Metal Gate Modulation for Kink Effect Mitigation
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Solution Overview
Problem
Modern integrated chips face issues with leakage currents and the kink effect due to divots in shallow trench isolation structures, which affect transistor device performance and make it difficult to model and maintain threshold voltage.
Innovation Solution
A transistor device with a gate structure comprising multiple gate electrode regions of different work functions is used, where one gate electrode region is disposed over the divots in the isolation structure, mitigating the kink effect by offsetting the impact of divots and dopant diffusion on threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single work function gate electrode is used, then the device structure is simple, but the threshold voltage cannot be maintained consistently due to kink effect from divots and dopant diffusion
Solution Approach 1:
The gate electrode is divided into multiple regions with different work functions, where each region is positioned over specific areas (such as over divots or lightly-doped regions) to provide localized threshold voltage adjustment. This allows the gate to compensate for local variations caused by divots and dopant diffusion, maintaining consistent threshold voltage across the device while addressing the kink effect through spatially differentiated material properties.
2Productivity
If device dimensions are reduced to increase density, then productivity and power efficiency improve, but the kink effect becomes more pronounced due to increased sensitivity to divots and dopant diffusion
Solution Approach 1:
The invention changes the work function parameter of the gate electrode material in different regions to compensate for the increased sensitivity to divots and dopant diffusion in scaled devices. By adjusting the work function locally (using different metal compositions or alloys in different gate regions), the threshold voltage can be maintained despite the heightened kink effect in smaller, denser devices, thereby enabling continued scaling while maintaining 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
The solution effectively reduces the susceptibility to the kink effect, improving transistor device performance by maintaining a consistent threshold voltage and reducing cross-talk between adjacent devices.
Implementation Method 1
A transistor device with a gate structure comprising multiple gate electrode regions of different work functions is used, where one gate electrode region is disposed over the divots in the isolation structure, mitigating the kink effect by offsetting the impact of divots and dopant diffusion on threshold voltage
Data Source
AI summary
The present disclosure relates to an integrated chip. The integrated chip includes a source region and a drain region disposed within an upper surface of a substrate. One or more dielectric materials are disposed within a trench defined by sidewalls of the substrate that surround the source region and the drain region. The one or more dielectric materials include one or more interior surfaces defining a recess within the one or more dielectric materials. A gate structure is disposed over the substrate between the source region and the drain region. The gate structure includes a first gate material over the upper surface of the substrate and a second gate material. The second gate material completely fills the recess as viewed along a cross-sectional view.