Infrared Filter Film Layer Nitride Isolation Barrier

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Solution Overview

Problem

Conventional multi-layer interference optical films for infrared filters are costly and prone to wavelength drift due to instability caused by oxygen atoms combining with silicon, requiring thick layers and limited by hydrogen gas availability in manufacturing.

Innovation Solution

Incorporating a nitride film isolation layer between silicon-based and oxide layers in the infrared filter film structure to prevent oxygen diffusion and enhance stability, with the nitride film being silicon nitride, aluminum nitride, niobium nitride, tantalum nitride, or zirconium nitride, and using silicon dioxide as the oxide layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple thick film layers are used to block visible light band, then infrared filtering performance is improved, but manufacturing cost increases

Engineering Contradiction:

Improveinfrared filtering performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the optical filter into multiple functional layers with distinct roles: silicon-based layers for infrared transmission, oxide layers for visible light blocking, and nitride isolation layers for stability. This segmentation allows each layer to be optimized independently, achieving effective infrared filtering without requiring excessive thickness, thereby controlling manufacturing costs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structures combining silicon-based materials, oxide materials, and nitride materials in a multi-layer configuration. This composite approach leverages the complementary properties of each material to achieve both effective infrared filtering and visible light blocking with reduced overall thickness, improving manufacturing efficiency.

Inventive Principle:

Principle #40Composite materials

2Length of stationary object

If oxide layer is coated on silicon layer to reduce film thickness, then film thickness is reduced, but wavelength drift occurs due to oxygen diffusion

Engineering Contradiction:

Improvefilm thicknessVSAvoidwavelength stability

Core Design Contradiction:

Length of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent introduces a nitride isolation layer as an intermediary between the silicon-based layer and the oxide layer. This intermediate layer acts as a diffusion barrier that prevents oxygen atoms from migrating into the silicon-based layer, thereby eliminating the cause of wavelength drift while allowing the oxide layer to maintain its visible light blocking function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The nitride isolation layer is positioned beforehand between the silicon-based and oxide layers to preemptively block oxygen diffusion pathways. This prior protective measure prevents the chemical interaction that would otherwise cause wavelength instability, ensuring long-term operational stability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If multi-layer interference optical films are formed by alternate stacking of hydrides and oxides, then filtering performance is improved, but production becomes inconvenient due to hydrogen gas limitations

Engineering Contradiction:

Improvefiltering performanceVSAvoidproduction convenience

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material composition parameter by replacing hydrogen-containing silane-based materials with silicon-based materials that do not require hydrogen gas in the deposition process. This parameter change maintains the desired optical filtering performance while eliminating the production constraints associated with hydrogen gas availability and safety.

Inventive Principle:

Principle #35Parameter changes

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 solution improves the stability and quality of the infrared filter film, reducing wavelength drift and enabling more accurate infrared light detection, particularly in lidar devices by enhancing the film's resistance to environmental changes.

Implementation Method 1

the at least one isolation layer being disposed between the at least one silicon-based layer and the at least one oxide layer... oxygen atoms of the oxide layer can be prevented from diffusing into the silicon-based layer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

most optical coating structures are multi-layer interference optical films

Methodology Applied

Scientific EffectOptical interference: Interference

Data Source

PatentUS20240402404A1Infrared filter film layer and infrared filter structure

Publication Date: 2024.12.05 TAIWAN COLOR OPTICS

AI summary

An infrared filter film layer and an infrared filter structure are provided. The infrared filter film layer includes at least one silicon-based layer, at least one isolation layer, and at least one oxide layer that are stacked with each other. The at least one isolation layer is disposed between the at least one silicon-based layer and the at least one oxide layer. Through this configuration, the infrared filter film layer has good quality, such that an amount of wavelength drift is small in application. The infrared filter structure includes a light-transmitting substrate and the infrared filter film layer.