Air Spacer Gate Structure for Semiconductor Isolation
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Solution Overview
Problem
As semiconductor device fabrication processes reduce feature sizes, electrical shorts between circuit elements become a challenge due to decreased distances between circuit elements, leading to process variations and reliability issues.
Innovation Solution
The method involves forming an active fin structure and isolation region on a substrate, followed by the creation of epitaxial layers, metal gate electrodes, and air spacers to provide electrical isolation between the gate and source/drain electrodes, using a replacement-metal-gate process and sacrificial spacer replacement with air spacers to enhance isolation and reduce shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are reduced to increase integration density, then integration density is improved, but electrical isolation between circuit elements deteriorates leading to shorts
Solution Approach 1:
The gate electrode structure is segmented into multiple metal layers (first metal gate electrode and second metal gate electrode) separated by an insulating layer. This segmentation provides internal electrical isolation within the gate structure itself, allowing reduced feature sizes while maintaining isolation between adjacent circuit elements through the layered configuration.
Solution Approach 2:
The patent transitions from a planar gate structure to a three-dimensional stacked gate structure with multiple metal layers separated by insulating layers. This dimensional change enables electrical isolation in the vertical dimension while maintaining horizontal integration density, effectively resolving the contradiction between size reduction and isolation maintenance.
2Productivity
If distances between circuit elements are reduced to increase density, then integration density is improved, but process variations increase causing electrical shorts
Solution Approach 1:
The gate electrode is divided into multiple segments (first and second metal gate electrodes) separated by an insulating layer. This segmentation allows each layer to be formed with independent process control, reducing the cumulative effect of process variations and enabling tighter spacing between circuit elements while maintaining manufacturing precision.
Solution Approach 2:
The insulating layer acts as an intermediary between the first and second metal gate electrodes, providing a controlled dielectric barrier that compensates for process variations. This intermediary layer ensures consistent electrical isolation and dimensional control, reducing variability in the final device characteristics.
3Device complexity
If conventional gate structures are used with reduced feature sizes, then fabrication complexity is reduced, but electrical shorts between gate and source/drain electrodes increase
Solution Approach 1:
The gate electrode is segmented into multiple metal layers with an insulating layer between them, creating a stacked configuration that provides inherent electrical isolation. This segmentation prevents direct electrical contact between the gate and source/drain electrodes, eliminating shorts while the standard sequential fabrication processes keep complexity manageable.
Solution Approach 2:
The gate electrode structure uses composite materials consisting of multiple metal layers (different conductive materials) separated by an insulating material. This composite structure provides both the electrical isolation needed to prevent shorts and the conductive properties needed for gate functionality, resolving the contradiction between simplicity and reliability.
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 reduces electrical shorts and improves the reliability of semiconductor devices by providing adequate electrical isolation between gate and source/drain electrodes, enhancing the density and performance of integrated circuits.
Implementation Method 1
Epitaxial layers is formed on the active fin structure
Data Source
AI summary
A method of fabricating a semiconductor device is provided as follows. Epitaxial layers is formed on an active fin structure of a substrate. First metal gate electrodes are formed on the active fin structure. Each first metal gate electrode and each epitaxial layer are alternately disposed in a first direction on the active fin structure. ILD patterns are formed on the epitaxial layers, extending in a second direction crossing the first direction. Sacrificial spacer patterns are formed on the first metal gate electrodes. Each of the plurality of sacrificial spacer patterns covers a corresponding first metal gate electrode of the first metal gate electrodes. Self-aligned contact holes and sacrificial spacers are formed by removing the ILD patterns. Each self-aligned contact hole exposes a corresponding epitaxial layer disposed under each ILD pattern. Source/drain electrodes are formed in the self-aligned contact holes. The sacrificial spacers are replaced with air spacers.