Heterojunction Transistor Structure for CMOS Compatibility
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Solution Overview
Problem
Conventional transistors in CMOS fabrication processes do not provide superior performance, failing to meet current semiconductor technology needs.
Innovation Solution
A transistor structure is developed with a semiconductor substrate having regions doped with specific impurities, where the base is doped with a higher concentration of n-type impurity than the emitter region, and the collector is doped with a higher concentration of p-type impurity than the collector region, using materials like phosphorous-doped silicon carbide and boron-doped silicon germanium, and a manufacturing method that forms these regions with ion implantation and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistor structure is used in CMOS fabrication process, then manufacturing compatibility is maintained, but transistor performance is insufficient
Solution Approach 1:
The patent applies local quality by creating a heterojunction structure where the emitter region uses a different material composition (silicon germanium with specific germanium content) compared to the base and collector regions (silicon carbide). This local material differentiation in the emitter enables superior carrier injection and transistor performance while maintaining compatibility with standard CMOS fabrication processes through selective ion implantation and thermal processing steps.
Solution Approach 2:
The patent employs composite materials by combining silicon germanium (SiGe) and silicon carbide (SiC) in a heterojunction configuration. The emitter region comprises silicon germanium with 0-50% germanium content, while the base and collector regions use silicon carbide. This composite material approach enables enhanced transistor performance through the heterojunction effect, improving carrier mobility and injection efficiency while remaining manufacturable in CMOS processes.
2Reliability
If ion implantation is performed on emitter and collector regions to form P+ regions, then doping is achieved, but superior transistor performance is not obtained
Solution Approach 1:
The patent applies parameter changes by modifying the doping concentration profile, specifically creating a higher doping concentration in the base region compared to the emitter and collector regions. The base region is doped to a concentration of 1×10^19 to 1×10^21 atoms/cm³, while the emitter and collector regions have lower doping concentrations. This parameter optimization improves transistor performance by enhancing carrier injection efficiency and reducing recombination losses.
Solution Approach 2:
The patent uses composite materials (silicon germanium emitter with silicon carbide base and collector) to achieve superior performance. The heterojunction between different semiconductor materials enables better carrier selectivity and injection efficiency compared to homojunction structures, overcoming the limitations of conventional ion implantation doping approaches.
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
The proposed transistor structure enhances performance by creating heterojunctions that improve transistor efficiency and compatibility with CMOS processes, addressing the limitations of conventional transistors.
Implementation Method 1
an ion implantation process is performed on the regions corresponding to the emitter and the collector, so as to form a P+ region
Implementation Method 2
The transistor includes a semiconductor substrate comprising a first region and a second region; an emitter and a base disposed on the first region; and a collector disposed on the second region
Data Source
AI summary
A transistor includes a semiconductor substrate comprising a first region and a second region. The transistor further includes an emitter and a base disposed on the first region, and a collector disposed on the second region. The emitter includes a heterojunction. The heterojunction is at a same height as a junction between two different insulating materials that separate the emitter and the base.