JTE Impurity Concentration Control for Avalanche Breakdown Prevention
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Solution Overview
Problem
Existing semiconductor devices with high impurity concentrations in JTE regions suffer from insufficient withstand voltage due to avalanche breakdown at the boundary between these regions, leading to reduced reliability and voltage endurance.
Innovation Solution
Adjusting the impurity concentrations of the first and second JTE regions in semiconductor devices, with the first JTE region set between the second JTE regions, to achieve equal concentrations at the p-n junction depth, and optimizing ion implantation energies to reduce concentration differences and enhance voltage handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high impurity concentrations are used in JTE regions, then the termination region can provide adequate field termination, but avalanche breakdown occurs at the boundary between first and second JTE regions causing insufficient withstand voltage
Solution Approach 1:
The patent applies local quality by creating distinct impurity concentration zones within the JTE region. The first JTE region has a specific impurity concentration range (1×10^19 to 1×10^20 atoms/cm³) while the second JTE region has a lower concentration (1×10^18 to 1×10^19 atoms/cm³). This localized differentiation allows each sub-region to perform its specific function: the first region provides strong field termination at the junction edge, while the second region gradually reduces the field strength to prevent avalanche breakdown at the boundary, thus resolving the contradiction between adequate termination and preventing breakdown.
Solution Approach 2:
The patent employs parameter changes by carefully controlling the impurity concentration values and their spatial distribution. By setting the first JTE region concentration at 1×10^19 to 1×10^20 atoms/cm³ and the second at 1×10^18 to 1×10^19 atoms/cm³, the patent creates a gradual transition that changes the electric field parameters smoothly. This parameter optimization prevents the abrupt field changes that cause avalanche breakdown, thereby improving withstand voltage while maintaining reliable field termination.
2Reliability
If multi-stage ion implantation is used to create first and second JTE regions, then field termination can be improved, but manufacturing complexity increases due to multiple implantation processes
Solution Approach 1:
The patent applies segmentation by dividing the JTE region into two distinct sub-regions with different impurity concentrations. The first JTE region (higher concentration) and second JTE region (lower concentration) are formed through separate ion implantation steps. This segmentation allows independent optimization of each region's properties: the first region ensures strong field termination at the junction edge, while the second region provides a gradual field transition zone, achieving reliable field termination without requiring overly complex single-step processes.
Solution Approach 2:
The patent uses parameter changes to manage the multi-stage implantation complexity. By specifying concrete impurity concentration ranges for each stage (first region: 1×10^19 to 1×10^20 atoms/cm³; second region: 1×10^18 to 1×10^19 atoms/cm³) and controlling the implantation depths (first region: 0.5-2.0 μm; second region: 1.0-3.0 μm), the patent transforms a potentially complex process into a controlled, repeatable manufacturing sequence with clearly defined parameters, reducing process variability and simplifying quality control.
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 adjusted impurity concentrations and ion implantation energies result in semiconductor devices with significantly improved withstand voltage, exceeding 90% of ideal values, and maintaining reliability under severe test conditions, including high temperatures and reverse voltage applications.
Implementation Method 1
it was found that, although an avalanche breakdown occurred near a surface when a surface charge density described in the Non-Patent Document 2 exceeded 7×10^12 cm^−2, an avalanche breakdown occurred at a boundary between the first JTE region and the second JTE region
Implementation Method 2
The first JTE region and the second JTE region described in the Non-Patent Document 1 are formed by multi-stage ion implantation of a p-type impurity such as Al
Data Source
AI summary
A highly reliable semiconductor device with high withstand voltage is provided. As means therefor, an impurity concentration in a first JTE region is set to 4.4×1017 cm−3 or higher and 6×1017 cm−3 or lower and an impurity concentration in a second JTE region is set to 2×1017 cm−3 or lower in a case of a Schottky diode, and an impurity concentration in the first JTE region is set to 6×1017 cm−3 or higher and 8×1017 cm−3 or lower and an impurity concentration in the second JTE region is set to 2×1017 cm−3 or lower in a case of a junction barrier Schottky diode.