Ion Implantation Refractive Index Tuning for Photonic Circuits

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Solution Overview

Problem

Photonic circuits on silicon are sensitive to temperature variations, leading to performance drops and malfunctions due to the intrinsic sensitivity of silicon's refractive index, which existing solutions attempt to mitigate through energy-intensive active thermal control or complex material modifications during manufacturing.

Innovation Solution

A method for post-manufacturing spectral property adjustments of photonic circuits using localized ion implantations to modify the refractive index of waveguides, allowing for recalibration without adding materials to the guide/encapsulation interface, and enabling passive phase adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If active thermal control using heaters or electrodes is used to manage temperature variations, then the spectral properties of photonic circuits can be dynamically adjusted, but energy consumption increases significantly

Engineering Contradiction:
Improvespectral property adjustmentVSAvoidenergy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by modifying the refractive index of the waveguide through ion implantation during the manufacturing process (BEOL stage). This pre-adjustment compensates for manufacturing uncertainties and temperature sensitivity before the circuit is deployed, eliminating the need for continuous energy-intensive active thermal control during operation.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If additional interface material is added to the waveguide/encapsulation interface for post-manufacturing adjustment, then spectral properties can be readjusted, but manufacturing complexity increases

Engineering Contradiction:
Improvepost-manufacturing readjustmentVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the physical-chemical parameters of the existing waveguide material by implanting ions (such as germanium, carbon, or nitrogen) into the silicon waveguide. This modifies the refractive index of the waveguide core directly, providing a post-manufacturing adjustment mechanism without adding any additional materials or interfaces to the waveguide structure.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If ion implantation is used to modify the refractive index after manufacture, then spectral recalibration is achieved without adding materials, but the process must be precisely controlled

Engineering Contradiction:
Improveintegration into production lineVSAvoidimplantation control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The ion implantation is performed as a preliminary action during the BEOL (Back-End Of Line) manufacturing stage, before the final encapsulation is completed. This timing allows for precise control of the implantation parameters (energy, dose, location) while the waveguide structure is still accessible, and the effects can be measured and adjusted before final assembly.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback by measuring the spectral properties of the photonic circuit after ion implantation and using this information to determine whether additional implantation is needed. This iterative process allows for precise control of the refractive index modification, ensuring the circuit meets its spectral specifications.

Inventive Principle:
Principle #23Feedback

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 reduces energy consumption and manufacturing complexity by allowing precise spectral recalibration of photonic circuits, minimizing the impact of manufacturing uncertainties and temperature variations, while maintaining compatibility with existing active control methods.

Implementation Method 1

a method for adjusting the properties of a photonic circuit to recalibrate them with the expected properties... said method comprising the step of modifying the refractive index of at least one zone of said region in which the light remains confined, characterized in that this step is carried out by means of ion implantation in the at least one zone

Methodology Applied
Scientific EffectIon implantation: Ion Implantation

Data Source

PatentEP3078996B1Method for adjusting the properties of a photonic circuit by ion implantation after manufacturing, waveguide and photonic circuit thus adjusted
Publication Date: 2019.09.18 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3078996B1 patent drawingFigure 1~2b
  • EP3078996B1 patent drawingFigure 3~4
  • EP3078996B1 patent drawingFigure 5(a)~6

AI summary

The invention relates to a method for adjusting the properties of a photonic circuit to match desired properties. The photonic circuit comprises a waveguide (10) which includes a light propagation region (20), characterized in that it includes a step for modifying the refractive index of at least one area of ​​said region, said step being implemented by means of ion implantation in at least one area (21). It extends to a waveguide whose light propagation region has at least one area with a refractive index modified by ion implantation in which the light remains confined, as well as to a photonic circuit incorporating such a waveguide.