FinFET Source/Drain Spacer Profiling for Strain and Contact Resistance
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Solution Overview
Problem
Current methods for forming source and drain features in FinFETs lack the ability to independently control strain effect and contact resistance, which are crucial for different design requirements, leading to suboptimal device performance.
Innovation Solution
The method involves forming epitaxial source and drain features by controlling the height of fin sidewall spacers through two patterning and two distinct etching processes, allowing for varying shapes and dimensions to enhance strain effect and reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods are used to form source and drain features in FinFETs, then the basic device structure is achieved, but the ability to independently control strain effect and contact resistance is lost
Solution Approach 1:
The fabrication process is divided into two separate etching processes: a first etching process that forms initial source/drain features, and a second etching process that forms additional source/drain features with different characteristics. This segmentation allows independent control of strain effect and contact resistance, as each etching process can be optimized for its specific purpose without being constrained by the other.
Solution Approach 2:
The first etching process performs preliminary formation of source/drain features to establish the basic structure and induce strain in the channel region. Subsequently, the second etching process adds additional source/drain features to optimize contact resistance. This preliminary action approach allows each process step to build upon the previous one, achieving multiple objectives sequentially.
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 increases carrier mobility and enhances device performance by optimizing strain effects and contact resistance, providing more design freedom for different FinFET configurations.
Implementation Method 1
forming epitaxial source and drain features
Data Source
AI summary
A method includes forming a first portion of a spacer layer over a first fin and a second portion of the spacer layer over a second fin, performing a first etching process to recess the first portion of the spacer layer with respect to the second portion of the spacer layer to form first spacers on sidewalls of the first fin, subsequently performing a second etching process to recess the second portion of the spacer layer with respect to the first spacers to form second spacers on sidewalls of the second fin, where the second spacers are formed to a height greater than that of the first spacers, and forming a first epitaxial source/drain feature and a second epitaxial source/drain feature between the first spacers and the second spacers, respectively, where the first epitaxial source/drain feature is larger than that of the second epitaxial source/drain feature.