Sputtered Magnesium Diffusion in GaN for Stable P-Type Doping

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Solution Overview

Problem

Gallium-nitride-based semiconductor devices face challenges with magnesium doping due to passivation by hydrogen, high ionization energy, surface decomposition during implantation, and diffusion issues, which affect the formation of p-type regions in GaN materials.

Innovation Solution

A method involving sputtering a magnesium source onto a gallium nitride substrate, followed by annealing to diffuse magnesium and forming a p-type gallium nitride layer, with a capping structure to protect the magnesium source during the annealing process, enabling precise control of magnesium diffusion and activation of dopants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnesium is doped into gallium nitride using conventional implantation methods, then p-type regions can be formed, but surface decomposition occurs during the process

Engineering Contradiction:

Improvep-type region formationVSAvoidsurface decomposition

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A capping layer is deposited over the gallium nitride layer before the magnesium diffusion process. This preliminary protective action prevents surface decomposition during the high-temperature annealing and magnesium diffusion, while still allowing magnesium atoms to diffuse through the capping layer into the GaN layer to form p-type regions.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If magnesium doping is performed to create p-type regions, then device functionality is improved, but hydrogen passivation reduces doping effectiveness

Engineering Contradiction:

Improvedevice functionalityVSAvoiddoping effectiveness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent employs specific annealing temperature and time parameters during the magnesium diffusion process to optimize dopant activation while minimizing hydrogen passivation effects. By carefully controlling these thermal parameters, the method achieves effective p-type doping despite the presence of hydrogen in the GaN structure.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional doping methods are used, then p-type regions can be formed, but high ionization energy limits carrier concentration

Engineering Contradiction:

Improvep-type region formationVSAvoidcarrier concentration

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent replaces conventional ion implantation with a thermal diffusion process where magnesium is introduced through a capping layer and diffuses into the GaN layer during annealing. This substitution of the doping mechanism allows for better control of dopant distribution and activation, overcoming the limitations of high ionization energy associated with traditional methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If magnesium diffusion is performed without protection, then doping can occur, but surface degradation occurs during annealing

Engineering Contradiction:

Improvemagnesium diffusion controlVSAvoidsurface degradation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The capping layer serves as an intermediary between the external environment and the gallium nitride layer during magnesium diffusion. It protects the GaN surface from degradation during high-temperature annealing while permitting magnesium atoms to diffuse through it into the underlying layer, thus enabling controlled doping without surface damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively diffuses magnesium into GaN substrates, overcoming previous challenges by enhancing magnesium diffusion and activation, suitable for various optical, electronic, and opto-electronic devices, and providing improved p-type doping for semiconductor devices.

Implementation Method 1

annealing the substrate structure to diffuse magnesium into the undoped gallium nitride layer

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

depositing a capping structure over the dopant source

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 3

sputtering a dopant source including magnesium onto the undoped gallium nitride layer

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS11881404B2Method and system for diffusing magnesium in gallium nitride materials using sputtered magnesium sources

Publication Date: 2024.01.23 QROMIS INC

AI summary

A method of forming a doped gallium nitride (GaN) layer includes providing a substrate structure, including a gallium nitride layer, forming a dopant source layer over the gallium nitride layer, and depositing a capping structure over the dopant source layer. The method also includes annealing the substrate structure to diffuse dopants into the gallium nitride layer, removing the capping structure and the dopant source layer, and activating the diffused dopants.