Direct Bonding Getter Notch for Thermal Detector Hermeticity
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Solution Overview
Problem
Existing methods for manufacturing electromagnetic radiation detection devices, particularly those using thermal detectors and getter materials, face challenges in mechanical strength and structural degradation during manufacturing, and require complex processes involving copper bonding which may not be available in all technology streams.
Innovation Solution
A method involving the production of a first stack with thermal detectors and a thin encapsulation layer, and a second stack with a getter portion and a holding layer, where the getter portion is assembled into a lateral notch in the encapsulation layer, and the mineral sacrificial layer is removed, followed by deposition of a sealing layer to close the release vent, allowing for direct bonding at room temperature without copper bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper bonding is used to assemble the encapsulation structure, then hermeticity can be achieved, but the manufacturing process becomes complex and copper may not be available in all technology streams
Solution Approach 1:
The invention extracts copper bonding from the manufacturing process and replaces it with direct bonding between silicon layers. The method removes the intermediate copper layer that was previously used to bond the encapsulation structure to the substrate, achieving hermeticity through direct silicon-to-silicon bonding instead.
Solution Approach 2:
The silicon layer serves multiple functions: it acts as both the encapsulation structure and the bonding surface. By making the silicon layer itself bonding-capable through surface activation, the invention eliminates the need for separate copper bonding materials, making the process universally applicable across different technology streams without material availability constraints.
2Device complexity
If the getter portion is placed directly on the substrate, then the structure is simplified, but mechanical strength is reduced and structural degradation occurs during manufacturing
Solution Approach 1:
The invention performs preliminary action by forming a recess in the encapsulation layer before placing the getter portion. This recess provides mechanical support and anchoring for the getter, preventing structural degradation during subsequent manufacturing steps while maintaining a relatively simple overall structure.
Solution Approach 2:
The getter portion is nested within a recess of the encapsulation layer, creating a hierarchical structure where the getter is housed within the encapsulation structure. This nesting provides mechanical support to the getter while maintaining compactness and avoiding excessive structural complexity.
3Strength
If mineral sacrificial layers are used to support the encapsulation structure during manufacturing, then structural integrity is maintained, but the process requires additional chemical etching steps
Solution Approach 1:
The invention merges the sacrificial layer removal step with the getter placement step. The recess in the encapsulation layer is formed by removing mineral sacrificial material, and the getter is simultaneously placed in this recess. This combines what would otherwise be separate operations, reducing overall process complexity.
Solution Approach 2:
The mineral sacrificial layer acts as an intermediary that temporarily supports the encapsulation structure during manufacturing. It is removed through chemical etching after the encapsulation layer is formed, allowing the structure to be maintained during critical manufacturing steps while enabling subsequent getter integration.
4Manufacturing precision
If the encapsulation layer is made thin to improve detector sensitivity, then detection performance improves, but mechanical fragility increases during planarization
Solution Approach 1:
The invention applies local quality by creating a recess in the encapsulation layer at the getter location. This localized modification provides mechanical support where needed (at the getter) while maintaining the thin overall thickness of the encapsulation layer for optimal detector sensitivity. The recess acts as a local reinforcement without compromising global thinness.
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 simplifies the device structure and manufacturing process, enhances mechanical strength, and maintains hermeticity and detection performance while avoiding copper bonding and reducing mechanical fragility during planarization.
Implementation Method 1
an absorbing portion capable of absorbing the electromagnetic radiation to be detected
Implementation Method 2
a getter material which makes it possible to pump the hermetic cavity in which the thermal detector is located
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 1G~2
AI summary
The invention relates to a method for manufacturing a detection device 1 comprising the following steps: ∘ making a stack 10 comprising a thermal detector 20 covered by a mineral sacrificial layer 15, and a thin encapsulation layer 16 having a lateral notch 4; ∘ making a stack 30 comprising a thin retaining layer 33, a getter portion 34 and a thin protective layer 35; ∘ direct bonding of the thin retaining layer 33 to the thin encapsulation layer 16 so that the getter portion 34 is located in the lateral notch 4; ∘ making a vent 17, and removing the mineral sacrificial layer 15 and the thin protective layer 35; ∘ deposition of a thin sealing layer 5 closing the vent 17.