Copper Pillar Intermetallic Coating Prevents Migration
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Solution Overview
Problem
Copper structures in integrated circuit chips face issues with copper migration between adjacent structures during packaging, which can lead to electrical connectivity problems and reliability concerns.
Innovation Solution
A copper structure with a tin-copper intermetallic coating is applied to prevent copper migration, comprising a redistribution layer, a copper pillar, and a solder bump, where the intermetallic coating is formed through a reflow process involving a tin coating and a solder layer, effectively preventing copper ion migration and ensuring stable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper structures are used in integrated circuit chips, then electrical conductivity is improved, but copper migration between adjacent structures occurs during packaging
Solution Approach 1:
A barrier layer is introduced between adjacent copper structures to prevent copper migration. The barrier layer acts as an intermediary that blocks the movement of copper ions while allowing the copper structures to maintain their electrical function, thus resolving the contradiction between conductivity and migration prevention.
Solution Approach 2:
The copper structure is combined with a barrier layer to form a composite structure. This composite material approach allows the copper to provide electrical conductivity while the barrier layer prevents copper migration, achieving both improved conductivity and enhanced reliability simultaneously.
2Reliability
If barrier layers are added to prevent copper migration, then reliability is improved, but device complexity increases
Solution Approach 1:
The barrier layer is applied selectively only where copper migration is a concern, such as at interfaces between copper structures and other materials. This localized application prevents copper migration in critical areas while minimizing the overall addition of structural complexity.
Solution Approach 2:
The barrier layer formation process is merged with existing manufacturing steps, such as combining it with the copper deposition or packaging processes. This integration reduces the number of separate process steps and minimizes the increase in device complexity while still achieving copper migration prevention.
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 intermetallic coating effectively prevents copper migration, enhancing the reliability and stability of electrical connections between copper structures, thereby improving the packaging process and ensuring consistent performance of integrated circuit chips.
Implementation Method 1
A copper structure with a tin-copper intermetallic coating is applied to prevent copper migration, comprising a redistribution layer, a copper pillar, and a solder bump, where the intermetallic coating is formed through a reflow process involving a tin coating and a solder layer
Data Source
AI summary
An integrated circuit (IC) chip includes a copper structure with an intermetallic coating on the surface. The IC chip includes a substrate with an integrated circuit. A metal pad electrically connects to the integrated circuit. The copper structure electrically connects to the metal pad. A solder bump is disposed on the copper structure. The surface of the copper structure has a coating of intermetallic. The copper structure can be a redistribution layer and a copper pillar that is disposed on the redistribution layer.