Semiconductor Protection Layer for FinFET Source/Drain Oxidation
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Solution Overview
Problem
As semiconductor devices, such as FinFETs, undergo manufacturing processes, the source/drain regions are prone to damage, particularly oxidation, during the formation of interlayer dielectric layers, which can lead to reliability and reproducibility issues due to the need for thicker etch stop layers to prevent damage.
Innovation Solution
A protection layer, typically silicon oxynitride, is formed over the source/drain regions, which can be annealed to reduce nitrogen content, allowing for a thinner contact etch stop layer and easier etching, while preventing oxidation during subsequent processing steps without compromising contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker etch stop layer is used to prevent oxidation of source/drain regions, then reliability is improved, but manufacturing precision deteriorates due to difficulties in contact formation
Solution Approach 1:
The patent divides the protective layering into multiple functional segments: a thin contact etch stop layer (20-50 nm) for precise contact formation, and a separate thicker protection layer (50-200 nm) for oxidation prevention. This segmentation allows each layer to optimize its thickness for its specific function, resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The patent introduces an intermediate protection layer formed between the contact etch stop layer and the interlayer dielectric. This intermediate layer acts as a mediator that provides oxidation protection during subsequent processing steps while allowing the thinner contact etch stop layer to enable precise contact formation, thus resolving the contradiction.
2Object-affected harmful factors
If a thicker protection layer is formed over source/drain regions, then oxidation damage is reduced, but etching difficulty increases
Solution Approach 1:
The patent changes the material composition parameter of the protection layer by forming it as silicon oxynitride with controlled oxygen and nitrogen ratios. This parameter change provides oxidation protection while maintaining etchability through selective etching processes that exploit the specific material properties of silicon oxynitride, thus resolving the contradiction between protection and etching ease.
Solution Approach 2:
The patent uses silicon oxynitride as a composite material that combines the oxidation protection properties of silicon oxide with the etchability enhancements provided by nitrogen incorporation. This composite material provides both oxidation damage reduction and manageable etching characteristics, resolving the contradiction between protection and manufacturing ease.
3Productivity
If minimum feature size is reduced to increase integration density, then productivity is improved, but manufacturing precision deteriorates due to increased susceptibility to damage
Solution Approach 1:
The patent applies preliminary protective action by forming the contact etch stop layer and protection layer before subsequent processing steps that could cause damage. This preliminary protection allows smaller features to be manufactured with higher precision by preventing oxidation and damage during processing, thus resolving the contradiction between increased integration density and feature damage control.
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
The protection layer effectively reduces damage to source/drain regions, enables the use of thinner etch stop layers, and improves the reproducibility and reliability of contact formation in semiconductor devices, while allowing for easier etching and reduced oxidation risks.
Implementation Method 1
forming a protection layer over the source/drain regions, which can be annealed to reduce nitrogen content
Implementation Method 2
annealed to reduce nitrogen content, allowing for a thinner contact etch stop layer and easier etching
Implementation Method 3
preventing oxidation during subsequent processing steps without compromising contact formation
Data Source
AI summary
A method includes forming a fin extending from a substrate; forming an first isolation region along opposing sidewalls of the fin; forming a gate structure over the fin; forming an epitaxial source/drain region in the fin adjacent the gate structure; forming an etch stop layer over the epitaxial source/drain region and over the gate structure; forming a protection layer over the etch stop layer, the protection layer including silicon oxynitride; and forming a second isolation material over the protection layer, wherein forming the second isolation material reduces a nitrogen concentration of the protection layer.