Work Function Metal Boundary Layout for High-k Gate Leakage Control
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Solution Overview
Problem
As the degree of integration of semiconductor memory elements increases, leakage current through the gate dielectric layer of transistors also increases, necessitating the use of high-k dielectric materials to mitigate this issue.
Innovation Solution
A semiconductor device is designed with a substrate having a cell region, a core region, and a boundary region, featuring a boundary element isolation layer, a high-k dielectric layer on the boundary element isolation layer and core region, and work function metal patterns with extensions of varying lengths overlapping the boundary element isolation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the degree of integration of semiconductor memory elements is increased, then the productivity and miniaturization are improved, but the leakage current through the gate dielectric layer increases causing reliability degradation
Solution Approach 1:
The device is divided into distinct regions: a cell region with conventional gates, a core region with high-k dielectric layers and work function metal patterns, and a boundary region with isolation layers. This segmentation allows the high-k dielectric structure to be applied selectively to the core region where leakage current is most problematic, without modifying the cell region structure, thereby improving reliability while maintaining high integration.
Solution Approach 2:
The high-k dielectric layer and work function metal pattern are applied locally to the core region rather than uniformly across the entire device. This local quality approach addresses the leakage current issue specifically in the core region where it occurs most severely, while leaving the cell region unchanged, thus improving reliability without sacrificing the productivity gains from high integration.
2Reliability
If a high-k dielectric layer is formed to reduce leakage current, then the reliability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The device structure is segmented into cell region, core region, and boundary region, with the high-k dielectric layer and work function metal pattern applied only to the core region. This segmentation simplifies the overall device complexity by limiting the complex high-k structure to where it is most needed, rather than applying it uniformly across the entire device.
Solution Approach 2:
A boundary element isolation layer is introduced as an intermediary structure between the cell region and core region. This isolation layer facilitates the transition between different device regions and enables the selective application of the high-k dielectric structure to the core region, thereby managing device complexity while achieving reliability improvement.
3Use of energy by moving object
If the core region is modified with high-k dielectric layer and work function metal pattern, then the power consumption is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The boundary element isolation layer serves as an intermediary that defines the transition zone between the cell region and core region. This isolation layer provides a clear reference structure for patterning the high-k dielectric layer and work function metal pattern, thereby establishing precise manufacturing boundaries and reducing the overall precision requirements for the complex high-k structure.
Solution Approach 2:
The boundary element isolation layer is formed in advance before the high-k dielectric layer and work function metal pattern are applied to the core region. This preliminary action establishes the spatial boundaries and reference structures needed for subsequent precise patterning operations, thereby reducing the manufacturing precision requirements for the high-k structure formation.
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 configuration improves the degree of integration and reliability of semiconductor devices by effectively managing leakage current and optimizing the use of high-k dielectric layers, while maintaining the structure of the bit line in the cell region.
Implementation Method 1
a gate dielectric layer is formed, using a high dielectric material (high-k dielectric material)
Data Source
AI summary
A semiconductor device and method for fabricating the same are provided. The semiconductor device includes a substrate including a cell region, a core region, and a boundary region between the cell region and the core region, a boundary element isolation layer in the boundary region of the substrate to separate the cell region from the core region, a high-k dielectric layer on at least a part of the boundary element isolation layer and the core region of the substrate, a first work function metal pattern comprising a first extension overlapping the boundary element isolation layer on the high-k dielectric layer, and a second work function metal pattern comprising a second extension overlapping the boundary element isolation layer on the first work function metal pattern, wherein a first length of the first extension is different from a second length of the second extension.