Bipolar Transistor Fabrication Using Composite Base Region
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Solution Overview
Problem
The existing fabrication processes for integrated circuits, particularly those involving power MOSFET devices, are not conducive to efficiently producing bipolar transistors, as they require customized procedures that leave limited resources for other semiconductor devices, making it costly to implement processes for fabricating bipolar transistors.
Innovation Solution
The development of semiconductor devices with a buried conduction path, which includes a composite base region with a base link region electrically connecting a base contact region to a buried region, allowing for a buried conduction path between emitter and collector regions, decouples current gain and Early voltage, and is fabricated using existing implantation procedures for FET devices, avoiding additional process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If customized fabrication procedures are implemented for bipolar transistors, then bipolar transistor performance is improved, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent applies universality by designing a bipolar transistor fabrication process that uses the same implantation procedures and process steps as power MOSFET fabrication. The composite base region structure and shared process flow allow a single fabrication line to produce both device types without reconfiguration, making the manufacturing system multi-functional and eliminating the need for dedicated bipolar fabrication lines.
Solution Approach 2:
The patent merges the fabrication processes for bipolar transistors and power MOSFETs into a unified process flow. Both device types share common implantation steps, annealing processes, and thermal cycles. The composite base region fabrication is integrated into the existing MOSFET process sequence, combining what were previously separate manufacturing operations into a single coordinated process.
2Manufacturing precision
If customized implantation procedures are used for bipolar transistors, then device performance is improved, but manufacturing cost increases
Solution Approach 1:
The implantation procedures are designed to be universal, serving both bipolar transistor and power MOSFET fabrication. The same ion implantation equipment, doping profiles, and thermal processing parameters are used for both device types, eliminating the need for separate specialized equipment or procedures and reducing manufacturing costs through process standardization.
Solution Approach 2:
The fabrication process is self-service in that the existing power MOSFET manufacturing infrastructure automatically supports bipolar transistor production without requiring additional specialized equipment or procedures. The shared process flow leverages the already-optimized MOSFET fabrication capabilities to produce bipolar devices, making the system self-sufficient.
3Manufacturing precision
If separate fabrication processes are maintained for different device types, then device-specific optimization is achieved, but resource allocation becomes inefficient
Solution Approach 1:
The fabrication process achieves universality by creating a single process flow that can produce both bipolar transistors and power MOSFETs with equal effectiveness. The process is adaptable to different device types through selective application of implantation steps and parameter adjustment, maintaining device-specific optimization while eliminating the need for separate fabrication lines.
Solution Approach 2:
The fabrication process is dynamic and adaptable, allowing the same base process flow to be configured for different device types by selectively applying specific implantation steps and adjusting processing parameters. The process can dynamically switch between producing bipolar transistors and power MOSFETs based on production requirements, providing flexibility without sacrificing device-specific performance.
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 cost-effective fabrication of bipolar transistors with improved current gain, Early voltage, and breakdown voltage levels, suitable for analog, power, and system-on-a-chip technologies, without compromising existing FET device optimization.
Implementation Method 1
performing a first plurality of implantation procedures to implant dopant of a first conductivity type to form emitter and collector regions
Implementation Method 2
performing a second plurality of implantation procedures to implant dopant of a second conductivity type in the semiconductor substrate to form a composite base region
Data Source
AI summary
A method of fabricating a bipolar transistor device includes performing a first plurality of implantation procedures to implant dopant of a first conductivity type to form emitter and collector regions laterally spaced from one another in a semiconductor substrate, and performing a second plurality of implantation procedures to implant dopant of a second conductivity type in the semiconductor substrate to form a composite base region. The composite base region includes a base contact region, a buried region through which a buried conduction path between the emitter and collector regions is formed during operation, and a base link region electrically connecting the base contact region and the buried region. The base link region has a dopant concentration level higher than the buried region and is disposed laterally between the emitter and collector regions.