Semiconductor Packaging With Diffusion Barrier on Columnar Electrode
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Solution Overview
Problem
Conventional semiconductor packaging structures face issues with solder balls easily falling off from copper pillars due to low mechanical strength and the formation of tin-copper intermetallic compounds during high-temperature reflow, leading to chip failure.
Innovation Solution
A semiconductor packaging structure is developed with a diffusion barrier layer on the sidewalls and top surface of a columnar electrode, preventing the formation of tin-copper intermetallic compounds and increasing the binding force between the solder ball and the columnar electrode, ensuring the solder ball wraps around the electrode for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a solder ball is formed directly on a copper pillar, then the packaging structure is simple, but the solder ball easily falls off due to low mechanical strength and formation of tin-copper intermetallic compounds
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the copper pillar and the solder ball. This barrier layer prevents direct contact between tin and copper, blocking the formation of tin-copper intermetallic compounds while maintaining the simplicity of the overall packaging structure.
Solution Approach 2:
The packaging structure uses a composite material approach by combining the copper pillar with a diffusion barrier layer made of different material properties. This composite structure provides both the electrical conductivity of copper and the protective properties of the barrier layer, preventing solder ball detachment.
2Reliability
If a diffusion barrier layer is added to prevent tin-copper intermetallic compound formation, then solder ball detachment is prevented, but the device complexity increases
Solution Approach 1:
The diffusion barrier layer serves as a thin intermediary film that adds minimal complexity while providing substantial protective function. By placing this barrier layer only where needed (on the copper pillar surface), the design achieves reliability improvement with minimal increase in overall device complexity.
Solution Approach 2:
The invention changes the material parameter of the interface between copper pillar and solder ball by introducing a diffusion barrier layer. This parameter change (from direct metal-to-metal contact to barrier-mediated contact) fundamentally alters the chemical interaction, preventing intermetallic compound formation while adding minimal structural complexity.
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 diffusion barrier layer effectively prevents solder ball detachment, improving the reliability and stability of the packaging structure by maintaining the solder ball's adherence to the columnar electrode even under external forces.
Implementation Method 1
A diffusion barrier layer can be formed on sidewalls and a top surface of the columnar electrode, and on the exposed portion of the metal interconnect structure surrounding the bottom of the columnar electrode
Data Source
AI summary
Various embodiments provide semiconductor packaging structures and methods for forming the same. In an exemplary method, a chip having a metal interconnect structure thereon can be provided. An insulating layer can be formed on the chip to expose the metal interconnect structure. A columnar electrode can be formed on the metal interconnect structure. A portion of the metal interconnect structure surrounding a bottom of the columnar electrode can be exposed. A diffusion barrier layer can be formed on sidewalls and a top surface of the columnar electrode, and on the exposed portion of the metal interconnect structure surrounding the bottom of the columnar electrode. A solder ball can then be formed on the diffusion barrier layer. The solder ball can wrap at least the sidewalls and the top surface of the columnar electrode.