Heterojunction Bipolar Transistor Sensor with Front-End Cavities
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Solution Overview
Problem
Transistor-based sensors face challenges in cost and complexity due to the need for large sense areas in back-end-of-line structures and non-standard packaging for solution reception, which increases fabrication costs and reduces efficiency.
Innovation Solution
A semiconductor structure with alternating polycrystalline and single-crystal sections, featuring cavities formed through etching, allows for fluid inlet and outlet openings, reducing the footprint and packaging complexity by relocating the solution-receiving cavities to the front-end-of-line processing, enabling efficient sensor fabrication and integration with other circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large sense area is reserved in the back-end-of-line structure for cavity formation, then the sensor can receive solutions effectively, but the chip footprint increases and fabrication costs increase
Solution Approach 1:
The patent relocates the solution-receiving cavities from the back-end-of-line structure to the front-end-of-line structure, utilizing the vertical dimension and alternative spatial arrangement. This dimensional repositioning allows solution reception without requiring large areas in the traditional back-end location, thereby reducing chip footprint while maintaining sensing functionality.
Solution Approach 2:
The cavities are formed during front-end-of-line processing rather than back-end-of-line processing. This preliminary action integrates cavity formation into earlier fabrication steps, eliminating the need to reserve large sense areas later in the process and reducing overall chip area requirements.
2Ease of operation
If non-standard packaging is used for solution reception, then the sensor can function properly, but packaging complexity and fabrication costs increase
Solution Approach 1:
The patent merges the cavity formation process with the front-end-of-line fabrication process, combining what were previously separate operations (standard fabrication and non-standard packaging for solution reception) into a single integrated process. This eliminates the need for non-standard packaging while maintaining solution reception capability.
Solution Approach 2:
The front-end-of-line structure is designed to serve multiple functions: it maintains standard fabrication compatibility while simultaneously providing solution-receiving cavities. This multi-functionality eliminates the need for specialized non-standard packaging, reducing packaging complexity.
3Ease of operation
If cavities are formed in the back-end-of-line structure, then solution reception is enabled, but fabrication costs increase
Solution Approach 1:
The cavities are formed during front-end-of-line processing rather than back-end-of-line processing. This preliminary action integrates cavity formation into earlier, more cost-effective fabrication steps, reducing overall manufacturing costs while enabling solution reception.
Solution Approach 2:
The patent merges cavity formation with standard front-end fabrication processes, combining what were previously separate operations into one integrated process. This eliminates the need for additional costly back-end modifications while maintaining solution reception functionality.
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
This approach reduces the impact on the chip footprint, lowers fabrication costs, and simplifies packaging, while enabling the integration of sensors with other components like heterojunction bipolar transistors for various sensing applications.
Implementation Method 1
partially removing the first plurality of sections with an etching process to define a plurality of cavities in the semiconductor layer
Data Source
AI summary
Transistor-based sensors and fabrication methods for a transistor-based sensor. A semiconductor layer is arranged over a substrate, and an interconnect structure is arranged over the semiconductor layer and the substrate. The semiconductor layer includes first sections composed of a semiconductor material, second sections composed of the semiconductor material, and cavities. The first sections have an alternating arrangement with the second sections in a lateral direction. The semiconductor material of the first sections is polycrystalline, and the semiconductor material of the second sections is single-crystal. First and second openings each extend in a vertical direction through the metallization levels of the interconnect structure to the semiconductor layer or through the substrate to the semiconductor layer. The first opening defines a first fluid inlet coupled to the cavities, and the second opening defines a first fluid outlet coupled to the cavities.