Semiconductor Gate Work Function Films for Threshold Voltage Control
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Solution Overview
Problem
Semiconductor devices face challenges in controlling threshold voltages (Vt) effectively as they are scaled down, requiring precise management of capacitance and electrical stability between elements and signal lines, which is not adequately addressed by current technologies.
Innovation Solution
The semiconductor device employs differently formed thicknesses and heights of work function films in gate structures for transistors across various regions, allowing for tailored threshold voltage control through varying thicknesses and heights of work function films and filling conductive films within recesses defined by these films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pitch size is decreased to achieve high integration and miniaturization, then device density and integration level are improved, but electrical stability between contacts and capacitance control deteriorate
Solution Approach 1:
The patent applies local quality by forming work function films with different thicknesses in different regions of the semiconductor device. Specifically, a first work function film is formed with a first thickness in a first region, and a second work function film is formed with a second thickness in a second region, allowing each region to have optimized electrical characteristics tailored to its specific functional requirements while maintaining high integration density
2Ease of manufacture
If uniform work function film thickness is used across all regions, then manufacturing simplicity is maintained, but threshold voltage control precision deteriorates
Solution Approach 1:
The patent implements local quality by creating region-specific work function film thicknesses to achieve precise threshold voltage control. The first work function film has a first thickness for transistors in the first region, while the second work function film has a second thickness for transistors in the second region, enabling independent optimization of electrical characteristics for different transistor types (e.g., NMOS and PMOS) without compromising manufacturing feasibility
Solution Approach 2:
The patent applies segmentation by dividing the semiconductor device into multiple regions (first region and second region) with distinct work function film characteristics. This segmentation allows each region to be independently optimized for its specific functional requirements, with the first work function film configured for transistors in the first region and the second work function film configured for transistors in the second region, thereby achieving precise threshold voltage control across different device regions
Data Source
AI summary
A semiconductor device is provided. The semiconductor device includes a substrate including a first region and a second region, a first gate structure extending in a first direction on the first region of the substrate, the first gate structure including a first gate insulation film and a first work function film disposed on the first gate insulation film, and a second gate structure extending in the first direction on the second region of the substrate, the second gate structure including a second gate insulation film and a second work function film disposed on the second gate insulation film, wherein a first thickness of the first work function film in a second direction intersecting the first direction is different from a second thickness of the second work function film in the second direction, and wherein a first height of the first work function film in a third direction perpendicular to the first and second directions is different from a second height of the second work function film in the third direction.