Nitride Semiconductor Growth on Ultrathin Silicon

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Solution Overview

Problem

The challenge in manufacturing high-quality nitride semiconductor crystal layers is the introduction of dislocations due to lattice mismatch and thermal expansion coefficient differences when grown on silicon substrates, leading to poor mass productivity and device performance.

Innovation Solution

A method involving the growth of a nitride semiconductor crystal layer on an ultrathin silicon crystal layer with a thickness of 50 nm or less, which is incorporated into the nitride semiconductor layer, reducing strain and dislocation density by interdiffusion of gallium and silicon atoms, and using an intermediate layer with a low thermal expansion coefficient to balance thermal contraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If nitride semiconductor crystal layer is grown on silicon substrate, then mass productivity is improved, but dislocation density increases due to lattice mismatch and thermal expansion coefficient differences

Engineering Contradiction:

Improvemass productivityVSAvoiddislocation density

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

An ultrathin silicon crystal layer (50 nm or less) is introduced as an intermediary between the silicon substrate and the nitride semiconductor crystal layer. This ultrathin layer serves as a mediator that reduces the lattice mismatch and thermal expansion coefficient differences, thereby lowering dislocation density while maintaining the benefits of silicon substrate growth for mass productivity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The thickness parameter of the silicon crystal layer is changed from conventional thick substrates to an ultrathin layer of 50 nm or less. This parameter change fundamentally alters the strain and dislocation characteristics, enabling low dislocation density in the nitride semiconductor layer while preserving silicon substrate advantages

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If ultrathin silicon crystal layer is used, then dislocation density is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improvedislocation densityVSAvoidmanufacturing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The ultrathin silicon crystal layer is designed to be self-incorporated into the nitride semiconductor crystal layer during the growth process. The silicon atoms from the ultrathin layer are automatically absorbed and integrated into the growing nitride semiconductor structure, eliminating the need for separate removal steps and simplifying the overall manufacturing process

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If silicon crystal layer thickness is reduced, then strain is reduced, but structural stability may be compromised

Engineering Contradiction:

ImprovestrainVSAvoidstructural stability

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The ultrathin silicon crystal layer is merged with the nitride semiconductor crystal layer through atomic interdiffusion during growth. The silicon atoms are incorporated into the nitride semiconductor structure, creating a combined structure that maintains structural stability while reducing strain, as the ultrathin silicon layer and nitride semiconductor layer become integrated at the atomic level

Inventive Principle:

Principle #5Merging (Combining)

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 approach results in a nitride semiconductor crystal layer with reduced dislocation density, improved crystallinity, and enhanced productivity, addressing the issues of lattice mismatch and thermal expansion coefficient differences, thereby producing high-quality nitride semiconductor devices.

Implementation Method 1

reducing strain and dislocation density by interdiffusion of gallium and silicon atoms

Methodology Applied

Scientific EffectInterdiffusion: Diffusion

Implementation Method 2

using an intermediate layer with a low thermal expansion coefficient to balance thermal contraction

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS8790999B2Method for manufacturing nitride semiconductor crystal layer

Publication Date: 2014.07.29 ALPAD CORP

AI summary

According to one embodiment, a method is disclosed for manufacturing a nitride semiconductor crystal layer. The method can include forming the nitride semiconductor crystal layer having a first thickness on a silicon crystal layer. The silicon crystal layer is provided on a base body. The silicon crystal layer has a second thickness before the forming the nitride semiconductor crystal layer. The second thickness is thinner than the first thickness. The forming the nitride semiconductor crystal layer includes making at least a portion of the silicon crystal layer incorporated into the nitride semiconductor crystal layer to reduce a thickness of the silicon crystal layer from the second thickness.