Getter-Encapsulated Thermal Detector Stack for Etch Protection

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Solution Overview

Problem

Existing devices for detecting electromagnetic radiation, such as infrared or terahertz radiation, face challenges in ensuring the mechanical strength of the detector stack and protecting the getter material during the fabrication process, particularly when using mineral sacrificial layers and carbon-containing sacrificial layers.

Innovation Solution

A process for fabricating a device for detecting electromagnetic radiation involves producing a thermal detector on a substrate covered by a mineral sacrificial layer, a getter segment covered by a carbon-containing sacrificial layer, and a thin encapsulation layer. The mineral sacrificial layer is removed via a first chemical etch, and the carbon-containing sacrificial layer is removed via a second chemical etch, with the getter segment being placed in contact with the substrate at a distance from the thermal detector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thin carbon-containing sacrificial layer is used to protect the getter material, then the getter material is protected during wet chemical etch, but the mechanical strength of the detector stack deteriorates during planarization steps

Engineering Contradiction:

Improveprotection of getter materialVSAvoidmechanical strength of detector stack

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent uses a composite sacrificial layer structure combining a carbon-containing layer (for chemical protection) with a structural support layer (for mechanical strength). This composite approach allows the carbon layer to protect the getter during wet etching while the supporting structural layer maintains the mechanical integrity of the detector stack during planarization and subsequent processing steps.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces an intermediary structural layer between the carbon-containing sacrificial layer and the getter material. This intermediary layer acts as a mechanical support that prevents the thin carbon layer from compromising the overall structural strength, while still allowing the carbon layer to fulfill its protective function during chemical etching processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If the getter segment is placed close to the thermal detector, then the active area of the getter is maximized, but the mechanical strength of the stack deteriorates during fabrication

Engineering Contradiction:

Improveactive area of getter materialVSAvoidmechanical strength during fabrication

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

The patent segments the getter material into a dedicated getter segment that is spatially separated from the thermal detector by a specific distance. This segmentation allows the getter segment to be positioned optimally for both maintaining mechanical strength during fabrication and providing sufficient active area for gas pumping, resolving the contradiction between proximity and structural integrity.

Inventive Principle:

Principle #1Segmentation

3Reliability

If mineral sacrificial layers are used to protect the thermal detector, then the thermal detector is protected during fabrication, but the mechanical strength of the stack deteriorates

Engineering Contradiction:

Improveprotection of thermal detectorVSAvoidmechanical strength of detector stack

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent employs a composite sacrificial layer system where mineral sacrificial layers provide thermal detector protection during fabrication, while additional structural support layers are incorporated to maintain mechanical strength. This composite approach ensures both protective functions are fulfilled without compromising structural integrity.

Inventive Principle:

Principle #40Composite materials

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 process enhances the mechanical strength of the detector stack and effectively protects the getter material, improving the overall performance and reliability of the detecting device by ensuring the active area of the getter material is increased and its performance is maintained.

Implementation Method 1

removing the mineral sacrificial layer via the first chemical etch

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 2

removing the carbon-containing sacrificial layer via the second chemical etch

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 3

a getter material, which pumps gas from the cavities

Methodology Applied

Scientific EffectGettering: Gettering

Data Source

PatentUS12203811B2Process for manufacturing a device for detecting electromagnetic radiation, comprising a getter material

Publication Date: 2025.01.21 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A process for manufacturing a detection device having at least one thermal detector covered by a mineral sacrificial layer, at least one getter portion covered by a carbon-based sacrificial layer, and a thin encapsulation layer surrounding the thermal detector and the getter portion includes a making a through-opening extending through the mineral sacrificial layer and opening on the substrate. The carbon-based sacrificial layer is deposited so as to cover the getter portion located in the through-opening and to entirely fill the through-opening.