Carbon Gradient Work Function Film for Gate Resistance Control
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Solution Overview
Problem
The challenge in semiconductor device fabrication is to reduce gate resistance while maintaining or improving operating performance and product reliability, particularly as the scaling-down of semiconductor devices leads to increased gate resistance and difficulty in adjusting threshold voltage.
Innovation Solution
A semiconductor device is designed with a substrate, active patterns, a gate insulating film, a work function adjustment film containing carbon, and a barrier film, where the carbon concentration in the work function adjustment film increases away from the barrier film, and a carbon concentration gradient is achieved through a film treatment process to minimize surface oxide and adjust the effective work function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum feature size is scaled down to achieve higher integration, then device integration is improved, but gate resistance increases
Solution Approach 1:
The work function adjustment film is configured with a non-uniform carbon concentration distribution, where the carbon concentration increases from the interface with the barrier film toward the opposite side. This local variation in material composition allows different regions of the film to serve different functions: the region with lower carbon concentration near the barrier film maintains good interface contact and barrier properties, while the region with higher carbon concentration provides the desired work function adjustment and reduces gate resistance.
2Reliability
If the work function adjustment film has high carbon concentration to reduce gate resistance, then gate resistance is improved, but threshold voltage control becomes difficult
Solution Approach 1:
The invention changes the carbon concentration parameter within the work function adjustment film to optimize both gate resistance and threshold voltage control. By establishing a carbon concentration gradient that increases from the barrier film interface toward the opposite side, the film achieves a balance between providing sufficient work function adjustment (for low gate resistance) and maintaining controllable threshold voltage characteristics.
3Ease of manufacture
If a uniform work function adjustment film is used to simplify manufacturing, then manufacturing complexity is reduced, but performance optimization is limited
Solution Approach 1:
The work function adjustment film is configured with a non-uniform carbon concentration distribution, where the carbon concentration increases from the interface with the barrier film toward the opposite side. This local variation in material composition allows different regions of the film to serve different functions: the region with lower carbon concentration near the barrier film maintains good interface contact and barrier properties, while the region with higher carbon concentration provides the desired work function adjustment and reduces gate resistance.
Solution Approach 2:
The invention changes the carbon concentration parameter within the work function adjustment film to optimize both gate resistance and threshold voltage control. By establishing a carbon concentration gradient that increases from the barrier film interface toward the opposite side, the film achieves a balance between providing sufficient work function adjustment (for low gate resistance) and maintaining controllable threshold voltage characteristics.
Data Source
AI summary
A semiconductor device and method for fabricating the same are provided. The semiconductor device includes a substrate, a first active pattern disposed on the substrate and spaced apart from the substrate, a gate insulating film which surrounds the first active pattern, a first work function adjustment film which surrounds the gate insulating film and includes carbon, and a first barrier film which surrounds the first work function adjustment film, in which a carbon concentration of the first work function adjustment film increases as it goes away from the first barrier film.