Superjunction Semiconductor Oxygen Reduction
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Solution Overview
Problem
Semiconductor devices made from CZ-material suffer from high oxygen concentration, leading to oxygen precipitates and COPs that negatively impact charge carrier mobility, necessitating improved methods to reduce their influence.
Innovation Solution
A method involving thermal oxygen-out-diffusion anneal and thermal oxidation anneal to reduce oxygen concentration in semiconductor substrates, followed by epitaxial layer formation and superjunction structure creation, effectively lowering oxygen levels and defect density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CZ-semiconductor material is used due to cost reasons, then manufacturing cost is reduced, but oxygen concentration increases leading to oxygen precipitates and COPs that worsen charge carrier mobility
Solution Approach 1:
The patent applies preliminary action by performing a thermal annealing treatment on the CZ-semiconductor substrate before manufacturing the semiconductor device. This pre-treatment reduces the oxygen concentration in the substrate, preventing oxygen precipitates and COPs from forming during subsequent processing and device operation, thereby maintaining high charge carrier mobility while still using cost-effective CZ material
Solution Approach 2:
The patent changes the oxygen concentration parameter in the semiconductor substrate through thermal annealing. By heating the substrate to specific temperatures (e.g., 800-1200°C) in a controlled atmosphere, the oxygen distribution is modified, reducing oxygen precipitates and improving charge carrier mobility without changing the fundamental CZ material composition
2Reliability
If thermal annealing treatment is applied to reduce oxygen concentration, then charge carrier mobility is improved, but additional process steps and time are required
Solution Approach 1:
The patent merges the oxygen-reduction annealing step with other necessary thermal processing steps in the manufacturing flow. By combining multiple thermal treatments into integrated process sequences, the overall additional time required is minimized while still achieving the necessary oxygen concentration reduction for improved charge carrier mobility
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 enhances charge carrier mobility, reduces on-state resistance, and improves thermal conductivity by minimizing oxygen precipitates and COPs, resulting in improved semiconductor device performance.
Implementation Method 1
subjecting the semiconductor substrate to a thermal oxygen-out-diffusion anneal at a temperature sufficient to reduce the oxygen concentration in a surface region of the semiconductor substrate
Implementation Method 2
forming an epitaxial layer on the first side of the semiconductor substrate
Implementation Method 3
implanting dopants for forming a superjunction semiconductor device structure in the epitaxial layer
Implementation Method 4
subjecting the epitaxial layer to a thermal treatment at a temperature of at least 1050° C. to diffuse the dopants in the epitaxial layer
Data Source
AI summary
A semiconductor device includes: a semiconductor substrate having a bulk oxygen concentration of at least 6×1017 cm−3; an epitaxial layer on a first side of the semiconductor substrate, the epitaxial layer and the semiconductor substrate having a common interface; a superjunction semiconductor device structure in the epitaxial layer; and an interface region extending from the common interface into the semiconductor substrate to a depth of at least 10 μm. A mean oxygen concentration of the interface region is lower than the bulk oxygen concentration of the semiconductor substrate.