Segmented-Gate Fin BJT Layout for Leakage and ΔVbe Stability
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Solution Overview
Problem
As semiconductor technology advances into nanometer process nodes, bipolar junction transistors (BJTs) face challenges in maintaining performance and reducing leakage due to the shrinking feature sizes, which affects the stability of the base-emitter voltage (ΔVbe) and overall device reliability.
Innovation Solution
The formation of BJTs using FinFET processes, where p-type and n-type FinFET transistors are tied together to form collector, base, and emitter terminals, with separate gate structures over the emitter and base terminals to reduce leakage and improve ΔVbe stability, and the surface area of BJTs is expanded to provide appropriate spacing between gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but leakage increases and device reliability deteriorates
Solution Approach 1:
The gate structure is segmented into multiple portions (first gate portion, second gate portion, third gate portion) that are physically separated and independently controlled. This segmentation allows each gate portion to be optimized for specific functions, reducing leakage between adjacent regions while maintaining high integration density through efficient space utilization.
Solution Approach 2:
Different regions of the device are assigned different doping types (p-type and n-type FinFET transistors) and different gate control strategies. The emitter terminal region uses one doping type while the collector terminal uses another, allowing localized optimization of electrical properties to reduce leakage and improve reliability in each specific region.
2Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but base-emitter voltage stability deteriorates
Solution Approach 1:
The gate structure is divided into separate portions with independent control, allowing precise regulation of the base-emitter voltage. The first gate portion controls the emitter region while the second and third gate portions control the collector region, enabling independent optimization of voltage stability without compromising integration density.
Solution Approach 2:
The segmented gate structure acts as an intermediary control mechanism between the emitter and collector terminals. By introducing separate gate portions that can be independently biased, the device achieves better voltage stability through intermediate control stages that buffer and regulate voltage variations.
3Reliability
If separate gate structures are implemented over emitter and base terminals, then leakage is reduced and voltage stability improves, but device complexity increases
Solution Approach 1:
Multiple gate portions are merged into a unified gate structure that spans across different terminals. The first, second, and third gate portions are combined in a single continuous structure that provides both separation for leakage reduction and integration for simplified fabrication, balancing complexity reduction with performance improvement.
Solution Approach 2:
The gate structure serves multiple functions simultaneously: it controls current flow, reduces leakage, stabilizes voltage, and provides structural support. By designing a single gate structure that performs all these functions, the device avoids the complexity of multiple separate components while achieving the desired reliability improvements.
Data Source
AI summary
Embodiments include a first set of fins having an emitter of a bipolar junction transistor (BJT) disposed over the first set of fins, a second set of fins having a base of the BJT disposed over the second set of fins, and a third set of fins having a collector of the BJT disposed over the third set of fins. A first gate structure is disposed over the first set of fins adjacent to the emitter. A second gate structure is disposed over the second set of fins adjacent to the base. A third gate structure is disposed over the third set of fins adjacent to the collector. The first gate structure, second gate structure, and third gate structure are physically and electrically separated.