Lateral Fin BJT Structure for Easier FinFET Integration
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Solution Overview
Problem
Integration of vertical bipolar junction transistors (BJTs) with CMOS processing and fin-type field effect transistor (finFET) processing is complex and costly due to their vertical structure.
Innovation Solution
A semiconductor structure with a lateral bipolar junction transistor (BJT) is developed, featuring a base positioned laterally between a collector and an emitter, with a semiconductor fin having three portions, where the collector and emitter are on the isolation layer adjacent to the fin's sidewalls, and a dielectric layer covers the collector and emitter, allowing for easier integration with finFET processing. In heterojunction embodiments, the second portion of the fin is made of a different semiconductor material for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vertical bipolar junction transistors are used, then device performance is achieved, but integration complexity with CMOS and finFET processing increases
Solution Approach 1:
The patent transitions from a vertical BJT configuration to a lateral BJT configuration, changing the spatial arrangement from vertical stacking to horizontal positioning. This dimensional change allows the BJT to be integrated with finFET and CMOS processes without requiring complex vertical alignment and integration steps, thereby reducing integration complexity while maintaining device performance.
Solution Approach 2:
The patent inverts the conventional vertical arrangement of BJT components by positioning the base, collector, and emitter in a lateral configuration where the base is positioned between the collector and emitter horizontally rather than vertically. This inversion simplifies the integration process with standard planar CMOS and finFET manufacturing techniques.
2Reliability
If vertical bipolar junction transistors are used, then device functionality is achieved, but manufacturing cost increases
Solution Approach 1:
By changing from vertical to lateral configuration, the patent enables the use of standard planar processing techniques already established in CMOS and finFET manufacturing, avoiding the need for specialized and costly vertical integration equipment and processes.
Solution Approach 2:
The lateral BJT structure can be manufactured using the same finFET processing lines and CMOS fabrication techniques, making the manufacturing equipment and processes universal. This multi-functionality allows a single fabrication facility to produce both finFETs and lateral BJTs without requiring separate specialized production lines.
3Speed
If heterojunction bipolar transistor is used, then frequency handling performance is improved, but structural complexity increases
Solution Approach 1:
The patent applies heterojunction material composition selectively in specific regions of the lateral BJT structure, particularly in the base and collector regions, to enhance frequency handling performance. This localized use of different semiconductor materials (e.g., SiGe) provides performance improvement without requiring the entire structure to be complex, maintaining simplicity in other areas.
Solution Approach 2:
The patent employs composite semiconductor materials, combining different materials such as silicon and silicon germanium in specific layers and regions of the lateral HBT structure. This use of composite materials enables improved frequency handling performance through optimized carrier transport and junction characteristics while maintaining a relatively simple lateral structural configuration.
Data Source
AI summary
In a disclosed semiconductor structure, a lateral bipolar junction transistor (BJT) has a base positioned laterally between a collector and an emitter. The base includes a semiconductor fin with a first portion that extends from a substrate through an isolation layer, a second portion on the first portion, and a third portion on the second portion. The collector and emitter are on the isolation layer and positioned laterally immediately adjacent to opposing sidewalls of the second portion of the semiconductor fin. In some embodiments, the BJT is a standard BJT where the semiconductor fin (i.e., the base), the collector, and the emitter are made of the same semiconductor material. In other embodiments, the BJT is a heterojunction bipolar transistor (HBT) where a section of the semiconductor fin (i.e., the base) is made of a different semiconductor material for improved performance. Also disclosed is a method of forming the structure.