Semiconductor Trench Gate Termination Design
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Solution Overview
Problem
Power semiconductor devices face challenges in withstanding avalanche breakdown, particularly at termination portions where electric field concentrations occur, leading to potential device destruction during high-speed switching operations.
Innovation Solution
The semiconductor device design incorporates trench gates and strategically placed contact holes in the termination region with specific dimensions and arrangements to distribute electric field breakdowns, reducing contact resistance and enhancing avalanche withstand capability by ensuring uniform current discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown voltage at termination portions is increased to enhance avalanche withstand capability, then the device reliability improves, but the manufacturing complexity increases due to the need for precise control of contact hole dimensions and arrangements
Solution Approach 1:
The patent applies local quality by differentiating the contact hole structure between the cell region and termination region. Specifically, the termination region contact holes are designed with smaller opening areas compared to the cell region contact holes, creating locally optimized electric field distribution. This localized structural differentiation enhances avalanche withstand capability at the termination portions without requiring complete redesign of the entire device structure, thus improving reliability while controlling manufacturing complexity.
Solution Approach 2:
The patent segments the contact hole structure into distinct regions: cell region contact holes and termination region contact holes. This segmentation allows independent optimization of each region's electrical characteristics. The termination region contact holes are specifically designed with smaller openings and different arrangements to handle the unique electric field stress at termination portions, enabling targeted improvement of avalanche capability without uniformly complicating the entire device structure.
2Reliability
If contact holes in the termination region are designed with smaller opening areas to distribute electric field stress, then the breakdown voltage increases, but the contact resistance management becomes more difficult
Solution Approach 1:
The patent addresses the contact resistance challenge by transitioning from a two-dimensional opening area parameter to a three-dimensional structure. By forming raised portions (ridges) between adjacent contact holes in the termination region, the design utilizes the vertical dimension to increase the effective contact area and improve electrical connection. This dimensional transition allows smaller opening areas (for higher breakdown voltage) while compensating for potential contact resistance increases through the added vertical contact path via the raised portions.
Solution Approach 2:
The raised portions formed between adjacent contact holes act as intermediary structures that facilitate electrical connection. These raised portions serve as conductive bridges that mediate between the smaller contact hole openings and the underlying semiconductor layers, ensuring adequate electrical connectivity even when the contact hole openings are minimized for enhanced breakdown voltage. The intermediary raised portions effectively decouple the conflicting requirements of small openings and low contact resistance.
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 design effectively increases the breakdown voltage and avalanche withstand capability, particularly at corner portions, reducing the risk of device destruction by distributing electric field stress and minimizing contact resistance.
Implementation Method 1
there is a need for a semiconductor device with a high withstand capability for avalanche breakdown
Implementation Method 2
The first contact region contains an impurity of the second conductivity type ion implanted at a bottom of each of a plurality of first contact holes
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first and a second semiconductor layer of a first conductivity type, a third semiconductor layer of a second conductivity type, a source region of the first conductivity type, a first and a second main electrode, trench gates, a first and a second contact region. The third semiconductor layer is provided on the second semiconductor layer provided on the first semiconductor layer. The first main electrode is electrically connected to the first semiconductor layer. The second main electrode is electrically connected to the source region provided on the third semiconductor layer. The trench gates are provided from the third semiconductor layer to the second semiconductor layer. The first and second contact regions electrically connect the second main electrode and the third semiconductor layer. An opening area of the second contact hole is smaller than that of the first contact hole.