Selective Diffusion Barrier for IC Interconnects
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Solution Overview
Problem
In integrated circuit devices, the diffusion of different metals at backend processing temperatures can lead to voids, electrical defects, and device failure due to metal solubility and migration into dielectric materials, causing electrical leakage and shorts.
Innovation Solution
A selective diffusion barrier is implemented between metals, using a thin layer of materials like titanium nitride or tantalum nitride deposited by atomic layer deposition or chemical vapor deposition, which prevents diffusion between copper and other metals, reducing voids and electrical defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different metals are used in interconnect structures to increase electrical performance, then electrical performance is improved, but metal diffusion occurs at processing temperatures causing voids and electrical defects
Solution Approach 1:
A diffusion barrier layer comprising titanium nitride (TiN) and/or tantalum nitride (TaN) is introduced as an intermediary between different metal interconnects. This barrier layer prevents direct contact and diffusion between metals such as copper and cobalt at backend processing temperatures (up to 400°C), eliminating void formation and electrical defects while maintaining electrical performance.
Solution Approach 2:
The diffusion barrier employs composite material structures including alternating layers of titanium nitride and tantalum nitride (TiN/TaN), or titanium nitride with an underlying titanium layer (TiN/Ti). These composite structures provide enhanced diffusion prevention capabilities at processing temperatures while maintaining compatibility with copper and other metal interconnects.
2Ease of manufacture
If metals are allowed to diffuse during processing, then metallization can be simplified, but voids form in the metals causing electrical open circuits
Solution Approach 1:
The diffusion barrier layer is deposited on the metal interconnect surface before subsequent processing steps. This preliminary protective action prevents metal diffusion and void formation during backend processing, ensuring electrical continuity is maintained throughout manufacturing without requiring complex metallization adjustments.
3Stability of the object's composition
If metals diffuse into dielectric material, then metal redistribution occurs, but electrical leakage and dielectric breakdown result
Solution Approach 1:
The titanium nitride and/or tantalum nitride diffusion barrier serves as a mediator between metal interconnects and dielectric materials. It completely prevents metal atoms from diffusing into the dielectric, maintaining stable metal distribution while eliminating electrical leakage and dielectric breakdown that would result from metal contamination.
4Reliability
If a diffusion barrier is added between metals, then metal intermixing is prevented, but device complexity increases
Solution Approach 1:
The diffusion barrier is implemented as an ultra-thin film with nominal thickness of 1-10 nanometers. This thin film structure provides effective metal separation and diffusion prevention while adding minimal structural complexity to the interconnect system. The barrier can be deposited conformally on existing metal surfaces without requiring significant process or design changes.
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 selective diffusion barrier effectively reduces metal intermixing, void formation, and electrical leakage, enhancing the reliability and performance of integrated circuit interconnects by limiting metal diffusion into dielectric materials and preventing shorts.
Implementation Method 1
a third metal of a diffusion barrier is selectively deposited on the first metal without directly depositing on sidewalls of the opening
Implementation Method 2
deposited by atomic layer deposition or chemical vapor deposition
Implementation Method 3
deposited by atomic layer deposition or chemical vapor deposition
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5a
AI summary
Embodiments of the present disclosure describe a selective diffusion barrier between metals of an integrated circuit (IC) device and associated techniques and configurations. In one embodiment, an apparatus includes a dielectric material, a first interconnect structure comprising a first metal disposed in the dielectric material, a second interconnect structure comprising a second metal disposed in the dielectric material and electrically coupled with the first interconnect structure and a diffusion barrier disposed at an interface between the first interconnect structure and the second interconnect structure, wherein the first metal and the second metal have a different chemical composition, material of the diffusion barrier and the second metal have a different chemical composition and material of the diffusion barrier is not disposed directly between the second metal and the dielectric material. Other embodiments may be described and/or claimed.