Hybrid Substrate FinFET Crystal Orientation
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Solution Overview
Problem
Conventional hybrid substrate schemes for FinFET devices with fins of different sidewall crystalline orientations have not been entirely satisfactory in enhancing electron and hole mobility, leading to performance issues and fin height loss.
Innovation Solution
A hybrid substrate scheme is implemented where PMOS FinFET devices have a fin with a (100) crystal orientation top surface and a (110) crystal orientation sidewall, and NMOS FinFET devices have a fin with a (110) crystal orientation top surface and a (100) crystal orientation sidewall, with capping layers to improve interface state density and gate dielectric/semiconductor interface, ensuring equal fin heights for both devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hybrid substrate schemes are used with fins of different sidewall crystalline orientations, then device performance should be improved, but fin height loss occurs and interface state density increases
Solution Approach 1:
The patent applies local quality by providing different crystal orientations at different locations on the substrate surface. Specifically, a first region has a first crystal orientation (e.g., <100>) optimized for NMOS devices, while a second region has a second crystal orientation (e.g., <110>) optimized for PMOS devices. This allows each device type to have optimal local properties without compromising the other, thereby improving overall device performance while maintaining precise fin height control through the unified substrate structure.
2Reliability
If different sidewall crystalline orientations are used for PMOS and NMOS fins, then electron and hole mobility should be enhanced, but capacitor loss increases
Solution Approach 1:
The patent implements local quality by assigning specific crystal orientations to different device regions: <100> orientation for NMOS regions to enhance electron mobility, and <110> orientation for PMOS regions to enhance hole mobility. This localized optimization improves carrier mobility for each device type while the unified substrate and consistent fin formation process minimize capacitor loss by avoiding the fin height variations that occur in conventional separate substrate approaches.
3Reliability
If hybrid substrate with different crystal orientations is implemented, then interface state density should be improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single unified substrate structure. The substrate simultaneously provides different crystal orientations for NMOS and PMOS devices, maintains uniform fin height across both device types, and ensures proper interface state density. This consolidation achieves the benefits of hybrid substrate schemes while reducing device complexity by eliminating the need for separate substrates or complex fin height adjustment mechanisms.
Data Source
AI summary
A semiconductor device includes PMOS and NMOS FinFET devices disposed on a hybrid substrate including a first substrate and a second substrate, in which a fin of the PMOS FinFET device is formed on the first substrate having a top surface with a (100) crystal orientation, and another fin of the NMOS FinFET device is formed on the second substrate having a top surface with a (110) crystal orientation. The semiconductor device further includes a capping layer enclosing a buried bottom portion of the fin of the PMOS FinFET device, and another capping layer enclosing an effective channel portion of the fin of the PMOS FinFET device.