Conductive Via Layout With Dummy Vias for CMP Galvanic Corrosion
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Solution Overview
Problem
Galvanic corrosion during chemical mechanical polishing (CMP) process leads to excessive removal of metal materials in conductive vias, resulting in poor interconnection quality in semiconductor devices.
Innovation Solution
Incorporation of dummy vias with a width smaller than 50% of the conductive vias on the terminal portion of the conductive structure, formed using different materials for the first and second filling layers, to reduce electron accumulation and minimize galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMP process is used for forming conductive vias, then manufacturing process is simple, but galvanic corrosion occurs causing excessive metal removal and poor interconnection quality
Solution Approach 1:
A dummy via structure is introduced as an intermediary element between the polishing slurry and the conductive via. The dummy via includes a lower portion filled with a first material and an upper portion filled with a second material, creating a gradient structure that mediates the galvanic interaction. This intermediary structure redistributes the galvanic corrosion effect, protecting the actual conductive via from excessive metal removal while maintaining overall process feasibility.
Solution Approach 2:
The dummy via employs composite material construction with at least two different materials in its lower and upper portions. This composite structure creates a controlled galvanic couple that protects the conductive via. The first material in the lower portion and the second material in the upper portion are selected to have different electrochemical potentials, forming a protective gradient that prevents direct galvanic attack on the conductive via metal.
2Reliability
If dummy via with small width is formed on terminal portion, then galvanic corrosion is reduced, but manufacturing precision requirement increases
Solution Approach 1:
The dummy via structure implements local quality by having different materials in its lower and upper portions, each serving specific functions. The lower portion uses a first material optimized for galvanic protection at the interface with the conductive via, while the upper portion uses a second material optimized for integration with the surrounding dielectric. This localized material differentiation achieves effective corrosion protection while maintaining manufacturability through standard multi-layer deposition techniques.
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
Reduces the risk of excessive metal removal and enhances interconnection quality by minimizing galvanic corrosion, ensuring stable metal surfaces and improved electrical connections.
Implementation Method 1
when the metal materials exposed to the polishing slurry have different electrical potentials, galvanic corrosion may occur between the metal materials
Data Source
AI summary
A semiconductor structure includes a first dielectric layer on a substrate, a conductive structure disposed in the first dielectric layer and including a terminal portion and an extending portion directly and physically connected to the terminal portion and extending away from the terminal portion, a second dielectric layer disposed on the first dielectric layer, a conductive via through the second dielectric layer and directly contacting the extending portion, a dummy via through the second dielectric layer and directly contacting the terminal portion, wherein the dummy via comprises a lower portion consisting of a first filling layer and an upper portion consisting of a second filling layer, wherein the first filling layer and the second filling layer comprise different materials.