Semiconductor Trench Structure Reducing Capacitance
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Solution Overview
Problem
Semiconductor devices with increased trench structures reduce ON resistance but also increase capacitance per unit area, leading to higher switching loss and energy consumption.
Innovation Solution
A semiconductor device structure with additional trenches between existing trenches, where field plate electrodes are replaced by an embedded insulating film, reducing capacitance while maintaining low ON resistance by forming current paths in channel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional trenches are formed in the semiconductor layer to reduce ON resistance, then the ON resistance decreases, but the capacitance per unit area increases leading to higher switching loss
Solution Approach 1:
The patent divides the trench structure into two types: first trenches containing field plate electrodes and gate electrodes, and second trenches containing only embedded insulating films. This segmentation allows the device to benefit from increased trench density for lower ON resistance while avoiding the capacitance penalty associated with adding more field plate electrodes, thereby reducing switching loss.
Solution Approach 2:
Different regions of the semiconductor device are assigned different functions: first trenches are designed with field plate electrodes and gate electrodes for voltage control and field management, while second trenches are designed with only embedded insulating films for capacitance reduction. This local differentiation optimizes both ON resistance and switching loss characteristics.
2Reliability
If field plate electrodes are added to increase breakdown withstand voltage, then the breakdown voltage is maintained, but the capacitance increases leading to higher energy consumption
Solution Approach 1:
The patent segments the voltage control function between field plate electrodes in first trenches and embedded insulating films in second trenches. The embedded insulating films in second trenches provide voltage blocking capability that maintains breakdown withstand voltage without the capacitance penalty of adding more field plate electrodes, thus reducing energy consumption.
Solution Approach 2:
The patent uses embedded insulating films in second trenches as a simpler, lower-capacitance alternative to field plate electrodes for providing voltage blocking capability. These embedded insulating films serve the necessary voltage control function without the overhead of complex electrode structures, reducing overall energy consumption.
3Reliability
If the semiconductor layer is enlarged to accommodate more trenches, then more current paths can be formed, but the device area increases
Solution Approach 1:
The patent segments the trench functions to maximize current path capacity within limited area: first trenches provide voltage control and field management, while second trenches provide additional current path separation and capacitance reduction. This functional segmentation allows more trenches to be packed into the same area without proportionally increasing device area.
Solution Approach 2:
The patent utilizes the vertical dimension by forming trenches that extend deep into the semiconductor layer, creating three-dimensional current paths. This vertical exploitation of space allows increased current path capacity without proportional increases in horizontal device area.
Data Source
AI summary
A semiconductor device including, a semiconductor layer including a plurality of first trenches formed therein and a second trench formed in a region between the first trenches, channel regions formed in regions between the first and second trenches in a surface layer portion of the semiconductor layer, field plate electrodes embedded at bottom portion sides of the respective first trenches, first gate electrodes embedded at opening portion sides of the respective first trenches so as to face the channel regions across first gate insulating films above the field plate electrodes, second insulating films interposed between the field plate electrodes and the first gate electrodes, an embedded insulating film embedded to an intermediate portion of the second trench, and a second gate electrode embedded in the second trench so as to face the channel regions across a second gate insulating film above the embedded insulating film.