GAA Transistor Channel Orientation for Mobility
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Solution Overview
Problem
The scaling down of semiconductor integrated circuits leads to increased complexity and reduced carrier mobility due to atomic steps on silicon substrates, which affects the performance of multi-gate devices like GAA transistors.
Innovation Solution
A method is developed to fabricate semiconductor devices by aligning the active regions perpendicular to the atomic step propagation direction, utilizing the terrace direction for improved carrier mobility, which involves determining the atomic step structure and adjusting the channel member thickness to minimize scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multi-gate structures are used with standard fabrication processes, then device density and gate control are improved, but carrier mobility deteriorates due to scattering at atomic steps
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the channel member orientation relative to the atomic step propagation direction. Instead of aligning channels perpendicular to steps (conventional symmetric approach), the channels are oriented at a specific angle (e.g., 45 degrees) to exploit the terrace directions between steps, thereby reducing scattering while maintaining gate control benefits of multi-gate structures
Solution Approach 2:
The patent changes the geometric parameter of channel member thickness to below 10 nm and adjusts the orientation angle relative to atomic steps. By modifying these parameters, the device achieves improved carrier mobility through reduced scattering at atomic steps while maintaining effective gate control, thus resolving the contradiction between manufacturing precision and reliability
2Productivity
If channel member thickness is reduced to increase device density, then production efficiency is improved, but carrier mobility deteriorates due to increased scattering at atomic steps
Solution Approach 1:
The patent introduces a new dimensional consideration by incorporating the angular orientation of channel members relative to atomic step propagation directions. This additional dimensional parameter (orientation angle) allows the system to achieve high device density through thin channels while simultaneously maintaining high carrier mobility by orienting channels along terrace directions that minimize scattering, thus resolving the contradiction between productivity and reliability
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 enhances carrier mobility and device performance by reducing scattering, particularly when the channel member thickness is below 10 nm, leading to increased field effect mobilities and improved device performance.
Implementation Method 1
Due to reduced dimensions of the channel members, such atomic steps may cause scattering of charge carriers and reduce carrier mobility in the channel members
Data Source
AI summary
A semiconductor device according to the present disclosure includes a substrate including a plurality of atomic steps that propagate along a first direction, and a transistor disposed on the substrate. The transistor includes a channel member extending a second direction perpendicular to the first direction, and a gate structure wrapping around the channel member.