Selective Titanium Silicide Contacts With TiSixNy Sidewall Lining
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to issues with defect formation and performance reduction due to the use of heterogeneous conductive materials, which can result in solid solutioning, galvanic corrosion, and increased parasitic capacitance, especially when different types of metals are interfaced, and existing barrier layers can increase sheet resistance and reduce available space for conductive structures.
Innovation Solution
The formation of homogenous conductive structures using a titanium precursor to selectively form a titanium silicide layer on source/drain regions, followed by a plasma-based deposition process that creates a silicon-rich surface, allowing for the formation of titanium silicon nitride on sidewalls without additional barrier layers, and using the same conductive material for source/drain interconnects to reduce defects and parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heterogeneous conductive materials are used in conductive structures, then electrical connectivity is achieved, but defect formation increases due to solid solutioning and galvanic corrosion
Solution Approach 1:
The patent applies homogeneity by using the same conductive material (e.g., cobalt, tungsten, or ruthenium) for both the conductive structure and the liner layer, eliminating material interfaces that cause solid solutioning and galvanic corrosion. This single-material approach ensures uniform electrical and physical properties throughout the conductive structure, preventing defect formation at material boundaries.
Solution Approach 2:
The patent extracts and eliminates the traditional barrier/liner layer from the conductive structure by demonstrating that the conductive material itself can function without an additional protective layer. This removal simplifies the structure to a single homogeneous material system, eliminating the interfaces that cause reliability issues.
2Reliability
If barrier layers are added to conductive structures, then material diffusion is prevented, but sheet resistance increases and available space is reduced
Solution Approach 1:
The patent removes the barrier/liner layer entirely from the conductive structure, demonstrating that the conductive material can be deposited directly without an additional protective layer. This extraction eliminates the sheet resistance contribution from the barrier layer and maximizes the available space for the conductive material.
Solution Approach 2:
By using a single homogeneous conductive material without an intervening barrier layer, the patent ensures optimal electrical conductivity throughout the structure. The uniform material composition minimizes sheet resistance compared to multi-layer heterogeneous structures.
3Adaptability or versatility
If different types of metals are interfaced in conductive structures, then functional requirements are met, but parasitic capacitance increases
Solution Approach 1:
The patent employs a single homogeneous conductive material for the entire conductive structure, eliminating metal-metal interfaces that generate parasitic capacitance. This uniform material approach maintains electrical functionality while minimizing capacitive effects that would arise from interfacing different metals with different dielectric properties.
4Length of moving object
If miniaturization is pursued to increase device density, then device size is reduced, but defect formation and performance reduction increase
Solution Approach 1:
The patent uses a homogeneous single-material conductive structure that eliminates interfaces where defects typically nucleate during miniaturization. This uniform material composition maintains structural integrity and electrical performance at smaller dimensions, preventing the defect formation and performance degradation associated with multi-material interfaces in miniaturized devices.
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 defect formation, surface roughness, and parasitic capacitance, while increasing gap-filling performance and reducing contact resistance, thereby enhancing the reliability and efficiency of semiconductor device conductive structures.
Implementation Method 1
a plasma-based deposition process that creates a silicon-rich surface
Implementation Method 2
a titanium precursor is used to selectively form a titanium silicide layer on source/drain regions
Implementation Method 3
silicon in the source/drain region to diffuse to a top surface of the source/drain region
Data Source
AI summary
A titanium precursor is used to selectively form a titanium silicide (TiSix) layer in a semiconductor device. A plasma-based deposition operation is performed in which the titanium precursor is provided into an opening, and a reactant gas and a plasma are used to cause silicon to diffuse to a top surface of a transistor structure. The diffusion of silicon results in the formation of a silicon-rich surface of the transistor structure, which increases the selectivity of the titanium silicide formation relative to other materials of the semiconductor device. The titanium precursor reacts with the silicon-rich surface to form the titanium silicide layer. The selective titanium silicide layer formation results in the formation of a titanium silicon nitride (TiSixNy) on the sidewalls in the opening, which enables a conductive structure such as a metal source/drain contact to be formed in the opening without the addition of another barrier layer.