Lateral Bipolar Transistor Spacer Layout for Lower Parasitics
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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 are simpler but require additional steps for high-speed performance.
Innovation Solution
A lateral bipolar junction transistor structure with a bilayer dielectric spacer on the extrinsic base region, separating the extrinsic collector and emitter from the extrinsic base, and integrated with a metal oxide semiconductor field effect transistor using the same semiconductor material, enabling reduced resistance and parasitic reduction through epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a vertical bipolar transistor structure is used, then the transistor can be formed with standard processes, but collector resistance increases and high-speed performance 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 allows the collector to be positioned at the surface level rather than deep in the substrate, thereby reducing collector resistance and improving high-speed performance while maintaining compatibility with standard semiconductor manufacturing processes
2Device complexity
If a lateral bipolar transistor is used, then the structure is simpler and collector contact is direct, but additional process steps are required to achieve high-speed performance
Solution Approach 1:
The patent merges the lateral bipolar transistor structure with standard CMOS fabrication processes, integrating the formation of extrinsic base regions, dielectric spacers, and p-n junctions into existing process flows. This combination allows the lateral bipolar transistor to maintain its structural simplicity while achieving high-speed performance without requiring entirely separate or additional process steps
Solution Approach 2:
The patent employs preliminary formation of dielectric spacers on the sidewalls of extrinsic base regions before final junction creation. This preliminary action establishes precise geometric constraints and electrical isolation early in the process, enabling subsequent high-speed performance optimization without requiring complex post-processing steps
3Reliability
If emitter and collector regions are directly contacted to extrinsic base, then resistance is reduced, but parasitic capacitance increases
Solution Approach 1:
The patent introduces dielectric spacers as intermediary elements positioned between the emitter/collector regions and the extrinsic base. These spacers serve dual functions: they maintain the low-resistance electrical contact pathways while simultaneously providing electrical isolation that reduces parasitic capacitance between adjacent regions, thus resolving the contradiction between contact reliability and parasitic reduction
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 a lateral bipolar junction transistor including an extrinsic base region and a bilayer dielectric spacer on sidewalls of the extrinsic base region, and a p-n junction positioned under the bilayer dielectric spacer between the extrinsic base region and at least an emitter region.