Source/Drain Silicide Contact Interface for Lower Resistance
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Solution Overview
Problem
The increasing critical dimension of metal lines and contacts in semiconductor devices leads to higher source/drain series resistance, with contact resistance becoming a critical factor in advanced technologies, necessitating a reduction in contact resistance to meet performance requirements.
Innovation Solution
Implanting dopants into the source/drain portions followed by rapid thermal anneal and laser anneal processes to increase dopant concentration at the interface, and reducing the Schottky barrier height between the source/drain portions and metal plugs to further decrease contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If critical dimension of metal lines and contacts is scaled down to increase device density, then device density is improved, but source/drain series resistance increases
Solution Approach 1:
The patent applies local quality by creating a transition layer with specific composition (e.g., SiGe, SiBC, or SiOC) at the contact interface between metal plug and source/drain region. This localized compositional modification reduces Schottky barrier height specifically at the contact interface without affecting other regions, thereby reducing contact resistance locally while maintaining overall device scaling
Solution Approach 2:
The patent changes physical and chemical parameters at the contact interface by introducing a transition layer with different material composition than the bulk source/drain region. The transition layer has tailored properties (composition, thickness, doping) that optimize electrical contact characteristics, resolving the resistance increase caused by scaling
2Reliability
If dopant concentration is increased at source/drain interface to reduce contact resistance, then contact resistance is reduced, but dopant diffusion and contamination risk increase
Solution Approach 1:
The transition layer acts as an intermediary between the metal plug and the source/drain region. It provides a controlled interface that facilitates electrical contact while preventing direct interaction between metal and dopants, thereby reducing contact resistance without the harmful effects of direct dopant diffusion into the metal
Solution Approach 2:
The contact structure is segmented into distinct layers: metal plug, transition layer, and source/drain region. This segmentation isolates the dopant-containing source/drain region from the metal plug, allowing high dopant concentration at the interface for low resistance while preventing dopant contamination of the metal through the barrier function of the transition layer
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 proposed method effectively reduces contact resistance by enhancing dopant concentration and lowering the Schottky barrier height, improving the electrical performance of semiconductor devices.
Implementation Method 1
Implanting dopants into the source/drain portions followed by rapid thermal anneal and laser anneal processes to increase dopant concentration at the interface
Implementation Method 2
followed by rapid thermal anneal and laser anneal processes
Data Source
AI summary
A semiconductor device includes a source/drain portion, a metal silicide layer disposed over the source/drain portion, and a transition layer disposed between the source/drain portion and the metal silicide layer. The transition layer includes implantation elements, and an atomic concentration of the implantation elements in the transition layer is higher than that in each of the source/drain portion and the metal silicide layer so as to reduce a contact resistance between the source/drain portion and the metal silicide layer. Methods for manufacturing the semiconductor device are also disclosed.