Trench Gate Insulator Layout for Fast and Reliable Power Semiconductors
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Solution Overview
Problem
Power semiconductor devices, such as IGBTs, face challenges in achieving optimal switching operations due to the influence of gate resistance, which affects switching speed and reliability, and require a design that balances gate resistance with minimal area consumption for a high power/area ratio.
Innovation Solution
The design incorporates a power semiconductor device with a semiconductor body and an active region surrounded by an edge termination region, featuring first and second trenches with specific trench insulator thickness and breakdown voltage ratios to optimize gate resistance and reliability, including a second trench insulator that is at least 120% thicker than the first trench insulator, enhancing breakdown voltage and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gate resistance is reduced to improve switching speed, then the switching operations are improved, but the device reliability deteriorates
Solution Approach 1:
The gate resistance is segmented into multiple resistive elements distributed across first and second regions with different trench insulator thicknesses. This segmentation allows different parts of the gate structure to contribute differently to switching performance and reliability, with thinner insulators providing lower resistance for switching speed and thicker insulators providing higher breakdown voltage for reliability.
Solution Approach 2:
Different regions of the gate structure are assigned different insulator thicknesses to optimize local functions. The first region has thinner insulators (50-150 nm) for low resistance and fast switching, while the second region has thicker insulators (150-300 nm) for high breakdown voltage and reliability. This local differentiation resolves the contradiction between switching speed and reliability.
2Speed
If the gate resistance is reduced to improve switching operations, then the switching characteristics are improved, but the area consumption increases
Solution Approach 1:
The gate structure is segmented into first and second regions with different insulator thicknesses, allowing the resistive function to be distributed across multiple elements rather than requiring a single large resistor. This segmentation achieves the desired switching characteristics with more efficient area utilization.
Solution Approach 2:
The insulator thickness parameter is varied across different regions to optimize the resistance characteristics. By changing the thickness parameter from 50-150 nm in the first region to 150-300 nm in the second region, the patent achieves optimal switching characteristics without proportionally increasing area consumption.
3Reliability
If the trench insulator thickness is increased to improve breakdown voltage, then the device reliability is improved, but the gate resistance increases
Solution Approach 1:
The gate insulator system is segmented into first and second trenches with different insulator thicknesses. The first trenches have thinner insulators (50-150 nm) providing low resistance, while the second trenches have thicker insulators (150-300 nm) providing high breakdown voltage. This segmentation allows both low resistance and high breakdown voltage to coexist in the overall gate structure.
Solution Approach 2:
Different local regions of the gate structure are assigned different insulator thicknesses to optimize local functions. The thinner insulators in the first region provide low resistance for fast switching, while the thicker insulators in the second region provide high breakdown voltage for reliability, resolving the contradiction between these two parameters.
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 improves switching characteristics and reliability by providing a specific internal gate resistor that balances switching speed and power/area ratio, ensuring efficient control of load current while maintaining device reliability.
Implementation Method 1
a first trench insulator electrically isolating the first trench electrode from the semiconductor body; a second trench insulator electrically insulating the second trench electrode from the semiconductor body
Implementation Method 2
a minimal breakdown voltage of each second trench insulator amounts to at least 120% of a minimal breakdown voltage of each first trench insulator
Data Source
AI summary
A power semiconductor device includes a first region in an active region of a semiconductor body and including first trenches each having a first trench electrode electrically connected to a gate terminal and a first trench insulator. A second region includes second trenches each having a second trench electrode electrically connected to the gate terminal and a second trench insulator. At least one of the following applies: a minimal thickness of each second trench insulator amounts to at least 120% of a corresponding minimal thickness of each first trench insulator; an average thickness of the second trench insulators amounts to at least 120% of an average thickness of the first trench insulators; a trench bottom thickness of each second trench insulator amounts to at least 120% of a corresponding trench bottom thickness of each first trench insulator; a minimal breakdown voltage of each second trench insulator amounts to at least 120% of a minimal breakdown voltage of each first trench insulator.