Silicon Nitride Waveguide Charge Trap Depopulation

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Solution Overview

Problem

Silicon nitride light waveguides in photonic circuits suffer from propagation loss due to charge traps, which affects the accuracy and reproducibility of measurements, especially in biosensing applications where controlled light propagation is crucial.

Innovation Solution

Exposing the silicon nitride light waveguide to a charge carrier exciting condition, such as ultraviolet light or high temperature, to depopulate charge traps, ensuring reliable and reproducible light propagation characteristics by exciting electrons and holes out of these traps, thereby minimizing absorption of light by charge carriers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silicon nitride light waveguide is manufactured using conventional methods, then manufacturing process is simple, but propagation loss occurs due to charge traps

Engineering Contradiction:
Improvelight propagation reliabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by exposing the silicon nitride light waveguide to electromagnetic radiation (such as ultraviolet light) during the manufacturing process, specifically after deposition and before final device assembly. This preliminary exposure depopulates charge traps in advance, preventing propagation loss issues that would otherwise manifest during device operation. The charge carrier exciting condition is applied at an optimal point in the manufacturing sequence to ensure reliable light propagation from the start.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If charge traps are populated in silicon nitride light waveguide, then manufacturing process is straightforward, but measurement accuracy deteriorates

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing ease
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the electromagnetic environment during manufacturing - specifically exposing the silicon nitride layer to electromagnetic radiation with appropriate energy (such as UV light) to change the charge trap population state. This parameter change (from populated to depopulated charge traps) directly improves measurement accuracy by eliminating absorption losses, while the exposure process itself remains a straightforward manufacturing step that can be integrated into existing fabrication workflows.

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

This method ensures that photonic circuits manufactured using this process have predictable and reliable light propagation characteristics, making them suitable for sensitive measurements without propagation loss, enhancing their reliability and reproducibility for applications like biosensing.

Implementation Method 1

exposing the silicon nitride light waveguide to a charge carrier exciting condition for exciting electrons from charge traps in the silicon nitride light waveguide to the conduction band and electron holes from charge traps in the silicon nitride light waveguide to the valence band

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

exposing the silicon nitride light waveguide to a charge carrier exciting condition, such as ultraviolet light or high temperature

Methodology Applied
Scientific EffectThermal excitation: Heat Treatment

Implementation Method 3

By exciting electrons and electron holes, the charge carriers may recombine with localized opposite charge carriers so that the charge traps in the silicon nitride light waveguide may be depopulated

Methodology Applied
Scientific EffectCharge carrier recombination:

Implementation Method 4

free electrons and holes may be trapped by defect states with energies not accessible by a working wavelength of light to be guided through the light waveguide such as not to cause propagation loss in the light waveguide

Methodology Applied
Scientific EffectCharge carrier trapping:

Data Source

PatentEP3499281B1A method for manufacturing of a photonic circuit
Publication Date: 2020.09.23 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP3499281B1 patent drawingFigure 1
  • EP3499281B1 patent drawingFigure 2a~2b
  • EP3499281B1 patent drawingFigure 3~4

AI summary

A method for manufacturing of a photonic circuit including a silicon nitride light waveguide comprises: depositing (102) silicon nitride on a substrate for forming a structure comprising a silicon nitride light waveguide (302) on a substrate; processing (104) the structure for forming the photonic circuit; wherein the processing (104) of the structure comprises the structure being exposed to electromagnetic radiation having an energy sufficiently large to excite electrons to a conduction band in the silicon nitride light waveguide (302); the method further comprising exposing (106) the silicon nitride light waveguide (302) to a charge carrier exciting condition for exciting electrons from charge traps in the silicon nitride light waveguide (302) to a conduction band and electron holes from charge traps in the silicon nitride light waveguide (302) to a valence band for depopulating charge traps.