Segmented Mesa Transistor Structure to Prevent Turn-Off Latch-Up
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Solution Overview
Problem
Transistor devices are prone to parasitic bipolar transistor activation due to self-biasing substrate current, leading to undesirable latch-up conditions during turn-off, which existing technologies fail to effectively prevent while maintaining desirable on-resistance.
Innovation Solution
The transistor structure incorporates alternating source region segments and body region segments of opposite conductivity types within the mesa region, reducing base resistance without affecting the channel area, thereby preventing parasitic bipolar device turn-on and minimizing latch-up conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transistor structure is used, then the device can operate, but parasitic bipolar transistor activation occurs due to self-biasing substrate current, leading to latch-up conditions during turn-off
Solution Approach 1:
The transistor structure segments the source and body regions into alternating segments along the channel, creating a segmented pattern that disrupts the continuous path for parasitic bipolar transistor activation. This segmentation prevents the self-biasing substrate current from triggering latch-up conditions while maintaining device operation.
Solution Approach 2:
The patent applies different conductivity types locally within the mesa region by creating alternating source region segments (first conductivity type) and body region segments (second conductivity type). This local differentiation of electrical properties prevents parasitic bipolar transistor activation in specific locations while maintaining overall device functionality.
2Reliability
If the base resistance is reduced to prevent parasitic bipolar turn-on, then latch-up conditions are minimized, but the on-resistance may be affected
Solution Approach 1:
The alternating segmented structure allows for reduced base resistance through optimized segment geometry and spacing, while the segmented configuration maintains appropriate on-resistance by preserving the channel area. The segmentation enables independent optimization of base resistance and on-resistance parameters.
Solution Approach 2:
The patent optimizes parameters such as segment width, segment spacing, and doping concentrations to achieve the desired balance between base resistance reduction and on-resistance maintenance. By adjusting these parameters, the structure minimizes latch-up conditions while preserving energy efficiency.
3Area of stationary object
If the mesa width is minimized to reduce area, then device area is reduced, but manufacturing precision and performance may be compromised
Solution Approach 1:
The segmented structure allows for minimized mesa width while maintaining manufacturing precision through the periodic pattern. The alternating source and body region segments create a self-defining pattern that is easier to manufacture with precise control, as the segments provide natural reference points for alignment and dimension control.
Data Source
AI summary
In one general aspect, an apparatus can include a first trench disposed in a semiconductor region and including a gate electrode and a second trench disposed in the semiconductor region. The apparatus can include a mesa region disposed between the first trench and the second trench. The apparatus can include a source region segment of a first conductivity type disposed in a first side of the mesa region where the source region segment is included in a plurality of source region segments and where the plurality of source region segments are aligned along the longitudinal axis. The apparatus can include a body region segment of a second conductivity type disposed in a second side of the mesa region opposite the first side of the mesa region and having a portion disposed above the source region segment where the body region segment is included in a plurality of body region segments.