Suspended Membrane Radiation Sensor for High Fill Factor Arrays
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Solution Overview
Problem
Existing thermal sensor arrays face challenges with low fill factor and increased response time due to significant thermal mass and underlying support structures, limiting scalability and performance.
Innovation Solution
A radiation sensor design featuring a substrate with electronic circuitry, an intermediate conductive layer, a lower separation layer with high thermal resistance, and an absorptive layer, which reduces thermal mass and enhances fill factor, allowing for faster response times and improved radiation detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is well thermally isolated to achieve greater temperature change per unit of radiant power, then the temperature sensitivity is improved, but the response time is extended due to slower heat dissipation
Solution Approach 1:
The patent changes the thermal parameters of the sensor by using a suspended membrane structure with optimized thickness and material properties. The membrane is designed with specific thermal conductivity and heat capacity values to achieve the desired balance between temperature sensitivity and response time, allowing the sensor to reach thermal equilibrium faster while maintaining high sensitivity to radiant power changes.
Solution Approach 2:
The sensor is segmented into distinct functional layers including the suspended membrane, absorptive layer, and support structure. This segmentation allows each component to be optimized independently - the membrane for thermal isolation and sensitivity, the absorptive layer for radiation capture, and the support structure for mechanical stability - thereby resolving the contradiction between sensitivity and response time.
2Measurement precision
If the sensor array uses traditional pixel designs with support structures like legs or serpentines for thermal isolation, then the thermal performance is improved, but the fill factor is reduced due to the support structures consuming integrated circuit real estate
Solution Approach 1:
The patent transitions from planar thermal isolation structures (legs and serpentines in the same plane as the pixel) to a three-dimensional suspended membrane structure. This dimensional change allows the thermal isolation function to be achieved vertically above the pixel area rather than laterally within it, thereby maintaining high fill factor while preserving thermal performance.
Solution Approach 2:
The suspended membrane structure serves as a simplified copy of the thermal isolation function previously achieved by complex support structures. Instead of using elaborate leg or serpentine configurations, the patent uses a simple suspended membrane that replicates the thermal isolation effect with minimal area consumption, thereby improving fill factor while maintaining thermal performance.
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 design achieves a high fill factor thermal sensor array with reduced thermal mass, leading to better signal-to-noise ratio and faster response times, while maintaining compatibility with existing manufacturing technologies.
Implementation Method 1
an absorptive layer over the top layer and electrically connected to the intermediate conductive layer. The absorptive layer produces the transduction signal that is proportional to an amount of radiation incident on the absorptive layer
Implementation Method 2
a lower separation layer with a high coefficient of thermal resistance partially separating the intermediate conductive layer from the electronic circuitry
Data Source
AI summary
System and method for detecting and imaging radiation. A preferred embodiment comprises a substrate with electronic circuitry to detect changes in a transduction signal, an intermediate conductive layer disposed above and electrically connected to the electronic circuitry, and a lower separation layer with a high coefficient of thermal resistance that partially separates the intermediate conductive layer from the electronic circuitry. The preferred embodiment also includes a top layer disposed above the intermediate conductive layer and an absorptive layer overlying the top layer, with the absorptive layer being electrically connected to the intermediate conductive layer. The absorptive layer produces a transduction signal that is proportional to an amount of radiation incident on the absorptive layer. The vertical fabrication of the radiation sensor allows for sensor arrays with a good fill factor, permitting the creation of sensor arrays with high resolution while maintaining low costs.