MWIR Emitter Using Tungsten Array and Hermetic Barrier

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Solution Overview

Problem

The existing methods for manufacturing medium wavelength infrared (MWIR) narrow band emitters are inefficient due to low emissivity materials like gold and challenging manufacturing tolerances, which result in low power efficiency and poor control over device parameters.

Innovation Solution

The use of a chemically polished tungsten array combined with a passive hermetic barrier and mirror, along with a metal photonic band gap filter, to create a high-performance MWIR emitter, employing tungsten as a high emissivity material to achieve greater energy densities at the photonic band gap structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If gold is used as the emitter material, then the device has good electrical conductivity, but the emissivity is very low resulting in low power efficiency

Engineering Contradiction:

Improvepower efficiencyVSAvoidemissivity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent changes the material parameter from gold to tungsten, which fundamentally alters the emissivity characteristic. Tungsten provides high emissivity in the infrared range, directly resolving the low power efficiency problem while maintaining structural integrity for device reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining tungsten emitter elements with silicon substrate and silicon nitride barrier layers. This composite approach leverages the high emissivity of tungsten while utilizing the structural and protective properties of silicon and silicon nitride to maintain overall device reliability

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If holes are etched in substrate and heating is applied from behind, then the structure acts as a filter, but the manufacturing tolerances are difficult to achieve

Engineering Contradiction:

Improvefilter performanceVSAvoidmanufacturing tolerances

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of etching holes in the substrate and heating from behind, the patent inverts the approach by depositing tungsten emitter patterns directly onto the silicon substrate surface. This inversion simplifies the manufacturing process, making tolerances easier to control while achieving the same infrared filtering function through the photonic bandgap structure

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the mechanical etching process with a deposition-based approach. By using physical vapor deposition or chemical vapor deposition to form tungsten emitter patterns, the process becomes more controllable and less sensitive to manufacturing tolerances compared to traditional wet or dry etching methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If tungsten is used as emitter material, then the emissivity is high improving power efficiency, but the device parameters require better control

Engineering Contradiction:

Improvepower efficiencyVSAvoiddevice parameters control

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent applies preliminary planarization to the silicon substrate surface before depositing the tungsten emitter material. This preliminary action ensures a flat, uniform surface that facilitates precise control of emitter thickness and pattern dimensions, directly addressing the device parameters control requirement while maintaining the high emissivity benefit of tungsten

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces silicon nitride as an intermediary barrier layer between the silicon substrate and tungsten emitter. This intermediary layer provides a controlled interface that facilitates precise deposition control of the tungsten emitter thickness and pattern, enabling better device parameters control while preserving the high power efficiency of tungsten

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the efficiency of MWIR emitters by allowing better control over device parameters and increasing energy densities, leading to improved infrared emission performance.

Implementation Method 1

By using a high emissivity material like tungsten we are able to develop greater energy densities at the photonic band gap structure

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

the heater of the present invention is a metal photonic band gap (PBG) filter

Methodology Applied

Scientific EffectPhotonic band gap: Photonic Crystal

Data Source

PatentUS8946739B2Process to fabricate integrated MWIR emitter

Publication Date: 2015.02.03 GULA CONSULTING LLC

AI summary

A device for medium wavelength infrared emission and a method for the manufacture thereof is provided. The device has a semiconductor substrate; a passive hermetic barrier disposed upon the substrate, and an emitter element disposed within said hermetic barrier; and a mirror.