Gate-Aligned Lateral Bipolar Transistor for High-Speed RF Control
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Solution Overview
Problem
Vertical bipolar transistors face limitations in high-speed operation due to increased collector resistance and complex manufacturing processes, while lateral bipolar transistors offer a simpler structure but require innovative designs for enhanced performance.
Innovation Solution
The design incorporates an extrinsic base region with a gate structure comprising a gate dielectric material and gate control, aligned with the extrinsic base region, allowing for direct collector electrode contact and improved controllability, suitable for high-speed applications like millimeter waveband devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vertical bipolar transistor structure is used, then the transistor can be manufactured with established processes, but the collector resistance increases and high-speed operation is limited
Solution Approach 1:
The patent inverts the conventional vertical bipolar transistor architecture by adopting a lateral configuration where the current flow path is reversed relative to the substrate thickness direction. This inversion places the collector region closer to the substrate surface and the emitter region deeper, fundamentally changing the carrier transport path to reduce collection resistance and enable high-speed operation.
Solution Approach 2:
The patent transitions from a vertical current flow configuration to a lateral current flow configuration, changing the dimensionality of carrier transport. This dimensional change allows the collector electrode to directly contact the collector region without traversing the full substrate thickness, reducing resistance and improving speed performance.
2Reliability
If a vertical bipolar transistor structure is used, then the transistor can be manufactured with standard processes, but the number of process steps increases and costs increase
Solution Approach 1:
The lateral bipolar transistor structure can be integrated with existing CMOS fabrication processes, allowing the same manufacturing platform to produce both bipolar and CMOS devices. This multi-functionality reduces the need for separate specialized process lines and decreases overall manufacturing complexity and cost.
3Speed
If a lateral bipolar transistor structure is used, then the structure is simpler and collector electrode can directly contact collector region, but the transistor lacks advanced control mechanisms
Solution Approach 1:
The patent merges the gate structure with the extrinsic base region, integrating the control mechanism directly into the base. This combination allows the gate to effectively modulate the base current and provide advanced control over the transistor operation, while maintaining the simple lateral structure that enables high-speed performance.
Solution Approach 2:
The gate structure acts as an intermediary control element that modulates the electrical characteristics of the extrinsic base region. By positioning the gate within or adjacent to the base region, it provides precise control over carrier injection and transport, enabling advanced controllability without complicating the overall lateral transistor architecture.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a lateral bipolar transistor and methods of manufacture. The structure includes: an extrinsic base region; an emitter region on a first side of the extrinsic base region; a collector region on a second side of the extrinsic base region; and a gate structure comprising a gate oxide and a gate control in a same channel region as the extrinsic base region.