LWIR Sensor Pixel Array Using MTJ Layout for Higher Sensitivity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing long-wave infrared sensors, particularly quantum type LWIR sensors, are limited by high cost, vacuum requirements, and restricted infrared light reaction, making them unsuitable for civil use, while thermal type LWIR sensors face challenges in sensitivity due to low temperature coefficient of resistance (TCR) in magnetic tunnel junction devices.

Innovation Solution

A long-wave infrared sensor design incorporating a pixel array with magnetic tunnel junction devices arranged in a 2D manner, featuring a protective layer removal to minimize thermal capacity, and a parallel electrical connection to enhance sensitivity, utilizing a matrix of M×N magnetic tunnel junction devices with variable and fixed magnetization directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If quantum type LWIR sensors are used, then detectivity and NETD characteristics are improved, but cost increases and vacuum maintenance is required

Engineering Contradiction:

ImprovedetectivityVSAvoidvacuum maintenance requirement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive quantum type LWIR sensors with thermal type LWIR sensors that use magnetic tunnel junction devices. These thermal sensors do not require vacuum maintenance and are suitable for civil applications, effectively substituting a complex, maintenance-intensive system with a simpler, more maintainable one.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the quantum mechanical effect-based sensors with thermal effect-based sensors. The magnetic tunnel junction devices operate based on thermal principles (resistance change with temperature) rather than quantum photoconductive effects, eliminating the need for vacuum environments and complex cooling systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If thermal type LWIR sensors are used, then cost is reduced, but sensitivity decreases due to low temperature coefficient of resistance

Engineering Contradiction:

ImprovecostVSAvoidsensitivity

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent modifies the magnetic tunnel junction devices by changing key parameters: increasing the thickness of the insulating layer (to 1-100 nm), adjusting the magnetization directions of the magnetic layers, and optimizing the resistance characteristics. These parameter changes increase the temperature coefficient of resistance, thereby improving sensitivity while maintaining the thermal type sensor's cost advantages.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures in the magnetic tunnel junction devices, combining different magnetic layers (with varying magnetization directions) and insulating layers. This composite approach allows optimization of both the temperature coefficient of resistance and the overall sensor performance, achieving higher sensitivity without requiring expensive quantum type sensors.

Inventive Principle:

Principle #40Composite materials

3Area of moving object

If magnetic tunnel junction devices are arranged closely, then device density is improved, but thermal noise increases

Engineering Contradiction:

Improvedevice densityVSAvoidthermal noise

Core Design Contradiction:

Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent introduces empty spaces between adjacent magnetic tunnel junction devices in the pixel array. This local structural modification reduces thermal noise by minimizing thermal coupling between devices while maintaining acceptable device density. The empty spaces act as thermal isolators, allowing each device to operate independently with reduced interference.

Inventive Principle:

Principle #3Local quality

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

The sensor design improves sensitivity by increasing the temperature coefficient of resistance (TCR), enhancing thermal image conversion capabilities, and reducing thermal noise, making it suitable for both military and civil applications.

Implementation Method 1

a resistance of each of the plurality of magnetic tunnel junction devices changes according to temperature

Methodology Applied

Scientific EffectTemperature coefficient of resistance (TCR): Thermistor

Implementation Method 2

the second magnetic layer may have a variable magnetization direction, and wherein the first magnetic layer may have a fixed magnetization direction

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS12504329B2Long-wave infrared sensor and electronic device including the same

Publication Date: 2025.12.23 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are a long-wave infrared sensor and an electronic device including the same. The long-wave infrared sensor and the electronic device including the same include a pixel array including a plurality of pixels, an optical absorber layer arranged on the pixel array, and a drive circuit configured to drive the pixel array, wherein each of the plurality of pixels for a long-wave infrared sensor includes a lower electrode and an upper electrode which are arranged apart from each other, and a plurality of magnetic tunnel junction devices arranged regularly between the lower electrode and the upper electrode and electrically connected to each other in parallel, and the plurality of magnetic tunnel junction devices are arranged apart from each other with an empty space therebetween.