Segmented Gate Dielectric Structure for Threshold Voltage Isolation
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Solution Overview
Problem
As integrated circuits scale down, the proximity of semiconductor devices leads to issues such as cross contamination and threshold voltage shifts due to diffusion of dopants like La between different threshold voltage devices, affecting device performance and reliability.
Innovation Solution
The implementation of a semiconductor device structure with separate gate dielectric layers for different threshold voltage devices, using work function adjustment material layers and high-k dipole layers, and a method to suppress dopant diffusion by forming a trench between these layers, filled with a conductive or dielectric material to act as a barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integrated circuits are scaled down to increase device density, then device integration is improved, but dopant diffusion between nearby devices causes threshold voltage shifts and performance degradation
Solution Approach 1:
The gate dielectric layer is segmented into separate regions for different threshold voltage devices, with an intervening trench structure physically dividing the dielectric layer between adjacent devices. This segmentation prevents dopant diffusion while maintaining high device density.
Solution Approach 2:
An intervening trench structure filled with dielectric material or conductive filler acts as an intermediary barrier between adjacent threshold voltage devices. This intermediate structure blocks dopant diffusion paths while allowing both devices to function at high integration density.
2Productivity
If different threshold voltage devices are placed close together to increase density, then device integration is improved, but cross contamination between devices increases
Solution Approach 1:
The gate dielectric layer is divided into separate regions for different threshold voltage devices, with an intervening trench structure physically separating the dielectric layers. This segmentation eliminates cross contamination while maintaining high device integration.
Solution Approach 2:
The harmful dopant diffusion path is extracted or removed by introducing an intervening trench structure that physically separates adjacent devices. This extraction of the diffusion path prevents cross contamination between devices.
3Reliability
If dopant diffusion is prevented by increasing spacing between devices, then threshold voltage stability is improved, but device integration decreases
Solution Approach 1:
Instead of increasing horizontal spacing between devices, the solution introduces a vertical dimension by etching an intervening trench and filling it with barrier material. This dimensional change blocks dopant diffusion without sacrificing horizontal device density.
Solution Approach 2:
An intervening trench structure serves as a mediator that blocks dopant diffusion between adjacent devices while occupying minimal space. This intermediate structure enables both high integration and threshold voltage stability.
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
This approach effectively prevents dopant diffusion, maintaining device performance and reliability by isolating gate dielectric layers with different dopant concentrations, thereby stabilizing threshold voltages across nearby devices.
Implementation Method 1
a method to suppress dopant diffusion by forming a trench between these layers, filled with a conductive or dielectric material to act as a barrier
Data Source
AI summary
A gate structure of a field effect transistor includes a first gate dielectric layer, a second gate dielectric layer, and one or more conductive layers disposed over the first gate dielectric layer and the second gate dielectric layer. The first gate dielectric layer is separated from the second gate dielectric layer by a gap filled with a diffusion blocking layer.