Variable Thickness Silicon Pixel Light-Receiving Device
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-receiving devices, such as Silicon Photomultipliers (SiPMs), face challenges in achieving high sensitivity and cost-effectiveness, especially when used in distance measurement systems, as thinning semiconductor substrates restrict bonding pad formation and using compound semiconductor substrates is costly. Additionally, these devices require multifunctionality to provide distance information alongside high light-receiving sensitivity.
Innovation Solution
A light-receiving device with a silicon semiconductor substrate featuring pixel regions of varying thicknesses, where a thicker region maintains substrate strength and a thinner region enhances sensitivity, combined with a metal film as a common electrode for improved light reflection and sensitivity adjustment, allowing for different sensitivity settings based on distance measurement needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the semiconductor substrate is thinned to improve light-receiving sensitivity, then the light-receiving sensitivity is improved, but the formation of bonding pads is restricted
Solution Approach 1:
The substrate surface is divided into a light-receiving region with reduced thickness for high sensitivity and a peripheral region with standard thickness for bonding pad formation. This segmentation allows both functions to coexist without interference.
Solution Approach 2:
The substrate thickness is locally adjusted: thinned in the light-receiving region to enhance sensitivity, while maintaining original thickness in the peripheral region to ensure proper bonding pad formation and mechanical strength.
2Measurement precision
If a compound semiconductor substrate is used to improve light-receiving sensitivity, then the light-receiving sensitivity is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of changing the substrate material to compound semiconductor, the invention changes the physical parameter (thickness) of the silicon substrate to achieve high sensitivity, thereby maintaining compatibility with standard silicon fabrication processes and reducing costs.
3Device complexity
If a single photoelectric conversion element is used, then the device structure is simple, but the device cannot provide both high sensitivity and distance information simultaneously
Solution Approach 1:
The photoelectric conversion device is segmented into multiple independent photoelectric conversion elements with different sensitivity characteristics, allowing the device to simultaneously provide high sensitivity detection and distance information by selecting appropriate elements.
Solution Approach 2:
Multiple photoelectric conversion elements with different sensitivities are integrated into a single device, enabling it to perform multiple functions: high sensitivity detection for distant objects and standard detection for nearby objects, thereby achieving multi-functionality.
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
The device achieves multi-functional light-receiving capabilities with adjustable sensitivity, enabling effective distance measurement and reduced manufacturing costs by utilizing a standard silicon semiconductor substrate, while optimizing photoelectric conversion element performance for both short and long distances.
Implementation Method 1
a metal film 15 formed on a back surface of the semiconductor substrate 10
Implementation Method 2
a plurality of first photoelectric conversion elements 71 to 74 formed on a light-receiving surface of the semiconductor substrate 10
Data Source
AI summary
A light-receiving device has a semiconductor substrate that includes a first pixel region that has a first thickness and a second pixel region that has a second thickness less than the first thickness. It has a plurality of first photoelectric conversion elements formed in the first pixel region and a first electrode where their outputs are supplied thereto. It has a plurality of photoelectric conversion elements formed in the second pixel region and a second electrode where their outputs are supplied thereto. It has a common electrode for the first and second photoelectric conversion elements.