MOSFET Isolation Gate Structure for Self-Aligned 3D Transistor Isolation
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Solution Overview
Problem
Existing semiconductor devices face challenges in integrating three-dimensional nanostructures, particularly in forming effective electrical isolation between adjacent transistors, which complicates processing and manufacturing, and requires advancements in IC processing and manufacturing techniques.
Innovation Solution
A self-aligned etching process is employed to form an isolation gate in MOSFET devices, using the interlayer dielectric layer and spacer sidewalls as etching mask elements to create a trench, followed by depositing material layers to achieve electrical isolation between adjacent circuits, thereby improving lithography friendliness and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a three dimensional transistor is introduced to replace a planar transistor, then functional density is increased, but processing and manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the interlayer dielectric layer and spacer sidewalls before the self-aligned etching process. These pre-formed structures serve as mask elements that automatically define the trench position, eliminating the need for separate alignment steps and reducing processing complexity while enabling three-dimensional transistor integration
Solution Approach 2:
The patent implements self-service through the self-aligned etching process where the interlayer dielectric layer and spacer sidewalls automatically serve as their own etching masks. The trench is formed precisely at the location where the mask elements are present, requiring no additional alignment operations and simplifying the manufacturing process
2Reliability
If a self-aligned etching process is used to form an isolation gate, then electrical isolation is enhanced, but processing steps are added
Solution Approach 1:
The patent merges multiple functions into the self-aligned etching process: the interlayer dielectric layer and spacer sidewalls simultaneously serve as both structural components and etching masks. This combination achieves electrical isolation between adjacent circuits while the self-aligned nature eliminates separate masking steps, so no additional processing steps are actually added
Solution Approach 2:
The patent applies multi-functionality by making the interlayer dielectric layer and spacer sidewalls serve dual purposes: they are both structural elements of the device and etching mask elements for trench formation. This universal use of existing structures achieves electrical isolation without requiring dedicated mask layers or additional processing 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 method enhances electrical isolation, improves device stability, increases chip speed, and ensures uniformity control over source/drain regions, while maintaining reliability and process margins without additional costs or area penalties.
Implementation Method 1
A self-aligned etching process is employed to form an isolation gate in MOSFET devices, using the interlayer dielectric layer and spacer sidewalls as etching mask elements to create a trench
Implementation Method 2
followed by depositing material layers to achieve electrical isolation between adjacent circuits
Data Source
AI summary
The present disclosure provides a semiconductor structure comprising one or more fins formed on a substrate and extending along a first direction; one or more gates formed on the one or more fins and extending along a second direction substantially perpendicular to the first direction, the one or more gates including an first isolation gate and at least one functional gate; source/drain features formed on two sides of each of the one or more gates; an interlayer dielectric (ILD) layer formed on the source/drain features and forming a coplanar top surface with the first isolation gate. A first height of the first isolation gate is greater than a second height of each of the at least one functional gate.