IC Contact Structure Layout for High-Aspect-Ratio Reliability
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Solution Overview
Problem
The downscaling of integrated circuit (IC) devices has led to increased aspect ratios of contact structures, necessitating improvements in electrical properties and reliability.
Innovation Solution
The IC device incorporates a structure with first and second contact structures, where the second contact structure has a convex top surface and a higher vertical length than the first, utilizing tungsten liners and plugs with a nucleation layer to enhance electrical conductivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If contact structures are downscaled to reduce device size, then device integration density is improved, but aspect ratio of contact structures increases and electrical properties deteriorate
Solution Approach 1:
The patent applies different materials with specific properties to different regions of the contact structure. A first material (e.g., tungsten) is used for the lower contact structure portion to provide mechanical strength and low resistivity, while a second material (e.g., cobalt or copper) is used for the upper portion to provide low resistivity and good electromigration resistance. This local differentiation of material properties allows the contact structure to maintain electrical performance despite downscaled dimensions and increased aspect ratio.
Solution Approach 2:
The patent employs a composite contact structure consisting of multiple materials with complementary properties. The combination of a body-centered cubic structure material (tungsten) and a face-centered cubic structure material (cobalt or copper) creates a composite system where each material contributes its strengths: tungsten provides structural integrity and low resistivity, while cobalt/copper provides low resistivity and resistance to electromigration. This composite approach resolves the contradiction between miniaturization and electrical performance maintenance.
2Area of moving object
If contact structure planar size is reduced for downscaling, then device density is improved, but contact structure resistance increases
Solution Approach 1:
The patent addresses the resistance increase by applying different materials to different regions of the contact structure. The upper portion, which experiences higher current density and is more susceptible to resistance effects, is filled with a low-resistivity material (cobalt or copper). This local optimization of material properties compensates for the increased resistance that would result from reduced planar size.
Solution Approach 2:
The patent changes the material parameter (resistivity) of the contact structure by using different materials for different portions. The body-centered cubic material (tungsten) has resistivity of approximately 5.6 μΩ·cm, while the face-centered cubic material (cobalt or copper) has lower resistivity of approximately 6.2 μΩ·cm and 1.7 μΩ·cm respectively. This parameter change in material selection allows the contact structure to maintain low resistance despite reduced dimensions.
3Area of moving object
If conventional contact structure designs are used with increased aspect ratio, then device downscaling is achieved, but electrical reliability and performance are insufficient
Solution Approach 1:
The patent applies different materials with specific properties to different regions of the contact structure. A first material (e.g., tungsten) is used for the lower contact structure portion to provide mechanical strength and low resistivity, while a second material (e.g., cobalt or copper) is used for the upper portion to provide low resistivity and good electromigration resistance. This local differentiation of material properties allows the contact structure to maintain electrical performance despite downscaled dimensions and increased aspect ratio.
Solution Approach 2:
The patent employs a composite contact structure consisting of multiple materials with complementary properties. The combination of a body-centered cubic structure material (tungsten) and a face-centered cubic structure material (cobalt or copper) creates a composite system where each material contributes its strengths: tungsten provides structural integrity and low resistivity, while cobalt/copper provides low resistivity and resistance to electromigration. This composite approach resolves the contradiction between miniaturization and electrical performance maintenance.
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 design improves electrical properties and reliability by reducing resistance and maintaining structural integrity despite high aspect ratios, with the convex second contact structure providing superior conductivity and gap-fill characteristics.
Implementation Method 1
nonmetal or semimetal elements may be irregularly dispersed in the tungsten nucleation layer... This configuration improves the electrical resistance and reliability of contact structures, reducing resistance by up to 60%
Data Source
AI summary
An integrated circuit device includes a middle insulating structure on a substrate, a first contact structure passing through the middle insulating structure and extending by a first vertical length from a top surface of the middle insulating structure toward the substrate, and a second contact structure passing through the middle insulating structure. The middle insulating structure may have a top surface extending in a lateral direction at a first vertical level. The second contact structure may extend by a second vertical length greater than the first vertical length from the top surface of the middle insulating structure toward the substrate. The first contact structure may have a first top surface extending planar along an extension line of the top surface of the middle insulating structure. The second contact structure may have a second top surface, which may be convex in a direction away from the substrate.