Super Junction Power Structure Without Deep Trench Etching
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Solution Overview
Problem
Current super junction power devices face issues with stress, defects, and uniformity due to deep trench etching processes, leading to high costs and reduced reliability, while traditional epitaxial and implantation methods are complex and costly.
Innovation Solution
A super junction power device structure comprising an epitaxial layer, wells, trench gate structures, floating islands, and pillars of specific conductive types, where impurities are implanted directly to form these features without deep trench etching, simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep trench etching and filling process is used to form super junction, then breakdown voltage is improved, but stress and defects increase leading to reduced reliability
Solution Approach 1:
The patent extracts and eliminates the deep trench etching process from the super junction formation methodology. Instead of using deep trench etching and filling, the invention employs a simplified implantation process that directly forms the super junction structure without creating the harmful stress and defects associated with deep trench processing.
Solution Approach 2:
The patent replaces the mechanical deep trench etching and filling system with an implantation-based system. This substitution eliminates the mechanical stress and defects caused by deep trench processing while maintaining the electrical performance benefits of super junction structure.
2Reliability
If deep trench etching is used to form super junction, then breakdown voltage increases, but manufacturing complexity and cost increase
Solution Approach 1:
The patent removes the complex deep trench etching and filling steps from the manufacturing process. The simplified implantation-based approach directly creates the super junction structure, significantly reducing process complexity and manufacturing cost while maintaining high breakdown voltage performance.
Solution Approach 2:
Instead of following the conventional approach of etching deep trenches and then filling them to form super junction, the patent inverts the methodology by directly implanting dopants to form the super junction structure, eliminating the need for deep trench processing entirely.
3Reliability
If multiple epitaxial and implantation processes are used to form super junction, then breakdown voltage is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent merges multiple separate epitaxial and implantation processes into a single integrated implantation step. This consolidation achieves the same breakdown voltage enhancement while significantly reducing manufacturing cost and process complexity by eliminating redundant processing steps.
Solution Approach 2:
The patent performs the super junction formation through preliminary implantation action during the manufacturing process, establishing the required dopant distribution in advance. This preliminary action eliminates the need for subsequent complex epitaxial growth and multiple implantation steps, reducing overall manufacturing cost.
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 breakdown voltage, decreases capacitance, and lowers on-state resistance, improving yield and reliability while maintaining high doping concentrations for efficient current conduction.
Implementation Method 1
increase BV due to charge sharing effect
Implementation Method 2
implantation of doping in the epitaxial layer
Data Source
AI summary
The present invention provides a power device with super junction structure (or referred to as super junction power device). When making a super junction power device, impurity of a second conductive type may be implanted into an epitaxial layer of a first conductive type to form a floating island of the second conductive type and a pillar of the second conductive type successively through a super junction mask (or reticle) after forming the epitaxial layer of the first conductive type, directly through a well mask (or reticle) before or after forming a well of the second conductive type, and directly through a contact mask (or reticle) before or after forming a contact structure. Multiple epitaxial processes and deep trench etching process may not be needed. Therefore, the process is simple, the cost is low and yield and reliability are high. Because the super junction power device of the present invention has both the floating island of the second conductive type and the pillar of the second conductive type, in open state, a breakdown voltage may be raised and both Miller capacitance and input capacitance can be decreased and in on state, an on-state resistance can be decreased.