Dummy Gate Overlap on Isolation Regions to Prevent MOSFET Leakage
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Solution Overview
Problem
The scaling down of semiconductor devices, such as MOSFETs, leads to challenges with device packing density and performance due to leakage issues caused by improperly formed epitaxial features adjacent to dummy gates, resulting in asymmetric electrical properties and undesired dopant distribution.
Innovation Solution
The configuration of semiconductor devices is adjusted by forming a wider dummy gate that overlaps with the isolation region, preventing exposure of the isolation region during epitaxial growth and ensuring proper formation of epitaxial features, which improves device performance and reduces leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the dummy gate is formed with the same width as the active region, then the fabrication process is simple, but the epitaxial features are improperly formed and leakage occurs
Solution Approach 1:
The dummy gate width is changed from being equal to the active region width to being wider than the active region width. This parameter change ensures that the dummy gate fully covers the isolation region, preventing epitaxial material from contacting the isolation region and forming improper epitaxial features, thereby eliminating leakage while maintaining fabrication simplicity
Solution Approach 2:
The dummy gate is designed with extended width in advance to cover the isolation region before epitaxial growth occurs. This preliminary structural configuration prevents the harmful contact between epitaxial material and isolation region during the growth process, avoiding improper epitaxial feature formation and subsequent leakage issues
2Manufacturing precision
If the dummy gate overlaps with the isolation region, then epitaxial features are properly formed, but the device structure becomes more complex
Solution Approach 1:
The dummy gate width parameter is increased to create overlap with the isolation region. This single parameter change achieves proper epitaxial feature formation by preventing epitaxial material contact with the isolation region, while the structural complexity increase is minimal since it only involves extending the gate width without adding new components or process steps
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 enhances the uniformity and volume of epitaxial features, leading to improved device performance with symmetric cross-section profiles and reduced leakage issues by preventing direct contact between epitaxial features and the isolation region during growth.
Implementation Method 1
preventing exposure of the isolation region during epitaxial growth and ensuring proper formation of epitaxial features
Data Source
AI summary
The present disclosure provides a semiconductor device, including a substrate, a first active region in the substrate, a second active region in the substrate and adjacent to the first active region, an isolation region in the substrate and between the first active region and the second active region, and a dummy gate overlapping with the isolation region, wherein an entire bottom width of the dummy gate is greater than an entire top width of the isolation region.