Superjunction Trenches With Barrier Layer
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Solution Overview
Problem
Conventional trench approaches in superjunction device manufacturing result in significant fluctuations in device parameters due to interdiffusion of dopants, leading to increased on-state resistance and manufacturing complexity, which complicates cost reduction efforts.
Innovation Solution
The method involves forming alternating first and second trenches in a semiconductor layer using a trench etch mask, with differentiator masks ensuring precise formation of first and second semiconductor regions of opposite conductivity types, reducing interdiffusion and maintaining dopant concentration gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dopant diffusion is allowed to occur naturally during manufacturing, then manufacturing process is simpler, but on-state resistance increases due to reduced charge carrier mobility
Solution Approach 1:
The patent applies preliminary action by forming a barrier layer at the trench bottom before depositing the oppositely doped semiconductor material. This barrier layer prevents interdiffusion of dopants between adjacent n-type and p-type regions, maintaining sharp dopant concentration gradients and ensuring low on-state resistance while still allowing a relatively simple manufacturing process
Solution Approach 2:
The barrier layer acts as an intermediary element between the n-type and p-type semiconductor regions. It physically separates the two regions and prevents direct contact between oppositely doped materials, thereby eliminating dopant interdiffusion and maintaining high charge carrier mobility in the device
2Manufacturing precision
If high doping concentrations are used in semiconductor regions, then on-state resistance is reduced, but manufacturing complexity increases due to need for precise parameter control
Solution Approach 1:
The barrier layer is formed in advance at the trench bottom before depositing the oppositely doped semiconductor materials. This preliminary structure ensures that even with high doping concentrations, dopant interdiffusion is prevented, allowing precise dopant concentration control without requiring complex manufacturing processes
Solution Approach 2:
The patent changes the physical and chemical parameters of the barrier layer (material composition, thickness, doping type) to optimize its ability to prevent dopant interdiffusion. By adjusting these parameters, the device achieves low on-state resistance with high doping concentrations while maintaining manufacturing simplicity
3Ease of manufacture
If conventional trench filling approach is used, then manufacturing cost is reduced, but device parameters show significant fluctuations due to interdiffusion effects
Solution Approach 1:
The barrier layer is formed at the trench bottom before filling with oppositely doped semiconductor materials. This preliminary structure prevents dopant interdiffusion during subsequent manufacturing steps, ensuring consistent device parameters while maintaining the cost-effectiveness of the trench filling approach
Solution Approach 2:
The barrier layer serves as an intermediary that physically separates adjacent n-type and p-type regions throughout the manufacturing process. This separation prevents dopant interdiffusion and ensures reliable, consistent device parameters while allowing the use of simple and cost-effective manufacturing techniques
Data Source
AI summary
A trench etch mask is formed on a process surface of a semiconductor layer. By using the trench etch mask, both first trenches and second trenches are formed that extend from the process surface into the semiconductor layer. The first and second trenches alternate along at least one horizontal direction parallel to the process surface. First semiconductor regions of a first conductivity type are formed in the first trenches. Second semiconductor regions of a second, opposite conductivity type are formed in the second trenches.