FinFET Epitaxial Layer Protection via Nitrogen Dielectric Cap
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Solution Overview
Problem
The integration of fin-shaped structures and epitaxial layers in FinFET fabrication leads to current leakage and performance issues, necessitating improvements in the current FinFET process.
Innovation Solution
A method involving the formation of a first contact etch stop layer (CESL) on an epitaxial layer, followed by a cap layer and a second CESL, which replaces the conventional silicon oxide cap layer to prevent surface damage during ion implantation and enhance device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional silicon oxide cap layer is used on the epitaxial layer, then the epitaxial layer is protected during processing, but surface damage occurs during ion implantation requiring damaging cleaning agents like diluted hydrofluoric acid
Solution Approach 1:
The patent changes the material parameter of the cap layer from conventional silicon oxide to a nitrogen-containing dielectric material (such as silicon nitride or silicon oxynitride). This material substitution alters the interaction between the cap layer and ion implantation processes, preventing surface damage to the epitaxial layer while maintaining protective functions during subsequent processing steps.
Solution Approach 2:
The nitrogen-containing dielectric cap layer serves as an intermediary between the ion implantation process and the epitaxial layer. Instead of allowing direct damage to the epitaxial layer surface, this intermediate layer absorbs or deflects the harmful effects of ion implantation, eliminating the need for aggressive cleaning agents like diluted hydrofluoric acid that would otherwise be required to remove damaged surfaces.
2Area of moving object
If the FinFET structure is scaled down to reduce device size, then integration density increases, but current leakage and performance issues worsen
Solution Approach 1:
The patent introduces nitrogen-containing dielectric materials with specific electrical properties that differ from conventional silicon oxide. These materials provide better electrical isolation and control characteristics that prevent current leakage in scaled-down FinFET structures, maintaining device performance despite reduced dimensions.
Solution Approach 2:
The use of nitrogen-containing dielectric materials represents a composite approach to cap layer design, combining dielectric properties with nitrogen incorporation to achieve both mechanical protection and electrical control. This composite material structure addresses multiple performance requirements simultaneously in miniaturized devices.
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 reduces current leakage and improves overall device performance by eliminating the need for damaging cleaning agents like diluted hydrofluoric acid, allowing for precise control of the FinFET structure and operation.
Implementation Method 1
forming an epitaxial layer on the fin-shaped structure
Implementation Method 2
replaces the conventional silicon oxide cap layer to prevent surface damage during ion implantation
Data Source
AI summary
A method for fabricating semiconductor device is disclosed. The method includes the steps of: providing a substrate having a fin-shaped structure thereon; forming an epitaxial layer on the fin-shaped structure; forming a first contact etch stop layer (CESL) on the epitaxial layer; forming a source/drain region in the epitaxial layer; and forming a second CESL on the first CESL.