Nanostructure Transistor Source/Drain Growth on a Continuous Seed Layer
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Solution Overview
Problem
As semiconductor devices continue to shrink in size, defects and non-uniformity in source/drain regions become significant challenges, affecting device performance and yield.
Innovation Solution
The formation of source/drain regions on a continuous seed layer, with the use of inner spacers and a hard mask to protect nanostructures, enhances the uniformity and reduces defects, thereby improving device performance and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but defects and non-uniformity in source/drain regions increase
Solution Approach 1:
A seed layer is formed prior to the source/drain regions to provide a foundation that promotes uniformity. The seed layer is deposited and prepared in advance before the actual source/drain formation process, allowing it to establish a consistent base that guides subsequent material deposition and reduces defects in the final source/drain structures.
Solution Approach 2:
The seed layer acts as an intermediary between the substrate and the source/drain regions. This intermediate layer mediates the interface properties, ensuring better adhesion and more uniform characteristics in the source/drain regions that form on top of it, thereby reducing defects while maintaining small feature sizes.
2Productivity
If minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but device performance deteriorates due to defects
Solution Approach 1:
The seed layer is prepared in advance to establish a uniform foundation that prevents defects during source/drain formation. This preliminary preparation ensures that even at reduced feature sizes, the source/drain regions maintain the quality and uniformity needed for reliable device operation.
Solution Approach 2:
The seed layer serves as a mediating structure that protects the device performance by providing a controlled interface. This intermediary layer ensures that the source/drain regions form with fewer defects, maintaining device reliability despite the reduced feature sizes required for high integration density.
3Device complexity
If source/drain regions are formed without a seed layer to simplify the process, then manufacturing steps are reduced, but defects and non-uniformity increase
Solution Approach 1:
The seed layer is deposited as a preliminary step before source/drain formation. This early preparation creates a uniform base that guides subsequent material deposition, ensuring consistent source/drain region characteristics without requiring complex control during the actual formation process.
Solution Approach 2:
The seed layer acts as an intermediary that simplifies the overall process by providing a self-organizing foundation. Rather than requiring complex in-situ control during source/drain formation, the seed layer pre-establishes the conditions needed for uniform growth, reducing the need for additional manufacturing steps.
Data Source
AI summary
A method includes forming a stack of nanostructures over a substrate; forming a recess in the substrate adjacent the stack of nanostructures, wherein the recess exposes sidewalls of the stack of nanostructures; depositing a continuous semiconductor seed layer in the recess and extending along the sidewalls of the stack of nanostructures; epitaxially growing a source/drain region on the semiconductor seed layer; after epitaxially growing the source/drain region, forming inner spacers between adjacent nanostructures of the stack of nanostructures; and forming a gate structure between adjacent nanostructures of the stack of nanostructures.