SOI Heterojunction Bipolar Transistor Layout With Lower Parasitic Capacitance
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Solution Overview
Problem
The manufacturing of heterojunction bipolar transistors is complex and costly due to multiple repetitive epitaxial growth processes and masking steps, leading to high costs and parasitic components in conventional structures.
Innovation Solution
A heterojunction bipolar transistor structure with self-aligned emitter, base, and collector regions using semiconductor-on-insulator technology, where the base is within a buried insulator layer, reducing the number of epitaxial growth passes and mask counts, and employing epitaxial growth processes to form the collector, base, and emitter in a single or fewer processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple epitaxial growth processes and masking processes are used to manufacture heterojunction bipolar transistors, then the device structure can be formed, but the manufacturing cost increases and the process complexity increases
Solution Approach 1:
The patent combines multiple epitaxial growth processes into a single integrated process. The heterojunction bipolar transistor structure is formed by growing the collector, base, and emitter regions in one continuous epitaxial growth step, eliminating the need for separate growth processes and multiple masking steps. This merging of processes directly reduces manufacturing cost and process complexity while maintaining the required device structure.
2Object-affected harmful factors
If conventional heterojunction bipolar transistor structures are used, then the device can be manufactured, but parasitic capacitance increases
Solution Approach 1:
The patent positions the base region within the buried insulator layer, utilizing the vertical dimension and the insulator layer space that would otherwise be unused. This dimensional arrangement allows the base to be embedded in the insulator, creating physical separation that reduces parasitic capacitance between the base and collector while maintaining proper device functionality.
3Manufacturing precision
If multiple masking processes are used, then precise alignment can be achieved, but the number of process steps increases
Solution Approach 1:
The patent eliminates multiple masking processes by integrating the formation of collector, base, and emitter regions into a single epitaxial growth process. The precise alignment is achieved through in-situ growth control rather than sequential masking steps, thereby reducing the total number of process steps while maintaining manufacturing precision.
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 lowers manufacturing costs and reduces parasitic components, achieving lower parasitic capacitance and cost-effectiveness while maintaining performance in micrometer and nanometer scale dimensions.
Implementation Method 1
forming a collector above the subcollector and a base within the buried insulator layer in a single epitaxial growth process; forming an emitter above the base in another epitaxial growth process
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to heterojunction bipolar transistors and methods of manufacture. The structure includes: a subcollector under a buried insulator layer; a collector above the subcollector; a base within the buried insulator layer; an emitter above the base; and contacts to the subcollector, the base and the emitter.