Semiconductor Bump Diffusion Barrier Bi-Layer for 3D Stacking
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Solution Overview
Problem
Conventional semiconductor 3D stacking processes face reliability issues due to the thick Ni—P Under-Bump Metallization (UBM) layer and intense interaction between copper and solder materials, leading to volume increase and mechanical strength concerns.
Innovation Solution
A diffusion barrier bi-layer is introduced, comprising a nickel-phosphorus alloy layer and a copper layer, with specific thickness ranges, to suppress interaction between copper and solder, forming a Cu6Sn5 intermetallic compound that enhances the diffusion barrier effect and maintains a thin profile suitable for semiconductor 3D stacking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick Ni-P diffusion barrier layer (5-10 μm) is used, then the diffusion barrier effect is improved, but the volume of the bump increases and mechanical strength decreases
Solution Approach 1:
The patent divides the single thick diffusion barrier layer into a bi-layer structure consisting of a Ni-P alloy layer (first diffusion barrier layer, 0.8-1.6 μm) and a Cu layer (second diffusion barrier layer, 0.4-0.8 μm). This segmentation allows each layer to perform specific functions: the Ni-P layer provides primary diffusion barrier protection while the Cu layer suppresses intense interaction between Cu and solder material, achieving effective diffusion barrier with reduced total thickness (1.2-2.4 μm) and improved mechanical strength.
2Reliability
If a thick Ni-P diffusion barrier layer (5-10 μm) is used, then the diffusion barrier effect is improved, but the mechanical strength of the bump decreases
Solution Approach 1:
The patent divides the single thick diffusion barrier layer into a bi-layer structure consisting of a Ni-P alloy layer (first diffusion barrier layer, 0.8-1.6 μm) and a Cu layer (second diffusion barrier layer, 0.4-0.8 μm). This segmentation allows each layer to perform specific functions: the Ni-P layer provides primary diffusion barrier protection while the Cu layer suppresses intense interaction between Cu and solder material, achieving effective diffusion barrier with reduced total thickness (1.2-2.4 μm) and improved mechanical strength.
3Ease of manufacture
If copper is bonded directly with solder material, then the manufacturing process is simplified, but intense interaction between copper and solder material decreases reliability
Solution Approach 1:
The patent introduces a Cu layer as the second diffusion barrier layer between the conductive layer and the solder material. This intermediary Cu layer suppresses the intense interaction between Cu and solder material during bonding, preventing degradation of the Cu layer and improving bump reliability, while still allowing the bonding process to proceed effectively.
4Volume of moving object
If volume reduction is achieved in semiconductor 3D stacking, then the process suitability is improved, but the diffusion barrier effect may be compromised
Solution Approach 1:
The patent divides the diffusion barrier into a bi-layer structure with optimized thicknesses: Ni-P alloy layer (0.8-1.6 μm) and Cu layer (0.4-0.8 μm), achieving total thickness of 1.2-2.4 μm. This segmentation allows each layer to contribute to the diffusion barrier effect with thinner individual layers, maintaining effective diffusion protection while enabling volume reduction for semiconductor 3D stacking applications.
Solution Approach 2:
The patent uses a composite bi-layer structure combining Ni-P alloy and Cu materials. The Ni-P alloy provides baseline diffusion barrier properties while the Cu layer adds suppression of intense Cu-solder interaction. This composite structure achieves superior diffusion barrier performance with reduced total thickness compared to conventional single-layer approaches, making it suitable for volume-constrained 3D stacking.
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 bi-layer significantly improves the mechanical strength and reliability of semiconductor 3D stacking by preventing nickel diffusion and delaying the disintegration of the diffusion barrier layer, while maintaining a thin thickness suitable for the process.
Implementation Method 1
a first diffusion barrier layer formed on or above the conductive layer, and comprising an alloy of nickel and phosphorus
Implementation Method 2
forming a Cu6Sn5 intermetallic compound that enhances the diffusion barrier effect
Implementation Method 3
forming a conductive layer by depositing copper on or above an object in an electroplating method
Implementation Method 4
forming a first diffusion barrier layer by depositing an alloy of nickel and phosphorus on or above the conductive layer in an electroless-plating method
Data Source
AI summary
Provided herein is a bump including a diffusion barrier bi-layer, the bump having: a conductive layer; a first diffusion barrier layer formed on or above the conductive layer, and comprising an alloy of nickel and phosphorus; a second diffusion barrier formed on or above the first diffusion barrier layer, and comprising copper; and a solder layer formed on or above the second diffusion barrier layer. A manufacturing method for producing a bump is also provided.