Semiconductor Device Current Distribution via Variable Cell Drive
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Solution Overview
Problem
In semiconductor devices used for driving inductive loads in ignition systems, uneven current distribution across the device plane leads to a trade-off between current drive capability and breakdown resistance, restricting device size and cost.
Innovation Solution
A semiconductor device with a transistor cell region where multiple regions have varying current drive capabilities based on distance from the electrode pad, ensuring even current distribution by distributing high current shares into surrounding regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform IGBT cell layout is adopted across the semiconductor device plane, then the device structure is simple and easy to manufacture, but current density becomes uneven with high current concentration in certain regions, limiting breakdown resistance
Solution Approach 1:
The patent applies local quality by dividing the semiconductor device into multiple regions with different current drive capabilities. Regions closer to the emitter pad have lower current drive capability while regions farther away have higher current drive capability. This non-uniform distribution matches the natural current flow patterns and eliminates local current concentration, thereby improving breakdown resistance without significantly complicating the manufacturing process.
2Area of stationary object
If the chip area is reduced to lower cost, then the device size and cost are restricted, but current drive capability must be maintained
Solution Approach 1:
The patent changes the parameter of current drive capability across different regions of the semiconductor device. By adjusting the current drive capability parameter spatially - lower near the emitter pad and higher farther away - the device can utilize the entire chip area more effectively. This allows maintaining high total current drive capability while using a smaller chip area, as the current distribution is optimized to avoid wasted capacity in low-current regions.
3Power
If IGBT cells are disposed near the emitter pad to increase current drive capability, then current load becomes larger in that region, but transient carrier concentration variation causes low current density and potential breakdown starting points in intermediate regions
Solution Approach 1:
The patent applies preliminary action by pre-designing the current drive capability distribution to anticipate and prevent current concentration problems. Instead of allowing current to naturally concentrate in intermediate regions during operation, the device structure is designed in advance with varying current drive capabilities across regions. This preliminary structural arrangement ensures that current density remains balanced throughout the device, preventing breakdown before it can occur during transient operations.
Data Source
AI summary
An object of the present invention is to provide a semiconductor device capable of eliminating unevenness of current distribution in a plane. A semiconductor device according to the present invention is a semiconductor device including a transistor cell region where a plurality of transistor cells is arranged on a semiconductor substrate, the semiconductor device including an electrode pad which is arranged avoiding the transistor cell region on the semiconductor substrate and is electrically connected to a one-side current electrode of each of the cells, in which the transistor cell region contains a plurality of regions each of which has a different current drive capability from each other depending on a distance from the electrode pad.