Nitride Edge-Termination Structure for Higher Breakdown Voltage
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Solution Overview
Problem
Existing nitride semiconductor devices face challenges in achieving high breakdown voltage due to electric field concentration at the edge of the active region, which is exacerbated by high ion-implantation energy causing defects and high-temperature activation damaging the nitride surfaces, and complex etching processes leading to increased costs.
Innovation Solution
A self-edge termination structure is implemented using a nitride semiconductor device with guard rings and an impurity region, along with inclined planes, to reduce electric field concentration and prevent avalanche breakdown, while avoiding high-energy ion-implantation and high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high ion-implantation energy is used to optimize junction edge termination, then breakdown voltage is improved, but significant defects are introduced into nitride materials
Solution Approach 1:
The patent changes the energy parameter of ion implantation from high energy to low energy (e.g., 50 keV instead of MeV range), which fundamentally alters the implantation mechanism to avoid displacement damage and defect formation while still achieving effective junction termination and breakdown voltage improvement
2Reliability
If heat treatment at 1300°C or greater is applied to activate implanted ions, then ion activation is achieved, but nitride surfaces are damaged
Solution Approach 1:
The patent changes the temperature parameter from high temperature (1300°C or greater) to low temperature (below 1000°C, preferably 700-900°C), which is achieved through low-energy ion implantation that does not require high-temperature activation, thereby preserving nitride surface integrity
Solution Approach 2:
The patent replaces the thermal activation mechanism (high-temperature heat treatment) with a low-energy ion implantation mechanism that achieves ion activation through direct low-damage implantation, eliminating the need for damaging high-temperature processing
3Reliability
If complex etching processes are used to form junction termination regions, then breakdown voltage is improved, but process costs increase
Solution Approach 1:
The patent extracts and eliminates the complex multi-step etching process entirely, replacing it with a direct low-energy ion implantation approach that forms the junction termination region without requiring selective etching, pattern transfer, or multiple process steps
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
The self-edge termination structure enhances breakdown voltage by reducing peak electric fields by up to 68%, mitigates surface damage, and lowers process costs by eliminating high-energy ion-implantation and high-temperature activation steps.
Implementation Method 1
electric fields concentrate at an edge of an active region, and this field concentration initiates avalanche breakdown
Implementation Method 2
this field concentration initiates avalanche breakdown, determining the breakdown voltage of the semiconductor devices
Data Source
AI summary
Provided is a nitride semiconductor device including a nitride substrate of a first conductive type including an device region and a peripheral region, a first nitride layer of the first conductive type disposed on the nitride substrate, a second nitride layer of a second conductive type disposed on the first nitride layer in the device region, guard rings disposed on the first nitride layer in the peripheral region, and an impurity region of the second conductive type adjacent to each of the guard rings in the second nitride layer, wherein an upper surface of the first nitride layer is located at a higher level in the device region than in the peripheral region.