FinFET Spacer Reshaping for Reliable Source/Drain Connections
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Solution Overview
Problem
The integration density of electronic components in semiconductor devices is limited by the challenge of forming reliable and low-resistance source/drain connections in FinFET devices, where the etch-through of source/drain regions during contact plug formation is a significant issue due to the small feature sizes and complex three-dimensional structures.
Innovation Solution
A pre-bake process is performed to reshape the spacers on opposing sides of the fins, curving their inner sidewalls to facilitate horizontal growth of epitaxial source/drain material, resulting in merged source/drain regions with increased volume, which enhances the connection with contact plugs and reduces the risk of etch-through during their formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but the formation of reliable source/drain connections becomes more difficult due to etch-through during contact plug formation
Solution Approach 1:
The patent performs a preliminary action by forming a mandrel structure and depositing spacer material before the actual source/drain region formation. This preliminary spacer formation establishes precise geometric constraints that prevent etch-through during subsequent contact plug formation, while still allowing high integration density through compact feature arrangement.
Solution Approach 2:
The patent introduces an intermediary spacer structure that acts as a protective mediator between the source/drain regions and the contact plug formation process. This spacer serves as a physical barrier that prevents direct etch access to the source/drain regions, thereby protecting connection reliability while enabling continued scaling for high integration density.
2Area of moving object
If the feature size is reduced to increase integration density, then more components fit in a given area, but the source/drain regions become thinner and more susceptible to etch-through
Solution Approach 1:
The patent applies local quality by creating spacers with different properties at different locations - the spacers have specific thicknesses and material compositions tailored to the local requirements of each source/drain region. This allows precise control of source/drain region thickness in high-density areas while maintaining manufacturing precision through localized spacer characteristics.
Solution Approach 2:
The patent utilizes parameter changes by varying the spacer material composition, thickness, and deposition conditions to achieve the desired source/drain region dimensions. By adjusting these parameters, the patent maintains precise thickness control even as overall feature sizes are reduced for higher integration density.
3Ease of manufacture
If conventional spacer formation is used in high-density FinFET structures, then the fabrication process remains simple, but the spacers cannot provide sufficient protection against etch-through of source/drain regions
Solution Approach 1:
The patent applies segmentation by dividing the spacer formation into multiple distinct steps - first forming initial spacers, then forming additional spacers with different materials or properties. This segmented approach maintains relative fabrication simplicity while providing enhanced, multi-layered protection against etch-through in high-density FinFET structures.
Solution Approach 2:
The patent employs composite materials by using different spacer materials in sequence or combination - such as combining silicon nitride, silicon oxide, or other dielectric materials. This composite spacer structure provides superior protection against etch-through compared to conventional single-material spacers, while the processes remain compatible with existing fabrication workflows.
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 solution achieves reliable connections with lower contact resistance and prevents etch-through of source/drain regions, improving the production yield and device performance by ensuring thicker, more robust source/drain regions.
Implementation Method 1
treating the first spacers using a baking process
Implementation Method 2
epitaxially growing a first semiconductor material over a top surface of the first fin
Data Source
AI summary
A method includes forming first spacers on opposing sidewalls of a first fin, where the first fin protrudes above a substrate, recessing the first fin to form a first recess between the first spacers, and treating the first spacers using a baking process, where treating the first spacers changes a profile of the first spacers. The method further includes epitaxially growing a first semiconductor material over a top surface of the first fin after treating the first spacers.