Ti-Ta Interconnection Barrier Stack for Low-Resistance Contacts
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving low resistance and cost-effective barrier metals for interconnections and via contacts to reduce wiring and contact resistance while preventing diffusion of wiring materials.
Innovation Solution
Utilizing a laminated structure of hexagonal titanium and body-centered cubic tantalum layers as barrier films in semiconductor devices, where titanium is used as the underlayer to facilitate the deposition of alpha-tantalum with lower specific resistance, thereby reducing the overall specific resistance of the barrier films and maintaining low manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier metal is provided to prevent diffusion of wiring material, then reliability is improved, but resistance increases
Solution Approach 1:
The barrier metal is divided into two separate layers: a first barrier metal layer (titanium) in contact with the wiring material and a second barrier metal layer (tantalum) on top of the first layer. This segmentation allows each layer to perform its function optimally - titanium provides diffusion barrier properties while tantalum provides low resistance, resolving the contradiction between diffusion prevention and resistance reduction
Solution Approach 2:
The invention uses a composite structure of two different metals (titanium and tantalum) stacked together. Titanium offers excellent diffusion barrier properties but higher resistance, while tantalum offers low resistance but weaker diffusion barrier properties. By combining these two materials in a layered composite structure, the system achieves both diffusion prevention and low resistance simultaneously
2Manufacturing precision
If expensive materials are used for barrier metal to achieve low resistance, then resistance is reduced, but manufacturing cost increases
Solution Approach 1:
Different regions of the barrier metal structure have different material properties optimized for their specific functions. The first barrier metal layer (titanium) has properties optimized for diffusion barrier performance where it contacts the wiring material, while the second barrier metal layer (tantalum) has properties optimized for low resistance where it contacts the upper interconnection. This local optimization allows cost-effective material selection for each region
Solution Approach 2:
The invention changes the material composition parameter of the barrier metal from a single material to a two-layer composite structure. By adjusting the thickness and material composition of each layer, the system achieves optimal balance between resistance and cost - using thinner layers of expensive tantalum and thicker layers of cheaper titanium, thereby reducing overall manufacturing cost while maintaining low resistance
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 laminated structure of titanium and alpha-tantalum barrier films effectively reduces contact and wire resistance while preventing diffusion of wiring materials, achieving a balance between cost-effectiveness and electrical performance.
Implementation Method 1
titanium is used as the underlayer to facilitate the deposition of alpha-tantalum with lower specific resistance
Data Source
AI summary
A semiconductor device according to the present embodiment comprises a first conductive layer. An interconnection is provided above the first conductive layer. A contact is provided between the first conductive layer and the interconnection. The interconnection includes a first metal layer containing hexagonal titanium (Ti) provided above the first conductive layer, a second metal layer containing tantalum (Ta) having a body-centered cubic lattice-like structure and provided on the first metal layer, and a first wiring material provided on the second metal layer.