Conductive Metal Capping Layer for IC Bond Pad Corrosion Protection
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Solution Overview
Problem
Integrated circuits (ICs) face reliability issues due to corrosion of bond pads and interconnect lines, especially in environments with high levels of air pollutants, which can lead to electrical opens and shorts, and existing protection methods are inadequate, particularly for exposed bond pad areas.
Innovation Solution
A metal capping layer is applied over the bond pad areas of ICs, using corrosion-resistant materials like aluminum or gold to protect the bond pad metals and extend to cover most of the IC die for additional shielding and thermal conductivity, eliminating the need for packaging materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bond pads are exposed to allow electrical contact, then electrical connectivity is enabled, but corrosion susceptibility increases
Solution Approach 1:
The patent segments the bond pad structure into multiple functional layers: the underlying bond pad metal for electrical connectivity and an overlying metal capping layer for corrosion protection. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between electrical accessibility and corrosion resistance.
Solution Approach 2:
The metal capping layer acts as an intermediary between the bond pad metal and the corrosive environment. It provides a protective barrier that prevents direct contact between corrosive agents and the bond pad metal, while still allowing electrical contact to occur through or alongside the capping layer structure.
2Object-affected harmful factors
If conventional packaging materials are used to protect ICs, then environmental protection is provided, but device complexity and cost increase
Solution Approach 1:
The patent merges the corrosion protection function directly into the IC die structure by integrating the metal capping layer as part of the bond pad assembly. This eliminates the need for separate packaging materials to provide corrosion protection, thereby reducing device complexity while maintaining protective functionality.
Solution Approach 2:
The metal capping layer serves multiple functions simultaneously: it provides corrosion protection for the bond pads, acts as an electromagnetic shield, and can serve as a thermal management layer. This multi-functionality replaces what would traditionally require multiple separate packaging components.
3Object-affected harmful factors
If metal capping layer covers most of IC die area, then electromagnetic shielding is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes changes in deposition parameters and material properties to enable effective electromagnetic shielding. By selecting appropriate metal materials and optimizing layer thickness, the capping layer achieves superior electromagnetic shielding characteristics that enhance manufacturability compared to more complex shielding structures.
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 metal capping layer effectively prevents corrosion and electrical interference, provides light shielding, and acts as a Faraday shield, enhancing the reliability and performance of ICs in harsh environments without the need for conventional packaging.
Implementation Method 1
The metal capping layer 120 can also be used to cover other areas of the IC die for providing light protection to the circuitry to avoid device failure or shifts due to p-n junction currents resulting from light exposure
Implementation Method 2
A metal capping layer is applied over the bond pad areas of ICs, using corrosion-resistant materials like aluminum or gold to protect the bond pad metals and extend to cover most of the IC die for additional shielding and thermal conductivity
Implementation Method 3
Disclosed metal capping layers when provided over most of the total IC die area can also provide an effective Faraday shield to provide electromagnetic and radiation shielding for the IC die
Data Source
AI summary
An integrated circuit (IC) die has a top side surface providing circuitry including active circuitry configured to provide a function, including at least one bond pad formed from a bond pad metal coupled to a node in the circuitry. A dielectric passivation layer is over a top side surface of a substrate providing a contact area which exposes the bond pad. A metal capping layer includes an electrically conductive metal or an electrically conductive metal compound over at least the contact area to provide corrosion protection to the bond pad metal, which is in electrical contact with the bond pad metal. The metal capping layer can extend over structures other than the bond pads, such as to cover at least 80% of the area of the IC die to provide structures on the IC die protection from incident radiation.