Growth-Inhibited Nitride Semiconductor Substrates for Off-Angle Uniformity

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Solution Overview

Problem

Existing methods for manufacturing nitride semiconductor substrates face challenges in achieving low dislocation density and uniform off-angle, leading to issues such as reduced productivity, deteriorated surface morphology, and uneven light emission in semiconductor devices.

Innovation Solution

A method involving a base substrate with a growth inhibition layer promoting three-dimensional growth, epitaxially growing a first layer with inclined interfaces, and then a second layer to achieve a mirror surface with controlled off-angle and reduced dislocation density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a crystal layer is grown on a base substrate using conventional epitaxial growth, then a nitride semiconductor substrate can be obtained, but the substrate exhibits high dislocation density and non-uniform off-angle

Engineering Contradiction:

Improvecrystal qualityVSAvoiddislocation density

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention divides the growth process into two distinct stages: first growing a layer with inclined interfaces to redirect dislocations, then growing a final layer with a flat (0001) surface. This segmentation allows each stage to serve a specific function in controlling dislocation density and achieving uniform off-angle.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces inclined interfaces (non-(0001) planes) as an intermediate dimensional feature between the base substrate and the final flat surface. These inclined interfaces serve as dislocation sinks, capturing and redirecting dislocations away from the growth direction, thereby reducing dislocation density in the final substrate.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional epitaxial growth is used to obtain a nitride semiconductor substrate, then substrate production is achieved, but productivity is reduced due to the need for additional processing steps

Engineering Contradiction:

Improvesubstrate production efficiencyVSAvoidgrowth process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The invention performs both the inclined interface growth and the final flat surface growth in a continuous epitaxial process without removing the substrate or changing growth conditions dramatically. This continuous process reduces manufacturing steps and improves productivity while achieving the desired crystal quality.

Inventive Principle:

Principle #20Continuity of useful action

3Shape

If a flat (0001) surface is maintained throughout growth, then surface morphology is simple, but off-angle variation is non-uniform and crystal quality deteriorates

Engineering Contradiction:

Improvesurface morphologyVSAvoidoff-angle uniformity

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The invention temporarily introduces asymmetric inclined interfaces during the growth process. These asymmetric features serve to redirect dislocations and control the growth front, ultimately leading to a more uniform off-angle distribution in the final flat (0001) surface.

Inventive Principle:

Principle #4Asymmetry

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

Improves crystal quality by reducing dislocation density and off-angle variation, enhancing the performance and reliability of semiconductor devices.

Implementation Method 1

a first step of growing a first layer by epitaxially growing a single crystal of a group III nitride semiconductor on the main surface of the base substrate via openings in the growth inhibition layer

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Implementation Method 2

performing in situ formation of a growth inhibition layer in a vapor phase growth apparatus

Methodology Applied

Scientific EffectVapor phase deposition: Physical Vapour Deposition

Data Source

PatentUS12435441B2Method for manufacturing nitride semiconductor substrate, nitride semiconductor substrate, and laminate structure

Publication Date: 2025.10.07 SUMITOMO CHEM CO LTD

AI summary

A step of preparing a base substrate of a single crystal of a group III nitride semiconductor; a growth inhibition layer forming step of performing in situ formation of a growth inhibition layer over the entire main surface of the base substrate in a vapor phase growth apparatus; a first step of growing a first layer by epitaxially growing a single crystal of a group III nitride semiconductor on the main surface of the base substrate via openings in the growth inhibition layer by using the vapor phase growth apparatus where the base substrate on which the growth inhibition layer has been formed is placed in the vapor phase growth apparatus; and a second step of growing a second layer with a mirror surface by epitaxially growing a single crystal of a group III nitride semiconductor on the first layer so as to make the inclined interfaces disappear.