Fin Structure Formation Using Silicon Carbon Nitride Shell
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Solution Overview
Problem
Traditional planar semiconductor devices face challenges such as short-channel effects and poor sub-threshold characteristics as feature sizes shrink, prompting the need for more advanced non-planar structures like FinFETs, which often result in rough surfaces due to channel-reshape processes affecting device performance.
Innovation Solution
The formation of fin structures involves depositing a shell material like silicon carbon nitride using plasma-enhanced atomic layer deposition to protect and define the size of fin structures, followed by epitaxial growth of channel materials and chemical-mechanical planarization to achieve desired dimensions, while using etching and CMP processes to refine the structures and smooth surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel-reshape processes are used to form FinFET structures, then device performance is improved, but surface roughness increases affecting device performance
Solution Approach 1:
The patent applies preliminary action by forming a mandrel structure and shell material before creating the final fin structure. The mandrel is formed with controlled dimensions, and the shell material is deposited to define the fin size, ensuring surface smoothness is established early in the process before subsequent etching steps.
Solution Approach 2:
The patent uses an intermediary approach by introducing a shell material layer that acts as a mediator between the mandrel structure and the final fin structure. This shell material (such as silicon carbon nitride) protects the mandrel during etching and defines the fin dimensions, resulting in smooth fin surfaces while maintaining the desired geometric profile.
2Productivity
If feature sizes are shrunk to increase packing density, then device integration is improved, but short-channel effects and poor sub-threshold characteristics occur
Solution Approach 1:
The patent applies dimensionality change by transitioning from planar device structures to three-dimensional FinFET structures. The vertical fins provide additional channel control through the gate, improving sub-threshold characteristics and reducing short-channel effects while enabling smaller feature sizes and higher packing densities.
Solution Approach 2:
The patent uses parameter changes by modifying the geometric parameters of the device structure - creating vertical fins with specific width, length, and depth dimensions. The shell material thickness and etching parameters are carefully controlled to achieve the desired fin geometry that balances packing density with electrical performance.
3Manufacturing precision
If shell material is deposited to protect and define fin structures, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent applies universality by designing the shell material to perform multiple functions simultaneously: it protects the mandrel structure during etching, defines the fin dimensions, and provides a release layer that enables clean removal of the mandrel. This multi-functionality reduces the need for separate protective and defining steps.
Solution Approach 2:
The patent uses composite materials by selecting shell material with specific properties - such as silicon carbon nitride - that combines protective characteristics, etch selectivity, and release properties. This composite approach allows a single material layer to fulfill multiple process requirements, simplifying the overall fabrication sequence.
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 enables the fabrication of fin structures with improved surface smoothness and controlled dimensions, enhancing device performance by reducing roughness and achieving desired feature sizes, thus addressing the limitations of traditional planar devices.
Implementation Method 1
depositing a shell material like silicon carbon nitride using plasma-enhanced atomic layer deposition
Implementation Method 2
followed by epitaxial growth of channel materials
Data Source
AI summary
Structures and methods are provided for forming fin structures. A first fin structure is formed on a substrate. A shallow-trench-isolation structure is formed surrounding the first fin structure. At least part of the first fin structure is removed to form a cavity. A first material is formed on one or more side walls of the cavity. A second material is formed to fill the cavity, the second material being different from the first material. At least part of the STI structure is removed to form a second fin structure including the first material and the second material. At least part of the first material that surrounds the second material is removed to fabricate semiconductor devices.