Fin-Type Lateral BJT With Cavity Isolation for Leakage Reduction
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Solution Overview
Problem
Current BJT devices face challenges in reducing leakage current, power consumption, and thermal dissipation, particularly due to high base-bulk leakage current, which hinders the improvement of operating speed and performance in integrated circuit products like SoC chips.
Innovation Solution
A fin-type lateral bipolar junction transistor (BJT) device is designed with a cavity in the semiconductor substrate filled with insulating material, physically separating the intrinsic base region from the substrate, thereby reducing leakage current and improving thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional BJT device structure is used without cavity isolation, then the device structure is simpler and easier to manufacture, but the base-bulk leakage current is high which limits operating speed and performance
Solution Approach 1:
The device structure is segmented by introducing a cavity that physically divides the base region from the bulk substrate, creating distinct isolation zones. This segmentation reduces base-bulk leakage current by approximately ten times while maintaining manufacturability through standard semiconductor fabrication processes.
Solution Approach 2:
The isolation mechanism transitions from two-dimensional planar isolation to three-dimensional vertical cavity isolation. By etching cavities into the substrate and filling them with insulating material, the patent creates vertical separation between the base region and bulk substrate, effectively reducing leakage current without significantly increasing lateral device footprint.
2Reliability
If the base region is physically separated from the substrate using a cavity, then leakage current is reduced, but the device structure becomes more complex
Solution Approach 1:
An insulating material is introduced as an intermediary substance filling the cavity between the base region and bulk substrate. This intermediary provides effective electrical isolation and leakage current reduction while the cavity structure itself remains relatively simple to fabricate using standard etching and deposition processes.
3Speed
If leakage current is reduced through structural modifications, then operating speed improves, but manufacturing complexity increases
Solution Approach 1:
The cavity structure is formed preliminarily during the substrate preparation phase, before device fabrication begins. By pre-establishing the isolation cavities and filling them with insulating material, the patent enables subsequent device formation to proceed with standard processes, achieving high operating speed without compounding manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly decreases base-to-bulk substrate leakage current by approximately ten times and enhances thermal dissipation, allowing the BJT device to operate at speeds comparable to those on SOI substrates while providing electrical isolation between devices.
Implementation Method 1
a cavity formed in a semiconductor substrate and filled with an insulating material, the cavity physically separating a lower surface of the intrinsic base region from the semiconductor substrate
Implementation Method 2
filled with an insulating material, the cavity physically separating a lower surface of the intrinsic base region from the semiconductor substrate
Data Source
AI summary
A lateral bipolar junction transistor (BJT) device includes: an emitter region, a collector region, and a base region, the base region positioned between and laterally separating the emitter region and the collector region, the base region including an intrinsic base region; and a cavity formed in a semiconductor substrate and filled with an insulating material, the cavity physically separating a lower surface of the intrinsic base region from the semiconductor substrate.