Silicon Carbide Epitaxial Substrate Nitrogen Control
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Solution Overview
Problem
Conventional silicon carbide epitaxial substrates face challenges in achieving low background nitrogen concentration and uniform in-plane nitrogen distribution, leading to surface quality issues and impaired semiconductor device performance, particularly for high breakdown voltage applications.
Innovation Solution
A silicon carbide epitaxial substrate with a surface roughness of 0.6 nm or less and a nitrogen concentration ratio of 15% or less within the silicon carbide epitaxial layer, achieved by using a silicon carbide growth device with members having a nitrogen concentration of 10 ppm or less, which reduces nitrogen emission during epitaxial growth, ensuring good surface quality and uniform nitrogen distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial growth is performed under predetermined growth condition to achieve good surface quality, then surface quality is improved, but nitrogen is likely to be captured in the silicon carbide epitaxial substrate causing large in-plane distribution of background concentration
Solution Approach 1:
The invention changes the chemical composition parameters of the growth chamber members by using silicon carbide material with controlled nitrogen concentration (10 ppm or less) instead of conventional carbon materials. This parameter change in material composition allows simultaneous achievement of good surface quality and uniform nitrogen distribution by reducing nitrogen emission during epitaxial growth while maintaining growth conditions that produce high-quality surfaces.
2Temperature
If conventional carbon materials are used for growth chamber members, then high heat resistance and inductive heating capability are achieved, but nitrogen emission during epitaxial growth causes high background concentration in the silicon carbide epitaxial layer
Solution Approach 1:
The invention changes the material composition from conventional carbon-based materials to silicon carbide with controlled nitrogen content. This parameter change maintains the high-temperature stability and heat resistance required for epitaxial growth while dramatically reducing nitrogen emission, achieving background nitrogen concentrations of 1×10^15 cm^-3 or less in the epitaxial layer.
Solution Approach 2:
The invention uses silicon carbide as a composite material that combines the desirable properties of carbon materials (heat resistance, inductive heating capability) with reduced nitrogen content. The silicon carbide material serves as both the structural component for the growth chamber and the source of reduced nitrogen emission, achieving a dual-function solution.
3Object-generated harmful factors
If nitrogen concentration in film member is reduced to 10 ppm or less, then background nitrogen concentration is sufficiently reduced, but manufacturing complexity increases due to stringent material control requirements
Solution Approach 1:
The invention establishes a clear target parameter for material composition (nitrogen concentration of 10 ppm or less in growth chamber members) that can be systematically controlled during manufacturing. By setting this specific parameter threshold, the complex requirement for low nitrogen emission is transformed into a measurable and controllable material specification that can be enforced through standard quality control procedures.
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 approach results in a silicon carbide epitaxial substrate with improved surface quality and high in-plane uniformity of nitrogen concentration, suitable for manufacturing semiconductor devices requiring high breakdown voltage with enhanced efficiency and reduced property fluctuations.
Implementation Method 1
a material capable of being inductively heated and having a high heat resistance is employed for members, such as a heat generator and a susceptor, that form a growth chamber
Implementation Method 2
Epitaxial growth of a compound semiconductor such as silicon carbide on a substrate needs to be performed by reacting a treatment gas (source material gas or the like) under a high temperature
Data Source
AI summary
A silicon carbide epitaxial substrate having a main surface (second main surface) includes: a base substrate; and a silicon carbide epitaxial layer formed on the base substrate and including the main surface (second main surface), the second main surface having a surface roughness of 0.6 nm or less, a ratio of standard deviation of a nitrogen concentration in the silicon carbide epitaxial layer at a surface layer including the main surface (second main surface) within a plane of the silicon carbide epitaxial substrate to an average value of the nitrogen concentration in the silicon carbide epitaxial layer at the surface layer within the plane of the silicon carbide epitaxial substrate being 15% or less.