Thermopile Infrared Sensor Array With Thin Insulating Membrane
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Solution Overview
Problem
Existing thermopile infrared sensor arrays face challenges in achieving high thermal resolution while maintaining cost-effectiveness, as they often require large chip sizes, expensive vacuum housing, or mechanical choppers, which increase production costs and complexity.
Innovation Solution
A thermopile infrared sensor array design featuring a thin non-conducting membrane on a semiconductor substrate with recessed thermopile elements and edge-mounted electronic components, including preamplifiers, which minimizes thermal influence and allows for compact, cost-effective production without vacuum housing or mechanical choppers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electronic components are integrated on the sensor chip, then device complexity is reduced, but thermal influence from power loss increases noise and degrades thermal resolution
Solution Approach 1:
The device is segmented into distinct functional zones: a central sensor area free of electronic components and peripheral edge areas where electronic components are located. This spatial segmentation prevents thermal influence from electronics on the sensitive sensor elements while maintaining integration benefits.
Solution Approach 2:
Thermal isolation structures act as intermediaries between the sensor elements and electronic components, blocking heat transfer paths. These structures include thermal barriers and isolated mounting configurations that allow electrical connectivity while preventing thermal coupling.
2Manufacturing precision
If a large chip size is used, then manufacturing precision and thermal resolution are improved, but manufacturing costs increase
Solution Approach 1:
A thin membrane structure is employed to support the sensor elements. This thin-film approach reduces the overall chip thickness and material usage while maintaining structural integrity and thermal isolation, enabling high-resolution sensing on a cost-effective platform.
Solution Approach 2:
The design transitions from a planar layout to a three-dimensional structure with recesses and elevated sensor elements. This dimensional change allows for better thermal management and optical access while maintaining a compact footprint, reducing the need for large chip sizes.
3Measurement precision
If the sensor chip is sealed in a vacuum-tight housing, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The vacuum housing requirement is extracted and eliminated by redesigning the sensor structure to be inherently stable in ambient conditions. The sensor elements and membrane are designed to withstand atmospheric pressure without requiring vacuum sealing, simplifying the overall device architecture.
Solution Approach 2:
The design accepts ambient environmental conditions rather than maintaining a controlled vacuum environment, effectively replacing the expensive vacuum housing with a simple atmospheric seal. This approach prioritizes cost-effectiveness for applications where absolute vacuum stability is not critical.
4Ease of manufacture
If wet etching technology is used, then manufacturing ease is improved, but chip size becomes large leading to high costs
Solution Approach 1:
The etching process parameters are optimized to achieve the desired membrane thickness and sensor element geometry with minimal material removal. This allows for precise control of the membrane properties and sensor characteristics while reducing the overall chip area required.
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 design achieves high thermal resolution with reduced noise and manufacturing costs, enabling efficient thermal decoupling and mechanical stabilization, while maintaining a compact sensor size.
Implementation Method 1
a thermopile infrared sensor array consisting of a sensor chip with a number of thermopile sensor elements constructed on a semiconductor substrate
Implementation Method 2
a thin membrane of a nonconducting material is arranged on the semiconductor substrate of the sensor chip
Data Source
AI summary
A thermopile infrared sensor array, comprises a sensor chip with a number of thermopile sensor elements, made from a semiconductor substrate and corresponding electronic components. The sensor chip is mounted on a support circuit board and enclosed by a cap in which a lens is arranged. The aim is the production of a monolithic infrared sensor array with a high thermal resolution capacity with a small chip size and which may be economically produced. The aim is achieved by arranging a thin membrane made from non-conducting material on the semiconductor substrate of the sensor chip on which the thermopile sensor elements are located in an array. Under each thermopile sensor element, the back side of the membrane is uncovered in a honeycomb pattern by etching and the electronic components are arranged in the boundary region of the sensor chip. An individual pre-amplifier with a subsequent low-pass filter may be provided for each column and each row of sensor elements.