Tin-Indium Protective Coating for Semiconductor Interconnect Oxidation
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Solution Overview
Problem
Semiconductor devices face issues with surface oxidation and corrosion of conductive pillars, which affect bonding reliability and increase manufacturing costs due to reduced yield.
Innovation Solution
A protective coating is formed over the interconnect structures and bump materials using tin (Sn) or indium (In) to inhibit oxidation and corrosion, specifically for Cu conductive pillars, enhancing bonding reliability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coating is formed over conductive pillars to inhibit surface oxidation, then bonding reliability is improved, but device complexity increases
Solution Approach 1:
A protective coating layer comprising tin (Sn) and/or indium (In) is deposited over the conductive pillars to act as an intermediary barrier between the copper material and the oxidizing environment. This coating prevents direct oxidation of the copper while maintaining electrical and mechanical functionality for bonding applications.
Solution Approach 2:
The protective coating utilizes composite material composition by combining tin and indium in specific ratios (Sn:In from 95:5 to 50:50 atomic percent) to create a material that provides both oxidation protection and suitable bonding characteristics, leveraging the complementary properties of both elements.
2Reliability
If a protective coating is formed over the interconnect structure, then corrosion resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The coating thickness is precisely controlled within a specific range of 0.5 to 5.0 micrometers, and the compositional ratio of Sn to In is optimized to achieve the desired balance between corrosion protection and manufacturing feasibility. These parameter optimizations enable effective protection while maintaining compatibility with existing manufacturing capabilities.
3Productivity
If a thin protective coating is used to maintain interconnect density, then productivity is maintained, but protection effectiveness may be reduced
Solution Approach 1:
The optimal coating thickness range of 0.5 to 5.0 micrometers was determined through parameter optimization, providing sufficient protection while maintaining interconnect density. The compositional ratio of Sn to In (95:5 to 50:50 atomic percent) is also optimized to maximize protection effectiveness within the constrained thickness.
Solution Approach 2:
By using a composite coating of tin and indium, the protection effectiveness is enhanced within the thin film constraint. The combination of elements provides superior corrosion and oxidation resistance compared to single-element coatings of the same thickness, ensuring adequate protection while maintaining productivity.
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 protective coating effectively reduces surface oxidation and corrosion, improving bonding reliability and manufacturing yield while maintaining a thin layer that does not interfere with interconnect density.
Implementation Method 1
A protective coating is formed over the interconnect structure and bump material to inhibit surface oxidation and corrosion
Data Source
AI summary
A semiconductor device has a semiconductor die with a first conductive layer formed over the semiconductor die. A first insulating layer is formed over the semiconductor die with a first opening in the first insulating layer disposed over the first conductive layer. A second conductive layer is formed over the first insulating layer and into the first opening over the first conductive layer. An interconnect structure is formed over the first and second conductive layers within openings of a second insulating layer. The second insulating layer is removed. The interconnect structure can be a conductive pillar or conductive pad. A bump material can be formed over the conductive pillar. A protective coating is formed over the conductive pillar or pad to a thickness less than one micrometer to reduce oxidation. The protective coating is formed by immersing the conductive pillar or pad into the bath containing tin or indium.