Semiconductor Device Asymmetric N-Type Region Latch-Up Prevention
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Solution Overview
Problem
In semiconductor devices with switching transistors connected to inductive loads, return currents can cause latch-up due to parasitic thyristor operation, potentially damaging the transistor, especially when current flows to the substrate increases.
Innovation Solution
A semiconductor device design with a semiconductor substrate featuring specific impurity regions and electrode configurations, including n-type and p-type regions, source, drain, and gate electrodes, where the distance between certain n-type regions and source electrodes is less than between those regions and drain electrodes, preventing current draw from the p-type region and thus avoiding latch-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between transistors is increased or dummy regions are added to prevent latch-up, then reliability improves, but chip area increases
Solution Approach 1:
The patent applies local quality by creating an asymmetric distance relationship between the first n-type region and the source/drain electrodes. Specifically, the distance from the first n-type region to the source electrode is made smaller than the distance to the drain electrode. This local asymmetry in geometric configuration creates an electric field distribution that directs return current through the parasitic npn transistor rather than through the p-type region, thereby preventing latch-up without requiring increased transistor spacing or additional dummy regions.
Solution Approach 2:
The patent changes the geometric parameters of the device structure by establishing specific distance relationships between the first n-type region and the source/drain electrodes. By controlling the relative distances (making the distance to source electrode smaller than to drain electrode), the patent modifies the electric field distribution and current flow paths. This parameter change enables the return current to be directed through the parasitic npn transistor, achieving latch-up prevention while maintaining compact chip area.
2Device complexity
If return current flows through the p-type region, then the device structure remains simple, but latch-up occurs due to parasitic thyristor operation
Solution Approach 1:
The patent introduces a local quality asymmetry in the geometric configuration between the first n-type region and the source/drain electrodes. The distance from the first n-type region to the source electrode is deliberately made smaller than the distance to the drain electrode. This creates an asymmetric electric field distribution that redirects the return current path through the parasitic npn transistor rather than through the p-type region, thereby preventing parasitic thyristor operation and latch-up while maintaining overall device structure simplicity.
Solution Approach 2:
The patent uses the parasitic npn transistor as an intermediary element to redirect the return current path. By configuring the first n-type region at an asymmetric position relative to the source and drain electrodes, the return current is channeled through the parasitic npn transistor structure. This intermediary path prevents the current from flowing through the p-type region and activating the parasitic thyristor, thus maintaining device simplicity while improving reliability.
Data Source
AI summary
A semiconductor device according to an embodiment includes a semiconductor substrate, source electrodes, drain electrodes provided between the source electrodes, gate electrodes provided between the source electrodes and the drain electrodes, first p-type region in the semiconductor substrate, n-type source regions in the semiconductor substrate extending in a first direction and electrically connected to the source electrodes, n-type drain regions in the semiconductor substrate extending in the first direction and electrically connected to the drain electrodes, and first n-type regions extending in the first direction, the first p-type region interposed between the first n-type regions and the n-type source regions, the first p-type region interposed between the first n-type regions and the n-type drain regions. A distance between one first n-type region among the first n-type regions and the source electrodes is less than a distance between the one first n-type region and the drain electrodes.