Si/SiGe Superlattice BJTs for Shared GAAFET Integration
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Solution Overview
Problem
The semiconductor industry faces challenges in scaling down semiconductor devices like bipolar junction transistors while maintaining compatibility with emerging 3-D FET technologies, such as GAAFETs, due to increased manufacturing complexity and the need for a shared substrate process.
Innovation Solution
The formation of P-N-P and N-P-N bipolar junction transistors on a silicon/silicon germanium stack using ion implantation to create emitter, base, and collector regions within a superlattice structure, which is compatible with GAAFET processes, allowing for simultaneous fabrication of 3-D FETs and bipolar junction transistors on a shared substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor devices are scaled down to increase storage capacity and processing speed, then device performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies a shared substrate process that enables simultaneous fabrication of both GAAFETs and BJTs on the same semiconductor substrate. This multi-functional approach allows the manufacturing process to produce multiple device types without requiring separate dedicated substrates, thereby improving productivity while managing manufacturing complexity through process integration
Solution Approach 2:
The patent merges the fabrication processes for GAAFETs and BJTs into a unified manufacturing flow. By combining the formation of emitter, base, and collector regions with the GAAFET structure formation into a single integrated process, the patent achieves scaled device performance while avoiding the multiplication of separate manufacturing lines that would increase complexity
2Adaptability or versatility
If bipolar junction transistors are fabricated on a shared substrate with GAAFETs, then integration capabilities are enhanced, but manufacturing process compatibility challenges arise
Solution Approach 1:
The patent employs selective doping techniques where specific regions of the substrate receive different dopant treatments tailored to the requirements of either GAAFETs or BJTs. This local quality approach allows the same substrate to support different device structures with their specific electrical requirements, enhancing integration while maintaining manufacturability through region-specific process optimization
Solution Approach 2:
The manufacturing process is segmented into distinct stages where certain process steps are specifically targeted at forming GAAFET structures while other steps are optimized for BJT region formation. This segmentation allows each device type to receive the appropriate manufacturing treatment at the right time, resolving compatibility challenges while achieving high integration
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 enables the efficient fabrication of compact and high-performance bipolar junction transistors that can coexist with GAAFETs on the same substrate, enhancing device performance and integration capabilities, particularly suitable for applications in high-power and RF signal amplifiers.
Implementation Method 1
implanting selected regions of the superlattice structure with dopants to form emitter, base, and collector regions
Data Source
AI summary
Bipolar junction transistors (BJTs) are disclosed that are formed on a superlattice structure of stacked silicon and silicon germanium layers. The superlattice structure can be implanted with ions to form emitter, base, and collector regions of the BJTs. Altering width ratios of the implanted emitter, base, and collector regions can tune BJT performance. The BJTs can be implemented in a Darlington circuit configuration.