Power Semiconductor Device With Non-Uniform Gate Work Function
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Solution Overview
Problem
Conventional power semiconductor devices face a trade-off between minimizing on-state losses and decreasing short circuit current, with techniques to reduce short-circuit current often resulting in higher on-state losses and vice versa, limiting their application in high-reliability and efficiency requirements.
Innovation Solution
The implementation of a power semiconductor device with a non-uniform work function profile along the channel region, combined with non-uniform thickness and doping profiles, to locally adjust the threshold voltage, thereby reducing saturation and short-circuit currents without affecting on-state losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques are used to reduce short-circuit current, then short circuit capability is improved, but on-state losses increase
Solution Approach 1:
The gate electrode is divided into multiple sections along the channel region, with each section having a different work function. This creates local variations in threshold voltage along the channel, allowing the short-circuit current to be reduced in specific regions while maintaining low on-state losses in other regions. The non-uniform work function profile enables spatially selective control of carrier flow.
Solution Approach 2:
The work function of the gate electrode is changed from a uniform parameter to a non-uniform parameter that varies along the channel region. This parameter change allows independent optimization of different regions: sections with higher work function reduce short-circuit current, while sections with lower work function maintain low on-state resistance, thereby resolving the contradiction between short circuit capability and on-state losses.
2Ease of manufacture
If uniform threshold voltage is used, then manufacturing is simpler, but performance optimization is limited
Solution Approach 1:
The gate electrode is segmented into multiple sections along the channel region, with each section having a different work function. This segmentation allows independent optimization of electrical characteristics in different regions while maintaining a relatively simple overall structure. The segmented design can be implemented using standard fabrication techniques by forming the gate electrode in sections or using multiple deposition steps.
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 enhances short circuit capability while maintaining low on-state losses, allowing for independent optimization of other loss-reducing methods, thus improving the overall performance of power semiconductor devices.
Implementation Method 1
the gate electrode has a non-uniform work function profile along the channel region, such that a threshold voltage of the gate electrode is highest in a first section of the channel region remote from the source region
Data Source
Figure 1~3
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Figure 6~7
AI summary
In at least one embodiment, the power semiconductor device (1) comprises: - a semiconductor body (2) having a source region (21) of a first conductivity type and a well region (22) of a second conductivity type different from the first conductivity type, and the well region (22) comprises a channel region (220) starting directly at the source region (21), and - a gate insulator (4) directly between the semiconductor body (2) and a gate electrode (31), wherein the gate electrode (4) has a non-uniform work function profile (6) along the channel region (220), such that a threshold voltage (Vth) is highest in a first section (61) remote from the source region (21).