Copper Interconnect Passivation for Oxidation-Resistant Contacts
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Solution Overview
Problem
Existing interconnection structures for integrated circuits, particularly those with copper metallizations, face challenges in protecting copper elements from oxidation and corrosion, especially at the end of the interconnection structure most distant from the substrate, which is critical for maintaining electrical conductivity and preventing damage during encapsulation and contact formation.
Innovation Solution
A method involving the formation of a protection layer and a multilayer passivation structure, including silicon nitride and silicon dioxide layers, is implemented to protect copper interconnection elements. This method includes forming a first opening to maintain a residual passivation layer and an additional insulating layer with a second opening that exposes the protection layer, ensuring the copper remains protected while allowing access for contact and encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnection elements are used in the interconnection structure, then electrical conductivity and energy efficiency are improved, but susceptibility to oxidation and corrosion increases
Solution Approach 1:
A protection layer made of aluminum or hafnium is deposited over the copper interconnection elements to serve as an intermediary barrier between the copper and the oxidizing/corrosive environment. This protection layer prevents direct contact between copper and harmful atmospheric factors while maintaining the electrical conductivity benefits of copper interconnections.
Solution Approach 2:
The interconnection structure employs a composite material system consisting of copper interconnection elements combined with a protection layer of aluminum or hafnium. This composite structure integrates the high electrical conductivity of copper with the oxidation and corrosion resistance of aluminum or hafnium, creating a material system that exhibits both improved conductivity and enhanced environmental stability.
2Ease of operation
If the end of the interconnection structure is exposed for contact formation and encapsulation, then ease of operation is improved, but exposure to oxidizing and corrosive atmosphere increases
Solution Approach 1:
The protection layer is deposited over the copper interconnection elements before any contact formation or encapsulation processes. This preliminary protective action ensures that the copper surface is already protected when subsequent processing steps require exposure, allowing ease of operation while preventing oxidation and corrosion during manufacturing operations.
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 solution effectively protects copper interconnection elements from oxidation and corrosion, maintaining their integrity and enabling reliable contact formation and encapsulation, thereby enhancing the reliability and longevity of integrated circuit connections.
Implementation Method 1
protect the copper from air, or from any oxidizing and/or corrosive atmosphere
Data Source
AI summary
The present description relates to a method of manufacturing an end of an interconnection structure of an integrated circuit, the method including: providing an integrated circuit including an interconnection structure including copper interconnection elements at least partly extending through an insulating layer and flush with a first surface of said interconnection structure; forming a protection layer on the first surface of the interconnection structure, said protection layer including a material adapted to protecting the copper of the interconnection elements; forming a passivation layer on the protection layer, the passivation layer having a first thickness; and forming a first opening in the passivation layer across a second thickness smaller than the first thickness, to keep a residual passivation layer at the bottom of the first opening.