GaN Carbon Concentration Estimation via Threshold Voltage Shift

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Solution Overview

Problem

There is a need to accurately estimate the carbon concentration in the gallium nitride layer of electronic components, particularly to balance voltage behavior and lifetime, as excessive carbon concentration can reduce the lifetime of gallium nitride transistors.

Innovation Solution

A method involving estimating the electric capacitance, heating the component, measuring the threshold voltage offset, and calculating the nitrogen site carbon concentration in the epitaxial carbon-doped gallium nitride layer, which includes steps like applying a negative bias voltage and calculating the surface and volume concentrations based on the measured capacitance and threshold voltage variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon atoms are introduced into the gallium nitride layer to improve voltage behavior, then voltage behavior is improved, but transistor lifetime decreases due to excessive carbon concentration

Engineering Contradiction:

Improvevoltage behaviorVSAvoidtransistor lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies parameter changes by precisely controlling the carbon concentration in the gallium nitride layer through epitaxial growth parameters. By adjusting the carbon doping level during manufacturing, the method optimizes the balance between voltage behavior improvement and transistor lifetime preservation, avoiding excessive carbon concentration that would harm device longevity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If carbon concentration is increased to optimize voltage behavior, then voltage behavior improves, but measurement and control of carbon concentration becomes more difficult

Engineering Contradiction:

Improvevoltage behaviorVSAvoidcarbon concentration measurement

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces direct carbon concentration measurement with an indirect electrical characterization method. By measuring the threshold voltage offset and capacitance of the device, the method infers the carbon concentration without requiring direct chemical analysis, thus simplifying the measurement process and enabling routine quality control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces threshold voltage offset and capacitance measurements as intermediary parameters that correlate with carbon concentration. These electrical measurements serve as mediators between the carbon doping process and the final device performance, providing a practical means to assess and control carbon concentration through standard electrical testing equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If precise control of carbon concentration is implemented, then manufacturing precision improves, but device complexity increases due to additional measurement and calculation steps

Engineering Contradiction:

Improvecarbon concentration controlVSAvoidmeasurement and calculation process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent achieves multi-functionality by using the same device structure for both operation and characterization. The threshold voltage offset and capacitance measurements are performed using the device's own electrical terminals and standard test equipment, eliminating the need for separate measurement apparatus and reducing overall system complexity despite enhanced manufacturing precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 allows for precise control of carbon concentration, enhancing the manufacturing process by adapting epitaxy parameters to achieve optimal performance in terms of voltage behavior and switching frequency.

Implementation Method 1

heating the component

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

estimating an electric capacitance of a stack interposed between the first layer and a first electrode of the component

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11761920B2Concentration estimation method

Publication Date: 2023.09.19 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method of estimating a nitrogen site carbon concentration, in a first epitaxial layer made of carbon-doped gallium nitride of an electronic component, including steps of: estimating an electric capacitance of a stack interposed between the first layer and a first electrode of the component; heating the component; measuring an offset of a threshold voltage of the component; and deducing therefrom a nitrogen site carbon surface concentration in the first layer.