Metal Bump Joint Structure for Semiconductor Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in achieving smaller form factors, cost-effectiveness, increased performance, and reduced heat generation in semiconductor devices due to limitations in packaging techniques, particularly in integrating higher density components without compromising reliability.
Innovation Solution
A metal bump joint structure is employed, where copper bumps with nickel or gold barrier layers are used, forming an intermetallic compound layer between semiconductor components, along with a solder joint structure that adheres to specific dimensional ratios to prevent crack propagation and enhance reliability through flip-chip bonding and reflow processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If chip-scale packaging is used to reduce physical size, then integration density and form factor are improved, but reliability and crack resistance deteriorate
Solution Approach 1:
The patent employs a composite joint structure consisting of a metal bump (first material) and a solder joint (second material) with different mechanical properties. The metal bump provides structural support and crack resistance, while the solder joint provides electrical connection and flexibility. This composite approach allows the device to maintain small form factor while improving reliability through the synergistic combination of materials with complementary properties.
Solution Approach 2:
The patent applies different material properties to different parts of the joint structure. The metal bump region is designed with higher strength and stiffness to prevent crack propagation, while the solder joint region is designed with appropriate ductility to accommodate thermal expansion differences. This local differentiation of material qualities optimizes both size reduction and reliability.
2Productivity
If integration density is increased through smaller features, then productivity and performance are improved, but manufacturing complexity and heat generation worsen
Solution Approach 1:
The joint structure is segmented into distinct functional regions: a metal bump portion for mechanical strength and a solder joint portion for electrical connection and thermal management. This segmentation allows each region to be optimized independently for its specific function, simplifying the manufacturing process by enabling separate formation steps while achieving high integration density.
3Reliability
If metal bumps with barrier layers are used to prevent diffusion, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The diffusion barrier layer is formed on the metal bump before the solder joint is applied. This preliminary action prevents intermetallic diffusion during the bonding and reflow processes, ensuring long-term reliability. The barrier layer is integrated into the existing metal bump formation process, minimizing additional manufacturing steps while providing essential diffusion protection.
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
This approach results in improved reliability and thermal cycle performance of stacked semiconductor chips by preventing crack propagation and ensuring a robust solder joint structure, leading to enhanced integration density, smaller form factors, and cost-effectiveness.
Implementation Method 1
an intermetallic compound layer at an interface between the first metal bump and the second metal bump
Data Source
AI summary
A structure comprises a first semiconductor chip with a first metal bump and a second semiconductor chip with a second metal bump. The structure further comprises a solder joint structure electrically connecting the first semiconductor chip and the second semiconductor chip, wherein the solder joint structure comprises an intermetallic compound region between the first metal bump and the second metal bump, wherein the intermetallic compound region is with a first height dimension and a surrounding portion formed along exterior walls of the first metal bump and the second metal bump, wherein the surrounding portion is with a second height dimension, and wherein the second height dimension is greater than the first height dimension.