Fin Transistor Channel Sub-Channel Regions Mitigate Contamination
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Solution Overview
Problem
In the fabrication of fin-containing transistors, particularly germanium (Ge) containing silicon (Si) transistors, chemical contamination and segregation at the channel-gate oxide interface adversely affect electron and hole mobility due to the enhanced reactivity of SiGe with foreign elements during processing, and existing protective layers are not scalable with decreasing gate lengths and are costly.
Innovation Solution
The method involves forming semiconductor integrated circuits with distinct channel and sub-channel regions, where the sub-channel region has a wider width than the channel region, and the surface chemical composition of the sub-channel region includes elements like oxygen, nitrogen, carbon, chlorine, fluorine, and sulfur, which are distinct from the channel region, allowing for process-induced changes to be removed, thereby mitigating chemical contamination without the need for a protective layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a protective layer is used to prevent chemical contamination at the channel-gate interface, then chemical contamination is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the protective layer from the fin surface before gate dielectric deposition, allowing the gate dielectric to directly contact the fin surface. This eliminates the protective layer while maintaining low chemical contamination through process optimization
Solution Approach 2:
The patent changes the processing parameters to reduce chemical contamination without requiring a protective layer, achieving clean interfaces through controlled deposition and etching processes
2Object-affected harmful factors
If existing protective layers are used, then chemical contamination is mitigated, but scalability with decreasing gate lengths is lost and manufacturing cost increases
Solution Approach 1:
The protective layer is completely removed from the process flow, eliminating the scalability and cost issues associated with maintaining protective layers across different gate length technologies
Solution Approach 2:
The fin surface is prepared through process-induced changes that create a naturally clean surface suitable for direct gate dielectric deposition, eliminating the need for external protective layers
3Ease of manufacture
If the channel region is exposed to processing, then chemical contamination occurs, but process-induced changes can be removed through etching and cleaning
Solution Approach 1:
Etching and cleaning processes are performed on the fin surface before gate dielectric deposition to remove process-induced changes and chemical contamination, preparing a clean surface for subsequent processing
Solution Approach 2:
The patent converts the harmful effect of chemical contamination into a benefit by using controlled etching and cleaning processes that remove contaminants while preparing the surface for optimal gate dielectric adhesion
Data Source
AI summary
Integrated circuits include fins including an upper/channel region and a lower/sub-channel region, the lower region having a first chemical composition and opposing sidewalls adjacent to an insulator material, and the upper region having a second chemical composition. A first width indicates the distance between the opposing sidewalls of the lower region at a first location is at least 1 nm wider than a second width indicating the distance between the opposing sidewalls of the upper region at a second location, the first location being within 10 nm of the second location (or otherwise relatively close to one another). The first chemical composition is distinct from the second chemical composition and includes a surface chemical composition at an outer surface of the opposing sidewalls of the lower region and a bulk chemical composition therebetween, the surface chemical composition including one or more of oxygen, nitrogen, carbon, chlorine, fluorine, and sulfur.