Multi-Gate Transistor Work Function Layout for Threshold Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-gate transistors face challenges in achieving improved performance due to limitations in scaling and current control, particularly in managing short channel effects.
Innovation Solution
The semiconductor device incorporates a multi-gate transistor design with multiple threshold voltages, featuring a gate electrode surrounded by work function adjusting films and a high dielectric film, which includes specific configurations of metal oxide and conductive films to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-gate transistors are used to increase integration density, then device scaling is improved, but controlling multiple threshold voltages becomes more difficult
Solution Approach 1:
The patent applies local quality by implementing different work function adjusting film configurations at different locations within the gate electrode structure. Specifically, first and second work function adjusting films are deposited on different sides of the gate electrode, allowing each region to have tailored threshold voltage characteristics. This enables independent optimization of threshold voltages for different transistor types (e.g., NFET and PFET) within the same multi-gate device, thereby managing the complexity of multi-threshold voltage control while maintaining high integration density
2Reliability
If gate length is increased to improve current control, then current control capability is improved, but device scaling is reduced
Solution Approach 1:
The patent transitions from controlling current primarily through gate length (one-dimensional control) to utilizing the vertical dimension and lateral surfaces of the gate electrode. The gate electrode wraps around the active pattern, creating multi-gate contact that enables current control through the vertical channel while maintaining shorter horizontal gate lengths. This dimensional change allows improved current control capability without sacrificing device scaling
3Manufacturing precision
If work function adjusting films are added to control threshold voltages, then threshold voltage control is improved, but gate electrode complexity increases
Solution Approach 1:
The patent implements nesting by depositing work function adjusting films within the gate electrode structure itself. The first and second work function adjusting films are nested on opposite sides of the gate electrode, with each film embedded in a recess or depression formed in the gate electrode material. This nested configuration allows precise threshold voltage control through the work function adjusting films while maintaining a compact and relatively simple overall gate electrode structure
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 design improves performance by enabling better scaling and current control, effectively suppressing short channel effects and enhancing transistor functionality.
Implementation Method 1
a high dielectric film between the first active pattern and the gate electrode and between the second active pattern and the gate electrode
Implementation Method 2
the gate electrode includes a first work function adjusting film surrounding the high dielectric film on the first active pattern, a second work function adjusting film surrounding the high dielectric film on the second active pattern
Data Source
AI summary
A semiconductor device comprises a substrate, a first active pattern on the substrate and extending in a first direction, a second active pattern extending in the first direction spaced apart from the substrate, a gate electrode extending in a second direction surrounding the first and second active patterns, and a high dielectric film between the first and second active patterns and the gate electrode. The gate electrode includes first and second work function adjusting films surrounding the high dielectric film on the first and second active patterns, and a filling conductive film surrounding the first and second work function adjusting films. The first and second work function adjusting films include first and second work function conductive films, each of which includes a first metal film. A thickness of the first metal film of the first work function conductive film is greater than that of the second work function conductive film.