GaN Transistor Epitaxial Structure for Clean Passivation Interfaces

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Solution Overview

Problem

The interface between the passivation layer and the aluminum gallium nitride barrier layer in gallium nitride transistors is susceptible to oxygen impurities during deposition, leading to surface roughening, increased gate leakage, and trap energy levels, which deteriorate the device performance.

Innovation Solution

A composite layer with a gradually increasing proportion of silicon nitride is formed on the semiconductor laminated layer, ensuring a smooth interface and preventing impurity introduction, using in situ metal organic chemical vapor deposition (MOCVD) to create a silicon nitride/gallium nitride composite structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PECVD or LPCVD is used to deposit the passivation layer, then the passivation layer can be formed, but the interface between the passivation layer and the aluminum gallium nitride barrier layer becomes susceptible to oxygen impurities, causing surface roughening and increased gate leakage

Engineering Contradiction:

Improvepassivation effectVSAvoidoxygen impurities

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A composite layer comprising a gallium nitride layer and a silicon nitride layer is introduced as an intermediary between the passivation layer and the aluminum gallium nitride barrier layer. This composite layer acts as a protective mediator that prevents oxygen impurities from reaching the interface, thereby eliminating surface roughening and gate leakage while maintaining the passivation function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The composite layer creates an inert environment between the passivation layer and the barrier layer, preventing oxygen impurities from contaminating the interface. The silicon nitride layer specifically provides this inert barrier that blocks oxygen diffusion, ensuring a clean interface without surface roughening.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If the passivation layer is transferred outside the epitaxial equipment, then the deposition process can be completed, but the passivation layer contacts oxygen and other impurities in the air, roughening the surface and introducing trap energy levels

Engineering Contradiction:

Improvedeposition processVSAvoidsurface smoothness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The formation of the composite layer and the passivation layer are merged into a single continuous deposition process within the epitaxial equipment. This integration eliminates the need to transfer the passivation layer outside the equipment, preventing contact with atmospheric impurities while maintaining manufacturing efficiency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The deposition process continues uninterrupted within the epitaxial equipment, with the composite layer formed first and the passivation layer deposited directly onto it without breaking vacuum or exposing to air. This continuous process maintains surface smoothness by preventing impurity contamination throughout the entire deposition sequence.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If a uniform silicon nitride layer is formed, then the sealing properties improve, but the interface with the semiconductor laminated layer may become rough due to corrosion

Engineering Contradiction:

Improvesealing propertiesVSAvoidinterface smoothness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The composite layer has non-uniform silicon nitride distribution: the gallium nitride layer provides a smooth interface with the semiconductor laminated layer, while the silicon nitride layer provides enhanced sealing properties. Each layer performs its specific function locally, achieving both interface smoothness and sealing performance simultaneously.

Inventive Principle:

Principle #3Local quality

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

The method enhances the passivation effect by preventing corrosion and impurity introduction, resulting in improved electrical performance and suitability for large-scale production.

Implementation Method 1

using in situ metal organic chemical vapor deposition (MOCVD) to create a silicon nitride/gallium nitride composite structure

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS20250393289A1Epitaxial structure of gallium nitride transistor and preparation method thereof, and gallium nitride transistor

Publication Date: 2025.12.25 HUNAN SANAN SEMICON CO LTD

AI summary

A gallium nitride transistor is provided. Due to the composite layer including a silicon nitride composite structure, it has better sealing properties, which can effectively prevent the corrosion of the barrier layer and other layers in the semiconductor laminated layer by the passivation layer. Moreover, it ensures that the interface and surface between the passivation layer and the barrier layer are smooth, thereby enhancing the passivation effect and consequently improving the performance of the gallium nitride transistor.