Lateral Source-Drain Epitaxy Confinement for Cell-Height Scaling
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Solution Overview
Problem
The scaling of multi-gate and nanowire transistors is limited by the constraints of lithographic processes, leading to a trade-off between feature dimension and spacing, which hinders further device density and performance optimization.
Innovation Solution
The implementation of confined epitaxial source-drain growth within a mold structure in gate-all-around and FinFET integrated circuit structures, allowing for customizable wingspan control of epitaxial source or drain structures through the use of a mold structure to define the lateral extent of these regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic processes are used to pattern transistor features, then manufacturing simplicity is maintained, but the critical dimension and spacing trade-off limits further scaling and device density
Solution Approach 1:
The mold structure is formed in advance before epitaxial growth, establishing predetermined lateral confinement boundaries. This preliminary structuring allows the epitaxial process to naturally define feature dimensions through the mold geometry rather than requiring complex lithographic patterning, thereby achieving precise critical dimensions while simplifying the lithographic process requirements
Solution Approach 2:
The mold structure serves as an intermediary element that mediates between the lithographic process and the final transistor features. By using the mold as a template during epitaxial growth, the system achieves precise feature definition without directly relying on high-resolution lithography, thus resolving the trade-off between manufacturing precision and process complexity
2Productivity
If transistor dimensions are reduced to increase device density, then capacity increases, but short channel control and mobility improvement become more difficult to maintain
Solution Approach 1:
The mold structure provides localized lateral confinement exactly where needed at the source-drain interface, creating non-uniform epitaxial growth that is confined in the lateral direction but extends vertically. This local quality control allows precise dimensional definition at critical regions while maintaining overall device scaling, thereby achieving high device density without sacrificing short channel control
Solution Approach 2:
The invention transitions from planar two-dimensional patterning to three-dimensional epitaxial growth constrained by vertical mold walls. By utilizing the vertical dimension for confinement rather than relying solely on lateral lithographic features, the system achieves precise dimensional control at scaled dimensions while maintaining short channel control through the vertical sidewall geometry
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
Enables increased transistor density and improved scalability by limiting the wingspan of epitaxial source or drain structures, enhancing short channel control and mobility, thereby optimizing device performance.
Implementation Method 1
confined epitaxial source-drain growth within a mold structure... use of a mold structure to define the lateral extent of these regions
Implementation Method 2
epitaxial source-drain growth... epitaxial source or drain structures
Data Source
AI summary
Gate-all-around integrated circuit structures having nanoribbon sub-fin isolation by backside Si substrate removal etch selective to source and drain epitaxy, are described. For example, an integrated circuit structure includes a plurality of horizontal nanowires above a sub-fin. A gate stack is over the plurality of nanowires and the sub-fin. Epitaxial source or drain structures are on opposite ends of the plurality of horizontal nanowires. The epitaxial growth occurs inside a mold confinement, and due the mold, the lateral wingspan of the wingspan of the epitaxial growth is limited. Also the mold causes the epitaxial source or drain structures to exhibit substantially vertical opposing sidewalls and a top surface having a generally mushroom shape over a top of a dielectric layer.