Segmented Field Plate Termination for High Voltage IGBTs
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Solution Overview
Problem
Semiconductor devices, particularly insulated gate bipolar transistors (IGBTs), face challenges in achieving high breakdown voltage due to steep potential gradients in the termination regions, which can lead to disconnection of field plate films and limitations in material selection.
Innovation Solution
The semiconductor device incorporates a termination structure with multiple field plate electrodes at increasing distances from the surface, connected to both the emitter potential and floating potentials, moderating the potential gradient and expanding the depletion layer into termination regions, thereby enhancing breakdown voltage without thickening the field plate film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single thick field plate film is used to increase breakdown voltage, then breakdown voltage is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The field plate structure is divided into multiple segments (first field plate electrode, second field plate electrode, third field plate electrode) positioned at different distances from the semiconductor surface. Each segment contributes to the overall breakdown voltage through its own depletion layer, achieving high breakdown voltage without requiring a single thick film that would be complex to manufacture.
Solution Approach 2:
Instead of increasing breakdown voltage by thickening the field plate film in the vertical dimension, the patent uses multiple field plate electrodes at different vertical positions (z-dimension) and horizontal positions (x-y plane). This multi-dimensional arrangement creates overlapping depletion layers that collectively achieve the desired breakdown voltage with thinner individual films.
2Reliability
If a single thick field plate film is used to increase breakdown voltage, then breakdown voltage is improved, but manufacturing precision requirements increase due to disconnection risks
Solution Approach 1:
The field plate is segmented into multiple electrodes that can be manufactured separately and connected through conductive structures. This segmentation reduces the risk of disconnection in any single film, as the multi-layer structure provides redundant conduction paths. Each field plate electrode can be formed and connected independently, lowering the overall manufacturing precision requirements compared to a single continuous thick film.
Solution Approach 2:
Different regions of the field plate structure have different properties: the first field plate electrode is positioned closest to the surface with specific doping, the second electrode is at an intermediate position, and the third electrode is farthest away. This local differentiation allows each segment to be optimized for its specific function and manufactured with appropriate precision requirements for that region.
3Reliability
If conventional termination structures are used, then breakdown voltage is limited, but device complexity remains low
Solution Approach 1:
The termination structure uses segmented field plate electrodes at different positions rather than a single conventional termination layer. This segmentation creates multiple depletion regions that collectively achieve higher breakdown voltage, justifying the increased structural complexity through superior electrical performance.
Solution Approach 2:
The termination structure combines multiple semiconductor regions with different doping types and concentrations (first conductivity type drift region, second conductivity type regions, third conductivity type regions) along with insulating layers and conductive field plate electrodes. This composite structure achieves breakdown voltages that cannot be obtained with conventional single-material termination structures.
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 configuration allows for increased breakdown voltage while reducing the thickness of the field plate film and expanding material selection options, preventing disconnection and improving the overall device performance.
Implementation Method 1
expanding the depletion layer into termination regions, thereby enhancing breakdown voltage
Data Source
AI summary
A semiconductor device includes a first semiconductor region of a first conductivity type, a second semiconductor region having a second conductivity type, a first insulating layer on the first and second semiconductor regions, and field plate electrodes are provided in the first insulating layer at different distances from the first semiconductor layer. A first field plate electrode is at a first distance, a second field plate electrode is at a second distance greater than the first distance, and a third field plate electrode is at a distance greater than the second distance. The first through third field plate electrodes are electrically connected to each other and the third electrode is electrically connected to the second semiconductor region.