SiC Epitaxial Layer Doping Profile for Precise FTIR Thickness Measurement
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Solution Overview
Problem
Existing methods for measuring the thickness of a silicon carbide epitaxial layer lack precision, which affects the accuracy of silicon carbide semiconductor device manufacturing.
Innovation Solution
A silicon carbide epitaxial substrate with specific n-type impurity concentration profiles in its boundary, buffer, and drift layers, allowing for precise measurement of the layer thickness using Fourier Transform Infrared Spectroscopy (FTIR) to determine growth conditions for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used for epitaxial layer thickness, then manufacturing process is simple, but measurement precision is insufficient
Solution Approach 1:
The patent applies parameter changes by establishing specific n-type impurity concentration ranges for different layers (boundary layer: 1×10^19 to 1×10^21 atoms/cm³, buffer layer: 1×10^17 to 1×10^19 atoms/cm³, drift layer: 1×10^15 to 1×10^17 atoms/cm³). These controlled parameter variations create distinct FTIR measurement signals that enable precise thickness measurement while maintaining manufacturability through standard epitaxial growth processes.
2Measurement precision
If impurity concentration is increased to improve measurement signals, then measurement precision improves, but semiconductor device performance deteriorates
Solution Approach 1:
The patent applies local quality by creating spatially varying impurity concentrations across different regions of the epitaxial layer. The boundary layer has high impurity concentration (1×10^19 to 1×10^21 atoms/cm³) for strong FTIR measurement signals, while the drift layer maintains low impurity concentration (1×10^15 to 1×10^17 atoms/cm³) for optimal semiconductor device performance. This localized differentiation resolves the contradiction between measurement precision and device reliability.
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
Enhances the precision of silicon carbide epitaxial layer thickness measurement, leading to more accurate manufacturing of silicon carbide semiconductor devices.
Implementation Method 1
measuring a thickness of an epitaxial layer using Fourier transform infrared spectroscopy
Data Source
AI summary
A silicon carbide epitaxial substrate includes a silicon carbide substrate and a silicon carbide epitaxial layer. The silicon carbide epitaxial layer is provided on the silicon carbide substrate. The silicon carbide epitaxial layer has a boundary layer, a buffer layer, and a drift layer. The boundary layer is provided on the silicon carbide substrate. The buffer layer is provided on the boundary layer. The drift layer is provided on the buffer layer. A concentration of an n type impurity in the buffer layer is 3×1018/cm3 or more. A concentration of an n type impurity in the boundary layer is higher than the concentration of the n type impurity in the buffer layer.