Trench Semiconductor Device With Isolated P-Type Layer
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Solution Overview
Problem
Power semiconductor devices face challenges in achieving high breakdown voltage and low leak current during switching operations, as existing designs often compromise on one or both due to limitations in trench structure and impurity concentration.
Innovation Solution
The semiconductor device incorporates a trench structure with a p-type semiconductor layer electrically isolated from the semiconductor part by an insulating film, facilitating extended depletion regions and reducing electric field strength at the Schottky Junction, thereby enhancing breakdown voltage and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impurity concentration is increased to reduce on-resistance, then conductivity improves, but breakdown voltage decreases
Solution Approach 1:
The semiconductor device is divided into multiple regions with different impurity concentrations: a first semiconductor layer with first impurity concentration and a second semiconductor layer with second impurity concentration. This segmentation allows each layer to optimize for its specific function - the first layer for breakdown voltage and the second layer for conductivity, thereby resolving the contradiction between high breakdown voltage and low on-resistance
Solution Approach 2:
Different regions of the semiconductor device are assigned different local properties - the first semiconductor layer has lower impurity concentration optimized for high breakdown voltage, while the second semiconductor layer has higher impurity concentration optimized for low on-resistance. This local quality differentiation enables simultaneous achievement of both high breakdown voltage and low on-resistance characteristics
2Ease of manufacture
If trench structure is simplified for ease of manufacture, then manufacturing cost decreases, but breakdown voltage and leak current performance deteriorate
Solution Approach 1:
The trench structure is segmented into multiple functional zones: a first trench region and a second trench region with different impurity concentrations. This segmentation allows the structure to achieve complex electrical characteristics while maintaining a relatively simple overall trench geometry that is feasible to manufacture, thus balancing manufacturing ease with high breakdown voltage performance
Solution Approach 2:
The invention changes the impurity concentration parameter within the trench structure - creating regions with different doping levels. This parameter variation enables the trench to provide both mechanical support and optimized electrical fields for high breakdown voltage, while the overall trench structure remains simple enough for practical manufacturing
3Reliability
If breakdown voltage is increased for high voltage operation, then voltage handling capability improves, but leakage current increases
Solution Approach 1:
The semiconductor device segments the current path into different regions with different impurity concentrations. The first semiconductor layer with lower impurity concentration handles the high voltage breakdown, while the second semiconductor layer with higher impurity concentration provides a low-leakage current path, thereby achieving high breakdown voltage with minimized leakage current
Solution Approach 2:
Different local regions are optimized for different functions: the first semiconductor layer has properties optimized for high breakdown voltage with lower impurity concentration, while the second semiconductor layer has properties optimized for low leakage current with higher impurity concentration. This local quality optimization resolves the contradiction between high breakdown voltage and low leakage current
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 impurity concentration without compromising breakdown voltage, reducing on-resistance and leakage current, leading to improved power efficiency and reduced power consumption.
Implementation Method 1
an insulating film electrically isolating the first semiconductor layer from the semiconductor part
Implementation Method 2
The second electrode contacts the semiconductor part with a rectification property
Implementation Method 3
facilitating extended depletion regions and reducing electric field strength at the Schottky Junction, thereby enhancing breakdown voltage
Data Source
AI summary
A semiconductor device includes a semiconductor part of a first conductivity type, a trench being provided in the semiconductor part at a front surface side; a first electrode provided on a back surface of the semiconductor part; a second electrode provided on the front surface of the semiconductor part; a first semiconductor layer of a second conductivity type provided inside the trench; and a insulating film electrically isolating the first semiconductor layer from the semiconductor part. The second electrode is electrically connected to the semiconductor part and the first semiconductor layer. The second electrode contacts the semiconductor part with a rectification property.