AlGaN Intermediate Layers Seal Defects in GaN Chips

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Solution Overview

Problem

Optoelectronic semiconductor chips face challenges with impermeability to liquid chemicals, leading to reduced production yield and reliability due to dislocations and defects like cracks and holes in the semiconductor material, which allow chemical penetration and affect radiation efficiency and current flow.

Innovation Solution

Incorporating epitaxially grown intermediate layers based on Al x Ga 1 - x N within the n-doped layer sequence, these layers have a specific chemical permeability lower than the surrounding semiconductor layers, effectively sealing cracks and holes, reducing chemical penetration and enhancing chip reliability and yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional semiconductor layer sequences are used, then manufacturing simplicity is maintained, but impermeability to liquid chemicals deteriorates due to dislocations and defects

Engineering Contradiction:
Improveimpermeability to liquid chemicalsVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The n-doped layer sequence is segmented by inserting intermediate layers based on AlGaN at specific positions. These intermediate layers divide the continuous n-doped layer into sections, creating a multi-layer structure that blocks chemical penetration paths while maintaining the overall functional integrity of the semiconductor device

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Intermediate layers based on AlGaN serve as intermediary barrier layers between the n-doped layer sequence and the active zone. These intermediate layers have different material composition (AlGaN versus GaN) and doping characteristics, creating a chemical and structural barrier that prevents direct penetration of liquid chemicals through dislocations and defects in the semiconductor layers

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If intermediate layers are inserted to block chemical penetration, then reliability improves, but manufacturing complexity increases

Engineering Contradiction:
Improveproduction yieldVSAvoidepitaxial growth complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The intermediate layers are created by changing epitaxial growth parameters during the growth process. By adjusting composition parameters (Al content in AlGaN) and doping parameters (nitrogen concentration) during specific growth stages, the intermediate layers with desired barrier properties are formed in-situ, integrating the complex multi-layer structure into a single epitaxial growth process

Inventive Principle:
Principle #35Parameter changes

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 intermediate layers significantly reduce permeability to nitric acid and vapors, increasing production yield and reliability by sealing defects without eliminating them, thus maintaining crystal lattice imperfections while preventing chemical damage and improving radiation efficiency.

Implementation Method 1

The intermediate layers have a specific chemical permeability to nitric acid that is lower than a specific chemical permeability of regions or layers of the semiconductor layer sequence adjoining the intermediate layers

Methodology Applied
Scientific EffectPermeation resistance:

Implementation Method 2

An optoelectronic semiconductor chip with intermediate layers based on AlGaN is specified. The semiconductor layer sequence comprises an epitaxially grown semiconductor layer sequence based on AlGaN and/or InAlGaN

Methodology Applied
Scientific EffectEpitaxy: Epitaxy

Data Source

PatentEP2519979B1Optoelectronic semiconductor chip having two intermediate layers based on algan
Publication Date: 2019.12.18 OSRAM OPTO SEMICON GMBH & CO OHG
  • EP2519979B1 patent drawingFigure 1~3
  • EP2519979B1 patent drawingFigure 4~6
  • EP2519979B1 patent drawingFigure 7A~8

AI summary

In at least one form of embodiment of the optoelectronic semiconductor chip (100), said chip comprises a semiconductor layer sequence (1) based on GaN, InGaN, AlGaN und/oder InAlGaN. The semiconductor layer sequence (1) contains a p-doped layer sequence (2), an n-doped layer sequence (4), and an active zone (3) between the p-doped layer sequence (2) and the n-doped layer sequence (4). The semiconductor layer sequence (1) comprises at least one intermediate layer (5) based on AlxGa1-xN, where 0 < x = 1. The intermediate layer (5) is on the same side of the active zone (3) as the n-doped layer sequence (4) and, in relation to liquids with low viscosity, has a specific chemical permeability lower than a specific chemical permeability of regions of the semiconductor layer sequence (1) that border the intermediate layer (5).