TiN-Co Contact Trench Stack for Low-Resistance FinFET Contacts
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Solution Overview
Problem
Existing methods for forming contact metal in FinFET devices face challenges in reducing contact resistance and achieving good adhesion and conformity, especially as devices scale down, leading to increased complexity and inefficiency in IC processing and manufacturing.
Innovation Solution
A method involving the formation of a titanium nitride (TiN) adhesion layer followed by a cobalt (Co) metal layer within the contact trench, using atomic layer deposition (ALD) to enhance adhesion and electromigration resistance, resulting in a robust and low-resistance contact metal formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods are used for forming contact metal in FinFET devices, then the process is simpler, but contact resistance is high and adhesion is poor
Solution Approach 1:
The contact metal formation process is segmented into multiple sequential deposition steps: first depositing a titanium nitride adhesion layer, then depositing a cobalt metal layer, and finally performing a silicidation step. This segmentation allows each layer to perform its specific function optimally, improving overall contact quality without requiring a single complex material
Solution Approach 2:
The patent employs a composite structure consisting of titanium nitride (TiN) as the adhesion layer and cobalt (Co) as the metal layer. This composite material approach combines the high adhesion properties of TiN with the low resistance and electromigration resistance properties of Co, achieving superior contact performance that neither material could provide alone
2Productivity
If device geometry is scaled down to increase functional density, then production efficiency increases, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes atomic layer deposition (ALD) process parameters to achieve precise thickness control of the titanium nitride adhesion layer and cobalt metal layer. By optimizing deposition parameters such as temperature, pressure, and precursor flow rates, the process achieves conformal coverage in scaled-down FinFET structures while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces traditional physical vapor deposition methods with atomic layer deposition (ALD), which uses chemical vapor deposition mechanisms to achieve atomic-level precision in thin film formation. This substitution enables better control over film thickness and conformity in scaled-down devices, reducing manufacturing complexity despite the advanced process requirements
3Reliability
If a single metal layer is used for contact formation, then the process is simpler, but adhesion and electromigration resistance are insufficient
Solution Approach 1:
The contact structure is segmented into functionally distinct layers: the titanium nitride layer provides adhesion and electromigration resistance, while the cobalt layer provides low resistance and catalytic properties for silicidation. This functional segmentation achieves superior reliability without requiring overly complex manufacturing
Solution Approach 2:
The titanium nitride layer acts as an intermediary between the underlying semiconductor structure and the cobalt metal layer. It provides the necessary adhesion interface and protects against electromigration, while allowing the cobalt layer to perform its electrical function effectively. This intermediary layer resolves the conflict between adhesion requirements and electrical performance
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 contact resistance and improves adhesion and conformity of the metal layer within the contact trench, addressing the scaling challenges and enhancing device performance, particularly in advanced technology nodes of integrated circuits.
Implementation Method 1
using atomic layer deposition (ALD) to enhance adhesion and electromigration resistance
Data Source
AI summary
A semiconductor device is disclosed. The device includes a source/drain feature formed over a substrate. A dielectric layer formed over the source/drain feature. A contact trench formed through the dielectric layer to expose the source/drain feature. A titanium nitride (TiN) layer deposited in the contact trench and a cobalt layer deposited over the TiN layer in the contact trench.