Copper Wire Electromigration Resistance via Localized Metallic Segregation
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Solution Overview
Problem
As semiconductor devices miniaturize, the increased electric current density in copper wires leads to electromigration, compromising reliability, and adding more metallic elements to inhibit electromigration results in higher wiring resistance, creating a tradeoff between the two.
Innovation Solution
A metallic element with higher reducing power than copper is selectively segregated in specific regions of the copper wire, such as the center and upper side faces, using a two-step 'Cu reflow process and surface oxidation treatment to improve electromigration resistance without increasing wiring resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the quantity of added metallic element increases to inhibit electromigration, then electromigration resistance is improved, but wiring resistance increases
Solution Approach 1:
The patent applies local quality by selectively segregating metallic elements with higher reducing power than copper to specific regions within the copper wire: at the inner part apart from both the surface and bottom face, and at the side face part closer to the surface than the bottom face. This localized distribution provides electromigration resistance where needed while minimizing the overall quantity of added metallic elements, thus avoiding significant increase in wiring resistance.
Solution Approach 2:
The patent segments the copper wire into multiple regions with different metallic element concentrations. By dividing the wire structure and applying metallic elements to discrete regions rather than uniformly throughout, the invention achieves effective electromigration inhibition in critical areas while keeping the total amount of added elements low, resolving the tradeoff between reliability and energy loss.
2Productivity
If copper wire miniaturization advances to achieve downsizing and higher integration, then device integration is improved, but electric current density increases causing electromigration
Solution Approach 1:
The patent addresses the electromigration issue in miniaturized copper wires by applying local quality enhancement through selective metallic element segregation to specific high-stress regions. This allows the copper wire to maintain low overall resistance suitable for miniaturization while providing localized electromigration resistance in critical areas, enabling both downsizing and high integration without sacrificing reliability.
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 effectively enhances electromigration resistance at critical areas within the copper wire while maintaining low wiring resistance, thereby improving the overall reliability of the semiconductor device without increasing the quantity of added metallic elements.
Implementation Method 1
The electromigration of copper caused by electric current is inhibited and the reliability of a copper wire is improved by slightly adding another metallic element to the copper wire
Implementation Method 2
forming a first copper film containing a metallic element having a reducing power higher than copper over an insulating film including the inner wall of a wiring gutter by a sputtering method
Implementation Method 3
applying a first annealing treatment
Data Source
AI summary
The reliability of a copper wire is improved without inhibiting the wiring resistance of the copper wire. For example, another metallic element segregates in the boundary region between a copper film CUF1 and a copper film CUF2, and at the upper side face part of a wiring gutter leading to the boundary region. In a sectional view, a metallic element having a reducing power higher than copper segregates at the inner part of the copper wire apart from both the surface of the copper wire and the bottom face of the wiring gutter and at the side face part of the copper wire. In a sectional view, a metallic element different from copper segregates in the vicinity of the center part of the copper wire and at the side face part of the copper wire.