintaining compact horizontal footprint, thus reducing overall device area without compromising power generation capability
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 the performance of ToF pixels while minimizing power consumption, enabling accurate distance measurement with reduced power usage, thus addressing the limitations of existing CMOS image sensors in ToF applications.
Implementation Method 1
a plurality of pixel regions included in a substrate and structured to detect incident light and generate photocharges corresponding to an intensity of the incident light
Implementation Method 2
a plurality of taps structured to generate an electric potential difference in the substrate and capture the photocharges generated by the plurality of pixel regions and migrated by the electric potential difference
Data Source
AI summary
An image sensing device may include a plurality of pixel regions included in a substrate, a plurality of taps structured to generate an electric potential difference in the substrate and capture photocharges generated by the plurality of pixel regions and migrated by the electric potential difference, wherein each of the taps comprises a control node disposed in the substrate and doped with a first conductive type impurity, a detection node disposed in the substrate and doped with a second conductive type impurity, and a control gate structured to include a gate electrode and a gate dielectric layer for electrically isolating the gate electrode from the substrate, wherein the control node is disposed at a first side of the detection node, and the control gate is disposed at a second side of the detection node, wherein the second side is an opposite side of the first side.