Fin Isolation Liner Composition for Oxidation and Etch Balance
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Solution Overview
Problem
The semiconductor industry faces challenges in protecting semiconductor fins from oxidation during processing and avoiding etch loading in the formation of shallow trench isolation (STI) regions, which affects the integration density and performance of FinFETs.
Innovation Solution
A silicon oxynitride liner with a controlled nitrogen concentration is used to protect the semiconductor fins from oxidation, and its composition is modified during processing to match the etch rate of the fill material, ensuring adequate oxidation resistance and reduced etch loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liner layer with high nitrogen concentration is used to protect fins from oxidation, then oxidation resistance is improved, but etch loading increases
Solution Approach 1:
The patent applies parameter changes by controlling the nitrogen concentration in the silicon oxynitride liner layer to be within a specific range (5% to 30%). This optimized parameter range allows the liner to provide sufficient oxidation protection while maintaining etch rate matching with the fill material, thereby reducing etch loading. The nitrogen concentration is the key parameter that is tuned to resolve the contradiction between oxidation resistance and etch loading.
Solution Approach 2:
The patent applies local quality by creating a liner layer with specific compositional characteristics (silicon oxynitride with controlled nitrogen content) that provides different properties at different locations: high oxidation resistance at the fin interface while maintaining appropriate etch selectivity in the isolation region. The localized compositional control enables simultaneous achievement of protection and reduced etch loading.
2Productivity
If integration density is increased by reducing minimum feature size, then more components can be integrated, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the nitrogen concentration in the liner layer, which enables better control over etch rates and oxidation protection. This improved process control allows for reduced minimum feature sizes while maintaining manufacturing precision, thereby increasing integration density without sacrificing quality.
Solution Approach 2:
The silicon oxynitride liner layer acts as an intermediary between the fin structure and the isolation fill material. It provides a controlled interface that manages both oxidation protection and etch rate matching, enabling precise manufacturing at smaller feature sizes required for higher integration density.
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 prevents oxidation of the fins and reduces etch loading, improving the integration density and electrical performance of FinFETs by maintaining optimal nitrogen concentration and etch selectivity.
Implementation Method 1
The silicon oxynitride has a nitrogen concentration that is selected to protect underlying features (e.g., semiconductor fins) from oxidation during subsequent processing
Implementation Method 2
an anneal can be performed. The liner has a sufficient nitrogen concentration to protect the semiconductor fins from oxidation during the anneal process
Data Source
AI summary
In an embodiment, a method includes: forming a first fin and a second fin extending from a semiconductor substrate; depositing a liner layer along a first sidewall of the first fin, a second sidewall of the second fin, and a top surface of the semiconductor substrate, the liner layer formed of silicon oxynitride having a nitrogen concentration; depositing a fill material on the liner layer, the fill material formed of silicon; annealing the liner layer and the fill material, the annealing converting the fill material to silicon oxide, the annealing decreasing the nitrogen concentration of the liner layer; and recessing the liner layer and the fill material to form an isolation region between the first fin and the second fin.