SOI Heterojunction Bipolar Transistor Structure With Self-Aligned Regions
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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, which increases the complexity and cost of fabrication.
Innovation Solution
A heterojunction bipolar transistor structure is developed with self-aligned emitter, base, and collector regions using semiconductor-on-insulator technologies, reducing the number of epitaxial growth passes and mask counts, where the base is within a buried insulator layer, and the emitter and collector are formed in vertical alignment with the subcollector, utilizing epitaxial growth processes and selective etching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple epitaxial growth processes and masking processes are used to manufacture heterojunction bipolar transistors, then the manufacturing precision and device performance are improved, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines multiple epitaxial growth processes and masking operations into a single integrated epitaxial growth step. The method forms the collector, base, and emitter regions simultaneously in one growth process, eliminating the need for separate masking and growth steps for each region, thereby reducing processing complexity while maintaining device performance
Solution Approach 2:
The patent uses preliminary ion implantation to create pre-doped semiconductor layers before the final epitaxial growth. This preliminary action establishes the doping profiles and region boundaries in advance, allowing the subsequent single growth step to form all device regions without requiring multiple masking operations during growth
2Manufacturing precision
If multiple repetitive epitaxial growth processes are used, then the manufacturing precision is improved, but the productivity decreases due to repetitive processing
Solution Approach 1:
The patent merges multiple repetitive epitaxial growth processes into a single growth step that forms all device regions (collector, base, emitter) simultaneously. This eliminates the repetition of growth cycles and associated masking steps, directly improving fabrication efficiency while maintaining the precision needed for device performance
3Manufacturing precision
If multiple masking processes are used, then the manufacturing precision is improved, but the ease of manufacture deteriorates due to increased process complexity
Solution Approach 1:
The patent performs preliminary ion implantation to define region boundaries and doping profiles before the final epitaxial growth. This preliminary action establishes precise region locations in advance, allowing the subsequent single growth step to form all regions without requiring multiple masking operations, thereby simplifying manufacturing while maintaining alignment precision
Solution Approach 2:
The patent combines multiple masking operations into a single growth process where all device regions are formed simultaneously. The preliminary ion implantation patterns serve as the only masking step, eliminating subsequent masking requirements and greatly simplifying the manufacturing process
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 the manufacturing costs and reduces parasitic components, achieving a more efficient and cost-effective method for producing heterojunction bipolar transistors with improved performance.
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
Figure 1A
Figure 1B
Figure 1C
AI summary
A structure comprising: 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.