Semiconductor Edge-Termination Structure With Single-Step Sloped Depression
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Solution Overview
Problem
The existing manufacturing methods for electronic devices, such as Schottky diodes, face challenges in achieving a smooth edge transition region with a slope less than 90°, which is essential for preventing premature avalanche-multiplication and reducing reverse leakage current, while also minimizing the active area and avoiding misalignment issues due to the need for multiple etching masks and processes.
Innovation Solution
A method that forms trenches with substantially vertical walls and a depression region with a sloped surface in a single processing step, using a combination of photolithographic masking and etching techniques to achieve the desired slope without increasing the number of masks or manufacturing steps, thereby reducing costs and misalignment risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If anisotropic etching is used to form trenches with vertical side walls, then the device compactness is improved, but a steep step is formed between the edge transition region and edge termination region causing field concentration and premature avalanche-multiplication
Solution Approach 1:
The patent segments the edge termination region into multiple zones with different doping concentrations (first, second, and third doping regions) arranged in a gradient from the active area outward. This segmentation allows each zone to contribute differently to field distribution, preventing concentration at any single point while maintaining compact device geometry.
Solution Approach 2:
The patent applies local quality by creating spatially varying doping concentrations within the edge termination region. The first doping region has a first concentration, the second has a second concentration, and the third has a third concentration, with each local area optimized for its specific function in field distribution and breakdown voltage control.
2Manufacturing precision
If multiple etching masks and processes are used to form the desired slope, then the edge transition region with slope less than 90° is achieved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple doping steps into a unified process sequence where implantation masks are strategically positioned to create the multi-zone doping profile in a coordinated manner. The first, second, and third doping regions are formed through integrated masking and implantation steps rather than separate etching processes, reducing overall manufacturing complexity.
Solution Approach 2:
The patent employs preliminary action by using implantation masks that are positioned and configured before the actual doping process to pre-determine the doping profile. The masks are designed in advance to create the specific concentration gradients and spatial distribution of dopants, eliminating the need for subsequent corrective etching steps.
3Area of stationary object
If the active area is minimized, then the device size is reduced, but the field line concentration increases causing premature avalanche-multiplication
Solution Approach 1:
The patent introduces asymmetry in the doping concentration distribution around the active area. The edge termination region features an asymmetric gradient where doping concentrations vary differently in different directions and distances from the active area, creating an asymmetric field distribution that prevents concentration at specific points while maintaining compact active area dimensions.
Solution Approach 2:
The patent addresses field line concentration by introducing a doping concentration dimension rather than merely expanding the physical area. The multi-zone doping structure creates a third dimension of control (doping concentration) that allows field distribution optimization independent of the active area footprint, effectively managing field lines through compositional rather than geometric expansion.
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 allows for a more efficient and cost-effective production of electronic devices with reduced active area and minimized field line concentration, addressing the issues of premature avalanche-multiplication and reverse leakage current while maintaining electrical performance.
Implementation Method 1
forming a trench in the drift layer by etching the drift layer starting from the top surface; forming a depression region between said trench and said edge-termination structure by etching the drift layer starting from the top surface
Implementation Method 2
forming an edge-termination structure laterally to said trench by implanting dopant species which have a second conductivity different from the first conductivity
Data Source
AI summary
A manufacturing method of an electronic device includes: forming a drift layer of an N type; forming a trench in the drift layer; forming an edge-termination structure alongside the trench by implanting dopant species of a P type; and forming a depression region between the trench and the edge-termination structure by digging the drift layer. The steps of forming the depression region and the trench are carried out at the same time. The step of forming the depression region comprises patterning the drift layer to form a structural connection with the edge-termination structure having a first slope, and the step of forming the trench comprises etching the drift layer to define side walls of the trench, which have a second slope steeper than the first slope.