Getter-Encapsulated Thermal Detector Cavity for Vacuum Insulation
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Solution Overview
Problem
Existing devices for detecting electromagnetic radiation, such as infrared or terahertz, face challenges in thermal insulation and mechanical strength during manufacturing, particularly when using a hermetic cavity with a getter material, which can reduce performance and is not suitable for multiple thermal detectors.
Innovation Solution
A method involving the production of thermal detectors on a substrate with a mineral sacrificial layer and a getter portion covered by a carbon-based sacrificial layer, where the getter is placed at a distance from the thermal detector and encapsulated by a thin layer, allowing for chemical etching to remove the sacrificial layers while maintaining mechanical integrity and enhancing gas pumping efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a hermetic cavity with getter material is used for thermal insulation, then thermal insulation performance is improved, but the active surface area of the getter material is reduced and mechanical strength during manufacturing is weakened
Solution Approach 1:
The patent divides the sacrificial layer into two distinct segments: a mineral sacrificial layer (first sacrificial layer) and a carbon sacrificial layer (second sacrificial layer). The mineral layer provides mechanical support during manufacturing, while the carbon layer protects the getter material during wet chemical etching. This segmentation allows each layer to fulfill its specific function without compromising the other, resolving the contradiction between mechanical strength and getter surface area.
Solution Approach 2:
The carbon sacrificial layer acts as an intermediary protective barrier between the getter material and the wet chemical etching process. It is deposited after the mineral sacrificial layer and getter material are in place, providing chemically inert protection during the etching step that removes the mineral layer. This intermediary layer enables the removal of the mineral sacrificial layer without damaging the getter material, thus maintaining both mechanical strength during manufacturing and getter surface area.
2Reliability
If a thin carbon sacrificial layer is used to protect getter material, then protection during etching is improved, but mechanical strength during planarization steps is reduced
Solution Approach 1:
The patent segments the sacrificial layer function into two distinct layers: the mineral sacrificial layer provides mechanical strength during planarization and other manufacturing steps, while the carbon sacrificial layer provides chemical protection during wet etching. This segmentation eliminates the need for a thick carbon layer, as the mineral layer carries the mechanical load while the thinner carbon layer focuses on chemical protection.
Solution Approach 2:
The patent introduces a temporal dimension to the protection strategy by sequentially depositing the mineral sacrificial layer first, then the carbon sacrificial layer afterward. This temporal sequencing allows the mineral layer to provide mechanical support during early manufacturing steps including planarization, while the carbon layer provides protection during subsequent etching steps. Each layer is present and functional when needed, resolving the contradiction between mechanical strength and chemical protection.
3Temperature
If two separate cavities are used for thermal detector and getter material, then thermal insulation is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the thermal detector cavity and getter material containment into a single hermetic cavity. The getter material is deposited directly within the same cavity as the thermal detector, eliminating the need for a separate getter cavity and its associated windows or openings. This merging simplifies the encapsulation structure while maintaining thermal insulation, as the getter material can be positioned to minimize thermal interference with the detector.
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 approach improves the mechanical strength and protection of the getter material, enabling better thermal insulation and performance by maintaining the getter's surface area and mechanical stability, suitable for multiple thermal detectors within a hermetic cavity.
Implementation Method 1
removal of the mineral sacrificial layer by a first chemical etching
Implementation Method 2
a carbon sacrificial layer made of a carbon material inert to the first chemical etching
Implementation Method 3
a getter portion made of a metallic material with a getter effect, which ensures gas pumping inside the cavity
Implementation Method 4
production of a thin encapsulation layer comprising an upper part resting on the mineral sacrificial layer and on the carbon sacrificial layer
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 2A~2C
AI summary
The invention relates to a process for manufacturing a detection device comprising at least one thermal detector (20) covered by a mineral sacrificial layer (14, 15), at least one getter portion (13) covered by a carbon-based sacrificial layer (17), and a thin encapsulation layer (31) surrounding the thermal detector and the getter portion. The manufacturing process comprises a step of making a through-opening (16) extending through the mineral sacrificial layer (14, 15) and opening on the substrate (10), and a step of depositing the carbon-based sacrificial layer (17) so as to cover the getter portion (13) located in the through-opening (16), and to entirely fill the through-opening (16).