SiC MOS Device Current Detection Region Area Ratio
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face reliability issues due to decreased adhesion between the front electrode and bonding wire or external terminal electrode at high temperatures, leading to potential destruction of the current sensing region during reverse recovery, especially when the arithmetic area of contact between the current detecting electrode and source region is larger than that with the base region.
Innovation Solution
A semiconductor device with a metal oxide semiconductor (MOS) structure featuring a current detecting region and active region, where the arithmetic area of the second surface of the second semiconductor layer in the current detecting region is at most half that of the active region, and trenches with gate electrodes penetrating through the first and second semiconductor layers, reducing the effective arithmetic area and enhancing adhesion and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the arithmetic area of contact between the current detecting electrode and source region is made larger to improve current detection capability, then the detection sensitivity is improved, but the adhesion between the electrode and substrate decreases at high temperatures leading to reliability issues
Solution Approach 1:
The patent applies local quality by creating different contact area ratios in different regions of the semiconductor device. Specifically, the current detecting region has a smaller arithmetic area of the second semiconductor layer compared to the active region, resulting in a contact area ratio between the current detecting electrode and source region that is at most 1/2 that of conventional designs. This localized modification improves adhesion at high temperatures while maintaining sufficient current detection capability through the optimized electrode structure and positioning.
2Speed
If silicon carbide is used to enable high-temperature operation and high-speed switching, then the switching frequency can be increased ten times compared to silicon devices, but the adhesion between bonding wire and front electrode decreases at temperatures of at least 200 degrees C.
Solution Approach 1:
The patent applies parameter changes by modifying the arithmetic area parameter of the second semiconductor layer in the current detecting region. By reducing this area to at most half of that in the active region, the contact area ratio between the current detecting electrode and source region is optimized. This parameter modification changes the electrical and thermal characteristics locally, improving adhesion stability at high temperatures while preserving the high-speed switching capabilities enabled by silicon carbide.
3Reliability
If a pin-shaped external terminal electrode bonded by solder is used instead of bonding wire, then adhesion decreases at high temperatures are prevented, but the device complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting the problematic bonding wire connection from the current detecting region and replacing it with a simplified electrode structure. The current detecting electrode is designed with an optimized arithmetic area of the second semiconductor layer, eliminating the need for complex pin-shaped external terminal electrodes while maintaining reliable adhesion at high temperatures. This extraction simplifies the overall device structure while solving the adhesion problem.
Data Source
AI summary
A semiconductor device having a metal oxide semiconductor that includes a semiconductor substrate, a first semiconductor layer provided on a the semiconductor substrate, a plurality of second semiconductor layers selectively provided on the first semiconductor layer, a plurality of first semiconductor regions selectively provided in the second semiconductor layers at a surface thereof, a plurality of gate insulating films with a plurality of gate electrodes provided thereon, a plurality of first electrodes provided on the second semiconductor layers and the first semiconductor regions, and a second electrode provided on a back surface of the semiconductor substrate. The MOS structure configures an active region and a current detecting region of the semiconductor device. The semiconductor substrate and the first semiconductor layer are in both the active region and the current detecting region. Two of the second semiconductor layers, respectively in the current detecting region and the active region, are separated from each other by a predetermined distance.