Gate Stack Passivation for SiGe FinFET Defect Reduction
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Solution Overview
Problem
As semiconductor devices approach smaller feature sizes, such as 5 nm or 3 nm technology nodes, they face challenges with interfacial and charge defects (Dit) that degrade performance, particularly when using materials like epitaxially grown silicon germanium, which boosts carrier mobility but introduces defects.
Innovation Solution
The process involves forming semiconductor fins with isolation regions, a dummy gate dielectric and electrode, and a passivation process using fluorine to reduce dangling bonds and defects in the n-metal work function layer, thereby minimizing aluminum diffusion and enhancing device performance without increasing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxially grown silicon germanium is used to boost carrier mobility, then device performance is improved, but interfacial and charge defects increase
Solution Approach 1:
A passivation layer is introduced as an intermediary between the silicon germanium fin and the n-metal work function layer. This passivation layer mediates the interface by reducing dangling bonds and preventing direct contact between defective surfaces, thereby reducing interfacial defects while preserving the high carrier mobility benefit of silicon germanium
Solution Approach 2:
The patent changes the chemical and physical parameters of the interface by applying a passivation treatment that modifies surface properties. This reduces the density of interface states and charge defects without altering the bulk properties of the silicon germanium that provide high carrier mobility
2Productivity
If feature size is reduced to increase integration density, then more components are integrated into a given area, but manufacturing precision requirements increase
Solution Approach 1:
The dummy gate dielectric and electrode are formed in advance before the actual gate structure is created. This preliminary action establishes a reference framework that guides subsequent patterning steps, enabling precise formation of smaller features while maintaining manufacturing control
Solution Approach 2:
The gate structure is divided into multiple components (dummy gate dielectric, dummy gate electrode, actual gate dielectric, actual gate electrode) formed in separate sequential steps. This segmentation allows each component to be optimized and controlled independently, facilitating precise manufacturing at smaller feature sizes
3Object-generated harmful factors
If a passivation process is applied to reduce defects, then interfacial and charge defects are reduced, but process complexity increases
Solution Approach 1:
The passivation process is merged with the existing gate dielectric formation step. The same deposition equipment and process conditions used for forming the gate dielectric are utilized to deposit the passivation layer, combining two functions into one process step and avoiding additional process complexity
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 reduces interfacial and charge defects, improves device performance, and maintains broad process windows without adding extra layers, especially beneficial for materials like silicon germanium that have higher defects.
Implementation Method 1
a passivation process using fluorine to reduce dangling bonds and defects in the n-metal work function layer, thereby minimizing aluminum diffusion
Data Source
AI summary
Semiconductor devices and methods of manufacturing semiconductor devices are provided. In embodiments a passivation process is utilized in order to reduce dangling bonds and defects within work function layers within a gate stack. The passivation process introduces a passivating element which will react with the dangling bonds to passivate the dangling bonds. Additionally, in some embodiments the passivating elements will trap other elements and reduce or prevent them from diffusing into other portions of the structure.