Cobalt-Coated Copper Bond Pads for Oxidation Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper bond pads in semiconductor package devices oxidize over time, leading to unreliable wirebond connections, and the use of gold to prevent oxidation increases manufacturing costs.
Innovation Solution
A cobalt-containing layer is deposited over the copper bond pads to protect them from oxidation, improving the reliability of wirebond connections while maintaining cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cobalt-containing layer is deposited over the copper bond pad, then oxidation resistance is improved, but manufacturing complexity increases
Solution Approach 1:
A cobalt-containing layer is deposited over the copper bond pad to serve as an intermediary protective barrier. This layer prevents direct contact between oxygen and the copper surface, thereby preventing oxidation while maintaining electrical conductivity and wirebondability.
Solution Approach 2:
The bond pad structure is transformed from a single-material copper pad to a composite structure consisting of a copper base layer and a cobalt-containing protective layer. This composite structure combines the electrical conductivity of copper with the oxidation resistance of cobalt.
2Reliability
If gold is deposited over the copper pad to prevent oxidation, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive gold plating with a cheaper cobalt-containing layer that provides equivalent oxidation protection. This substitution significantly reduces manufacturing costs while maintaining the necessary reliability for wirebond connections.
Solution Approach 2:
The invention changes the material parameter from gold to cobalt-containing compounds, altering the cost characteristic while preserving the protective function. The cobalt layer can be applied through cost-effective deposition processes.
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 cobalt-containing layer effectively prevents copper pad oxidation, enhancing the reliability of wirebond connections and reducing manufacturing costs by providing a robust and oxidation-resistant finish.
Implementation Method 1
The cobalt-containing layer protects the copper bond pad from oxidation
Implementation Method 2
A cobalt-containing layer is deposited over the copper bond pads
Data Source
AI summary
The present disclosure provides embodiments of package devices and methods for making package devices for a semiconductor die. One embodiment includes a die mounting structure having a finished bond pad that includes a copper bond pad and a cobalt-containing layer over a top surface of the copper bond pad, and a wire bond structure that is bonded to a top surface of the cobalt-containing layer of the finished bond pad, where cobalt-containing material of the cobalt-containing layer is located between a bottom surface of the wire bond structure and the top surface of the copper bond pad such that the cobalt-containing material is present under a center portion of the wire bond structure.