T-Shaped Transistor Gate Structure for Lower Off-Current
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Solution Overview
Problem
Existing transistor devices face challenges in reducing off-current (Ioff) and power consumption while maintaining electrical performance.
Innovation Solution
A transistor structure with a gate dielectric layer located between the first and second portions of the gate, and between the gate and isolation structure, featuring a T-shaped cross-section and U-shaped dielectric layer configuration, which prevents corner thinning and includes a spacer on the sidewalls, enhancing the electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gate width is reduced to lower off-current, then power consumption decreases, but the subthreshold hump effect increases due to corner thinning of the gate dielectric layer
Solution Approach 1:
The gate dielectric layer is configured with different thicknesses in different regions: a first thickness in the corner region and a second thickness in the non-corner region, where the first thickness is greater than the second thickness. This local quality differentiation prevents corner thinning while maintaining the overall gate width reduction, thereby reducing off-current without introducing subthreshold hump effect
Solution Approach 2:
The gate structure transitions from a conventional planar configuration to a T-shaped cross-section configuration, adding vertical dimensionality with the gate extending over the isolation structure. This dimensional change allows the gate dielectric layer to be positioned strategically to prevent corner thinning while maintaining effective gate control, thus reducing off-current without compromising reliability
2Loss of energy
If the gate width is reduced to reduce off-current, then power consumption decreases, but electrical performance deteriorates
Solution Approach 1:
The gate is divided into a first gate portion and a second gate portion, where the first gate portion is positioned over the active region and the second gate portion extends over the isolation structure. This segmentation allows the gate to maintain effective control over the channel (preserving electrical performance) while the overall structure enables reduced off-current and power consumption
Solution Approach 2:
The gate dielectric layer has different thicknesses in different regions, with the first thickness in the corner region being greater than the second thickness in the non-corner region. This local quality enhancement maintains electrical performance by preventing corner thinning while allowing overall gate width reduction for lower power consumption
Data Source
AI summary
A transistor structure including a substrate, an isolation structure, a gate, and a gate dielectric layer is provided. The isolation structure is located in the substrate. The isolation structure defines an active region in the substrate. The isolation structure protrudes from a top surface of the substrate to form a recess above the active region. The gate is located on the substrate. The gate includes a first portion and a second portion. The first portion is located in the recess. The second portion is located on the first portion. The second portion is located directly above a portion of the isolation structure. The gate dielectric layer is located between the first portion and the substrate, between the first portion and the isolation structure, and between the second portion and the isolation structure.