Dummy Via Layout for CMP Galvanic Corrosion in Interconnects

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Solution Overview

Problem

Galvanic corrosion during chemical mechanical polishing (CMP) leads to excessive removal of metal materials in conductive vias, resulting in poor interconnection quality in semiconductor devices.

Innovation Solution

Forming a dummy via with a width smaller than 50% of the conductive via on the terminal portion of a conductive structure, which reduces electron accumulation and minimizes galvanic corrosion by acting as an electron gatherer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive vias are formed on terminal portions of conductive structures, then interconnection quality is improved, but galvanic corrosion occurs during CMP causing excessive metal removal

Engineering Contradiction:

Improveinterconnection qualityVSAvoidmetal material removal

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

A dummy via is introduced as an intermediary element between the conductive via and the terminal portion of the conductive structure. This dummy via acts as a mediator that absorbs excess electrons during CMP, protecting the conductive via from galvanic corrosion while maintaining interconnection quality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of galvanic corrosion into a beneficial protective mechanism. By intentionally placing a dummy via that attracts electrons, the harmful electron accumulation that causes corrosion is redirected to the dummy via, thereby protecting the actual conductive via

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If dummy via width is reduced to less than 50% of conductive via width, then galvanic corrosion is minimized, but manufacturing precision requirements increase

Engineering Contradiction:

Improveprotection from galvanic corrosionVSAvoidvia width control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention specifies a quantitative parameter relationship where the dummy via width is controlled to be less than 50% of the conductive via width. This parameter change optimizes the protective function while providing a clear manufacturing target

Inventive Principle:

Principle #35Parameter 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

Reduces the risk of excessive metal removal and enhances interconnection quality by mitigating 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

Methodology Applied

Scientific EffectGalvanic corrosion:

Data Source

PatentUS12543548B2Semiconductor structure and method for forming the same

Publication Date: 2026.02.03 UNITED MICROELECTRONICS CORP

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 connecting 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, and a dummy via through the second dielectric layer and directly contacting the terminal portion. In a cross-sectional view, a width of the dummy via is smaller than 50% of a width of the conductive via.