Source/Drain Silicide Structure for Multigate Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multigate devices, particularly gate-all-around (GAA) devices, face performance degradation due to the addition of multiple stacked channel layers, which complicates manufacturing processes and reduces device efficiency.
Innovation Solution
A method for fabricating multigate devices involving the formation of facets with a (111) crystallographic orientation in the source/drain regions, followed by the growth of epitaxial source/drain features and the introduction of a silicide feature to enhance contact formation and improve device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple stacked channel layers are added to GAA devices, then device functionality and current handling capability are improved, but manufacturing complexity and process difficulty increase
Solution Approach 1:
The source/drain structure is segmented into multiple discrete silicide regions, each aligned with specific channel layers. This segmentation allows independent optimization of contact regions for different channel stacks, simplifying the manufacturing process while maintaining support for multiple channel layers.
Solution Approach 2:
Silicide features are formed with locally optimized properties at different vertical positions. Upper silicide regions have different characteristics than lower silicide regions, allowing each region to be tailored for its specific function while maintaining overall device performance.
2Ease of manufacture
If conventional source/drain contact formation is used, then manufacturing process is simple, but contact resistance increases and device performance degrades
Solution Approach 1:
The contact formation process transitions from purely lateral patterning to include vertical dimensionality. Silicide features are formed at multiple vertical levels within the source/drain regions, enabling three-dimensional contact optimization that reduces resistance while maintaining manufacturing feasibility.
Solution Approach 2:
Multiple silicide features are nested within the source/drain regions at different vertical positions. This nested structure allows lower silicide regions to provide foundational contact while upper regions enhance current flow, creating a hierarchical contact system that reduces overall contact resistance.
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 method enhances gate control, reduces OFF-state current, and mitigates short-channel effects, thereby improving the performance and efficiency of multigate devices.
Implementation Method 1
growth of epitaxial source/drain features
Data Source
AI summary
Source/drain silicide that improves performance and methods for fabricating such are disclosed herein. An exemplary device includes a first channel layer disposed over a substrate, a second channel layer disposed over the first channel layer, and a gate stack that surrounds the first channel layer and the second channel layer. A source/drain feature disposed adjacent the first channel layer, second channel layer, and gate stack. The source/drain feature is disposed over first facets of the first channel layer and second facets of the second channel layer. The first facets and the second facets have a (111) crystallographic orientation. An inner spacer disposed between the gate stack and the source/drain feature and between the first channel layer and the second channel layer. A silicide feature is disposed over the source/drain feature where the silicide feature extends into the source/drain feature towards the substrate to a depth of the first channel layer.