Oxygen-Related Thermal Donor Dopant Control in Semiconductor Wafers
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Solution Overview
Problem
The manufacturing of power semiconductor devices with high blocking capability is expensive due to the high growth rate of epitaxial layers, and existing methods for producing semiconductor wafers with high blocking voltages result in inhomogeneous dopant distribution and high costs.
Innovation Solution
A method that determines the extrinsic dopant and intrinsic oxygen concentrations in semiconductor wafers to generate or dissociate oxygen-related thermal donors, creating a process temperature gradient to achieve a target dopant concentration, thereby reducing costs and improving homogeneity without the need for epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial growth is used to produce drift zones with high dopant concentrations, then dopant distribution homogeneity is improved, but manufacturing cost increases and productivity decreases due to the high growth rate requirement
Solution Approach 1:
The patent changes the fundamental parameter of dopant introduction timing from during-growth (epitaxial) to post-growth (thermal processing). By applying thermal energy after epitaxial layer formation, oxygen-related thermal donors are generated in-situ, achieving the desired dopant concentration without requiring high-speed epitaxial growth processes.
Solution Approach 2:
The patent extracts the dopant introduction step from the epitaxial growth process itself. Instead of incorporating dopants during growth, the method separates this function by introducing oxygen through thermal processing after growth, thereby decoupling the homogeneity achievement from the expensive high-speed growth requirement.
2Reliability
If sawing from silicon ingots grown by localized molten zone is used for high blocking voltages, then blocking capability is improved, but dopant distribution homogeneity deteriorates
Solution Approach 1:
The patent applies preliminary thermal processing to generate oxygen-related thermal donors throughout the drift zone before final device fabrication. This preliminary action ensures uniform dopant distribution is established in advance, which then supports high blocking capability without relying on the inhomogeneous dopant distribution from molten zone ingots.
Solution Approach 2:
The patent introduces oxygen as an intermediary substance that, when subjected to thermal processing, forms oxygen-related thermal donors. This intermediary mechanism enables controlled dopant generation with superior homogeneity compared to direct dopant introduction methods.
3Productivity
If high growth rate epitaxial layers are used to reduce manufacturing time, then productivity is improved, but manufacturing precision and cost-effectiveness worsen due to the expensive process
Solution Approach 1:
The patent performs preliminary epitaxial growth at standard, cost-effective growth rates to form the drift zone structure. The expensive high-speed growth is avoided entirely, while the desired dopant concentration and homogeneity are achieved through subsequent thermal processing that generates oxygen-related thermal donors in-situ.
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 method allows for the efficient production of semiconductor devices with a dopant concentration ratio of at least 25% oxygen-related thermal donors, reducing production costs and achieving homogeneous dopant distribution across the wafer, enabling the manufacture of power semiconductor devices with high blocking voltages.
Implementation Method 1
a process temperature gradient for generating or dissociating oxygen-related thermal donors is determined to compensate for a difference between a target dopant concentration and the extrinsic dopant concentration
Data Source
AI summary
A method of manufacturing a semiconductor device includes determining information that indicates an extrinsic dopant concentration and an intrinsic oxygen concentration in a semiconductor wafer. On the basis of information about the extrinsic dopant concentration and the intrinsic oxygen concentration as well as information about a generation rate or a dissociation rate of oxygen-related thermal donors in the semiconductor wafer, a process temperature gradient is determined for generating or dissociating oxygen-related thermal donors to compensate for a difference between a target dopant concentration and the extrinsic dopant concentration.