Isolated Bipolar Junction Transistor Using Buried Layer Barrier
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Solution Overview
Problem
Conventional vertical bipolar junction transistors (BJTs) face challenges in isolating fully from the substrate, leading to undesired carrier injection and parasitic BJT formation, which complicates the manufacturing process and increases costs.
Innovation Solution
A bipolar junction semiconductor device is designed with a semiconductor substrate, buried layers, epitaxial layers, and isolation structures to form fully isolated PNP and NPN BJT units, creating effective barriers to prevent carrier injection and parasitic BJT formation, thereby reducing manufacturing costs and enhancing current gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep buried layer is formed to surround the vertical BJT to improve isolation performance, then the isolation performance is improved, but the manufacturing process becomes more complicated and manufacturing cost increases
Solution Approach 1:
The invention merges the isolation structure with the existing buried layer by extending the buried layer to form an isolation structure that surrounds the BJT. This combines the isolation function with the existing substrate structure, achieving full isolation without requiring separate deep buried layer formation processes, thus avoiding increased manufacturing complexity while maintaining improved isolation performance
2Reliability
If a deep buried layer is formed to surround the vertical BJT to improve isolation performance, then the isolation performance is improved, but manufacturing cost increases
Solution Approach 1:
The invention merges the isolation structure with the existing buried layer, utilizing the already-formed buried layer and extending it to provide isolation. This approach reuses existing process steps and materials, avoiding the need for additional expensive deep buried layer formation processes, thus achieving full isolation without increasing manufacturing cost
3Object-generated harmful factors
If the vertical BJT is fully isolated from the substrate, then parasitic BJT formation is prevented, but the device structure becomes more complex
Solution Approach 1:
The invention merges the isolation function with the existing buried layer structure by extending the buried layer to form an isolation structure. This integrated approach achieves full isolation that prevents parasitic BJT formation while avoiding the need for separate complex isolation structures, thus preventing harmful effects without significantly increasing device structure complexity
Data Source
AI summary
A bipolar junction semiconductor device and associated method of manufacturing, the bipolar junction semiconductor device has a P type substrate, a N type buried layer formed in the substrate, a P− type first epitaxial layer formed on the buried layer, a P− type second epitaxial layer formed on the first epitaxial layer, a PNP BJT unit formed in the first and second epitaxial layers at a first active area, a NPN BJT unit formed in the first and second epitaxial layers at a second active area and a first isolation structure of N type formed in the first and second epitaxial layers at an isolation area. The isolation area is located between the first active area and the second active area, the first isolation structure connected with the buried layer forms an isolation barrier.