Source/Drain Contact Structure With NiSi2 Silicide Against Metal Spiking
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, challenges such as electrical shorts due to metal spiking and undesirable threshold voltage shifts arise, particularly in the formation of silicide regions for source/drain contacts.
Innovation Solution
The use of a pre-silicide layer allows for the formation of a NiSi2 silicide region at lower anneal temperatures, reducing the risk of electrical shorts and threshold voltage shifts, while also improving contact resistance and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicide formation processes are used, then source/drain contacts can be formed, but electrical shorts due to metal spiking and threshold voltage shifts occur
Solution Approach 1:
A nickel silicide layer is formed on the source/drain regions before the final contact formation process. This preliminary silicide layer acts as a protective barrier that prevents metal spiking into the channel region during subsequent high-temperature annealing processes, thereby preventing electrical shorts and threshold voltage shifts while allowing the final contact to be formed at controlled temperatures
Solution Approach 2:
The nickel silicide layer serves as an intermediary layer between the source/drain regions and the metal contact. This intermediate layer mediates the interaction by providing a stable interface that prevents direct contact between the metal and the semiconductor channel, eliminating the harmful metal spiking effect while maintaining good electrical contact properties
2Reliability
If higher anneal temperatures are used to form silicide regions, then better contact resistance is achieved, but metal spiking and threshold voltage shifts increase
Solution Approach 1:
The nickel silicide layer is formed in advance on the source/drain regions before depositing the metal contact. This preliminary formation creates a stable, low-resistance interface that allows for effective contact formation at moderate anneal temperatures, eliminating the need for excessively high temperatures that would cause metal spiking
Solution Approach 2:
The nickel silicide layer acts as an intermediary that enables good electrical contact without requiring high-temperature processing. It provides a stable interface with low contact resistance while physically blocking the metal from spiking into the channel region during annealing
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 described technique enables the formation of NiSi2 silicide regions with improved resistance and reduced contact resistance, while minimizing the risk of thermal-related issues such as metal spiking and threshold voltage shifts.
Implementation Method 1
depositing a nickel layer on the source/drain regions, and annealing the nickel layer to react a portion of the semiconductor region below the nickel layer with the nickel to form a NiSi2 silicide region
Implementation Method 2
annealing the nickel layer to react a portion of the semiconductor region below the nickel layer with the nickel to form a NiSi2 silicide region
Implementation Method 3
react a portion of the semiconductor region below the nickel layer with the nickel to form a NiSi2 silicide region
Data Source
AI summary
A device includes a fin extending from a semiconductor substrate, a gate stack over and along a sidewall of the fin, an isolation region surrounding the gate stack, an epitaxial source/drain region in the fin and adjacent the gate stack, and a source/drain contact extending through the isolation region, including a first silicide region in the epitaxial source/drain region, the first silicide region including NiSi2, a second silicide region on the first silicide region, the second silicide region including TiSix, and a conductive material on the second silicide region.