Segmented Gate Structure for Kink-Effect-Resistant Transistors
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Solution Overview
Problem
Modern integrated chips face performance degradation due to leakage currents and the kink effect caused by divots in shallow trench isolation structures, which affect threshold and sub-threshold voltages, leading to unpredictable device behavior.
Innovation Solution
A transistor device with a gate structure comprising multiple gate electrode regions of different work functions, where the source and drain regions have smaller widths than the channel region, and the gate structure extends over the channel region to separate it from the isolation structure edges, mitigating the impact of divots and dopant diffusion on threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the channel region is made narrow to increase device density, then the device size is reduced and density increases, but the kink effect and leakage currents increase due to proximity to isolation structure edges
Solution Approach 1:
The gate electrode is divided into multiple segments along the channel region, with each segment independently controllable. This segmentation allows different voltage biases to be applied to different regions, enabling suppression of the kink effect at isolation structure edges while maintaining high device density through narrow channel widths
Solution Approach 2:
Different regions of the gate electrode are assigned different electrical characteristics (voltage biases) to address local problems. Specifically, regions adjacent to isolation structures receive different biases than central channel regions, locally suppressing leakage currents and kink effects without affecting overall device performance
2Reliability
If the gate electrode is extended over the channel region to separate it from isolation structure edges, then the kink effect is reduced, but the device area increases
Solution Approach 1:
The gate electrode is segmented into multiple regions, allowing selective extension over the channel region only where needed near isolation structures. This targeted approach provides kink effect suppression without unnecessarily increasing overall device area in regions where isolation structures are absent
3Reliability
If multiple gate electrode regions with different work functions are used, then the kink effect is suppressed, but the manufacturing complexity increases
Solution Approach 1:
The work function of gate electrode regions is varied by changing material composition or thickness parameters. This allows different electrical characteristics to be achieved through controlled variations in physical parameters rather than fundamentally different structures, managing manufacturing complexity while suppressing the kink effect
Data Source
AI summary
An integrated chip comprises a substrate, an isolation structure and a gate structure. The isolation structure is disposed in the substrate and enclosing an active region in the substrate. The active region comprises a source region and a drain region separated by a channel region along a first direction. The gate structure is disposed over the channel region and comprising a first gate electrode region and a second gate electrode region arranged one next to another laterally along a second direction perpendicular to the first direction. The first gate electrode region has a first composition, and the second gate electrode region has a second composition different than the first composition.