InGaN Growth Substrate Mesas with Controlled Porosification

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Solution Overview

Problem

Existing methods for manufacturing growth substrates for InGaN diodes require complex spatially localized dopant implantations to achieve mesas with different doping levels, complicating the production of diodes that can emit or detect light at various wavelengths.

Innovation Solution

A method involving the production of a crystalline stack with mesas of varying deformabilities by localized etching and electrochemical porosification, eliminating the need for spatially localized dopant implantations, where mesas are categorized based on their porosity and epitaxial regrowth portions to achieve diodes emitting at different wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If spatially localized implantation of dopants is performed to obtain mesas with various doping levels, then the mesas can produce diodes emitting at different wavelengths, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvewavelength emission capabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the physical-chemical parameters of the mesas by controlling the degree of porosification through electrochemical treatment. By varying the porosification conditions (time, voltage, electrolyte composition), different mesa regions develop different porosity levels, which directly control the indium incorporation rate during epitaxial regrowth, thereby enabling different emission wavelengths without spatially localized dopant implantation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/chemical process of spatially localized dopant implantation with an electrochemical porosification process. Instead of physically implanting dopants at specific locations, the method uses electrical fields and chemical reactions to create porosity patterns that indirectly control the compositional gradients during epitaxial growth, simplifying the manufacturing approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If electrochemical porosification is used to create mesas with different doping levels, then the manufacturing process is simplified, but the precision of controlling porosity and deformability varies

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidporosity control precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary patterning actions to the substrate before electrochemical porosification, such as depositing mask layers or creating initial surface structures. These preliminary features guide the subsequent porosification process, ensuring that porosity develops in the desired spatial patterns with controlled gradients, thereby improving precision while maintaining the simplicity of the electrochemical approach

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback control during the electrochemical porosification process by monitoring parameters such as current density, voltage, and porosity development in real-time. Based on this feedback, the process conditions are dynamically adjusted to maintain precise control over the porosity gradients, ensuring consistent mesa deformability and emission wavelength control

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 allows for the production of InGaN diodes that can natively emit or detect light at various wavelengths without the need for complex dopant implantations, simplifying the manufacturing process and enhancing the production of RGB-emitting microscreens.

Implementation Method 1

non-photo-assisted electrochemically porosifying the lower portions of only the mesas M1 and M3

Methodology Applied

Scientific EffectElectrochemical porosification: Electrolysis

Implementation Method 2

producing mesas of three categories M1, M2, M3, by localised etching of the crystalline stack

Methodology Applied

Scientific EffectLocalized etching: Ablation

Data Source

PatentUS20240213398A1Method for manufacturing a growth substrate including mesas of various deformabilities, by etching and electrochemical porosification

Publication Date: 2024.06.27 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for manufacturing a growth substrate adapted to produce by epitaxy a matrix of diodes based on InGaN, including the following steps of:producing a crystalline stack including, from a conductive buffer layer: a lower layer based on doped GaN; then a separation intermediate layer, based on InGaN; then an upper layer (14) based on AlGaN;producing mesas of three categories M1, M2, M3, by localised etching of the crystalline stack;eliminating, by etching, the upper portion of at least the mesas M3, the upper portion of the mesas M1 being preserved; thennon-photo-assisted electrochemically porosifying the lower portions of only the mesas M1 and M3, the lower portion of the mesas M2 being non-porosified.