Multi-Bridge-Channel BJT Structure for Scaled Gate Control
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Solution Overview
Problem
Conventional bipolar junction transistors (BJTs) are not satisfactory in all aspects, particularly in terms of complexity and scalability, as they struggle to maintain gate control and prevent short-channel effects when scaled down for advanced semiconductor devices.
Innovation Solution
The development of BJT structures integrated with multi-bridge-channel (MBC) transistors, featuring two source/drain features over a doped well region, with a backside power rail and isolation structures to prevent shorting, allowing for improved routing and reduced footprint, enabling better gate control and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bipolar junction transistors are scaled down to improve device density, then device density is improved, but gate control deteriorates and short-channel effects increase
Solution Approach 1:
The patent transitions from planar 2D channel structures to three-dimensional multi-bridge-channel structures that extend vertically and wrap around the gate. This dimensional change enables better gate control over the channel while maintaining scaled-down footprints, directly resolving the contradiction between device density and gate control effectiveness
Solution Approach 2:
The multi-bridge-channel structure implements nested configurations where channels are arranged in hierarchical layers with wrap-around gates. The channels are positioned at different heights and angles, creating a nested architecture that maximizes gate-channel coupling while minimizing the device footprint, thereby improving both density and control
2Area of moving object
If conventional bipolar junction transistors are scaled down to reduce device footprint, then device footprint is reduced, but short-channel effects increase
Solution Approach 1:
By extending the channel structure into the third dimension with vertical bridges and wrap-around gates, the patent achieves longer effective channel lengths within smaller planar footprints. This dimensional approach allows the channel to extend further in the vertical direction while maintaining compact horizontal dimensions, thereby reducing short-channel effects without sacrificing density
Solution Approach 2:
The channel is divided into multiple discrete bridge segments arranged in series between source and drain regions. This segmentation creates multiple potential barriers that enhance carrier control and suppress short-channel effects, while the compact arrangement of segments maintains a small overall device footprint
3Reliability
If multi-bridge-channel structures are implemented to improve gate control, then gate control is improved, but device complexity increases
Solution Approach 1:
The multi-bridge-channel structure with wrap-around gates serves multiple functions simultaneously: it provides enhanced gate control, extends effective channel length, reduces short-channel effects, and maintains compact footprint. This multi-functionality justifies the increased structural complexity by delivering multiple performance benefits from a single architectural approach
Solution Approach 2:
The patent combines multiple channel bridges, wrap-around gates, and isolation structures into an integrated multi-gate device architecture. By merging these elements into a unified structure rather than separate components, the design achieves improved gate control while managing overall device complexity through functional integration
Data Source
AI summary
The present disclosure provides embodiments of bipolar junction transistor (BJT) structures. A BJT according to the present disclosure includes a first epitaxial feature disposed over a well region, a second epitaxial feature disposed over the well region, a vertical stack of channel members each extending lengthwise between the first epitaxial feature and the second epitaxial feature, a gate structure wrapping around each of the vertical stack of channel members, a first electrode coupled to the well region, an emitter electrode disposed over and coupled to the first epitaxial feature, and a second electrode disposed over and coupled to the second epitaxial feature.