Buried Contacts in Bipolar Transistors for Area Reduction
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Solution Overview
Problem
Semiconductor devices, such as vertical PNP bipolar transistors, face challenges in miniaturization and component densification due to large design requirements and increased collector-substrate capacitance, which are costly and time-consuming to address with existing solutions.
Innovation Solution
The implementation of buried contacts within the collector of bipolar transistors to a sufficient depth for adequate contact, eliminating the need for large collector tubs and reducing device size without significant production costs or increased capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large PTUB and base contact separation is used to achieve optimum emitter base breakdown voltage, then breakdown voltage performance is improved, but device area increases excessively
Solution Approach 1:
The patent transitions from a planar contact structure to a three-dimensional buried contact structure that extends vertically into the collector region. By forming the contact in a trench that penetrates through the collector to reach the PTUB, the design achieves adequate electrical contact without requiring large lateral separation distances, thus resolving the contradiction between breakdown voltage performance and device area.
2Object-affected harmful factors
If deep trench isolation process is used to reduce collector-substrate capacitance, then capacitance is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The buried contact structure serves multiple functions: it provides electrical contact to the PTUB, acts as an isolation structure between the collector and substrate, and reduces collector-substrate capacitance. By combining these functions into a single structure, the patent eliminates the need for separate deep trench isolation processes, thereby reducing manufacturing complexity while achieving the desired capacitance reduction.
Solution Approach 2:
The patent merges the contact formation function with the isolation function into a single buried contact structure. The trench that forms the buried contact also serves as the isolation structure, combining what were previously separate processing steps into one integrated structure, thus reducing overall process complexity.
3Reliability
If n-isolation regions are used under the collector to isolate from p-substrate, then isolation is achieved, but collector-substrate capacitance increases
Solution Approach 1:
The patent extracts the isolation function from the traditional n-isolation region approach and integrates it directly into the buried contact structure. By forming the buried contact trench that extends through the collector and into the substrate, the isolation is achieved at the contact interface itself, eliminating the need for separate n-isolation regions that would increase capacitance.
Data Source
AI summary
The invention, in one aspect, provides a semiconductor device that includes a collector for a bipolar transistor located within a semiconductor substrate and a buried contact, at least a portion of which is located in the collector to a depth sufficient that adequately contacts the collector.