Dummy Patterns Adjacent to Metal Pads Prevent Passivation Cracking

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Solution Overview

Problem

The existing interconnect structures in integrated circuits, including connector structures with aluminum pads and copper pillars, face limitations in performance and density due to issues such as passivation cracking, which can lead to electrical failures and signal interference.

Innovation Solution

The introduction of dummy patterns adjacent to metal pads, formed of the same material and level as the pads, which create a partial or full ring surrounding the pads, helps to reduce stress and prevent passivation cracking, thereby enhancing the robustness of connector structures and minimizing electrical interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If connector structures with aluminum pads and copper pillars are used, then electrical connections are established, but passivation cracking occurs leading to electrical failures

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpassivation cracking

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The dummy pattern is formed adjacent to the metal pad before the passivation layer is applied, creating a stress-compensating structure in advance. This preliminary action prevents passivation cracking from occurring during subsequent processing or operation, thereby maintaining electrical connection reliability without the harmful effects of cracking.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dummy pattern acts as an intermediary structure between the metal pad and the passivation layer. It absorbs and redistributes stress that would otherwise be transmitted to the passivation layer, preventing cracking while maintaining the electrical connection function of the metal pad.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If dummy patterns are added adjacent to metal pads, then passivation cracking is reduced, but device structure becomes more complex

Engineering Contradiction:

Improvepassivation cracking reductionVSAvoidconnector structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The dummy pattern is placed only in specific locations adjacent to metal pads where stress concentration occurs, rather than uniformly across the entire device. This localized approach reduces passivation cracking at critical points while minimizing the increase in overall device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The dummy pattern uses the same material and dimensions as the metal pad, creating a simple geometric copy. This parameter matching simplifies the manufacturing process and reduces structural complexity compared to using different materials or complex geometries, while still effectively reducing passivation cracking.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8659123B2Metal pad structures in dies

Publication Date: 2014.02.25 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A die includes a substrate, a metal pad over the substrate, and a passivation layer that has a portion over the metal pad. A dummy pattern is disposed adjacent to the metal pad. The dummy pattern is level with, and is formed of a same material as, the metal pad. The dummy pattern forms at least a partial ring surrounding at least a third of the metal pad.