Basin-Shaped Underbump Pads for Small Solder Joint Reliability
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Solution Overview
Problem
As semiconductor devices scale down, the reduced size of solder material portions adversely impacts the reliability of solder joints due to a decrease in the adhesion area between the solder material portions and underbump structures.
Innovation Solution
The formation of basin-shaped underbump metallization pads with a recessed center and raised rim, which are formed on copper pads using a copper plating process, enhances the adhesion area and improves the reliability of solder joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of solder material portions is decreased to accommodate higher connection density, then the number of electrical connections per unit area increases, but the adhesion area between solder material portions and underbump structures decreases, adversely impacting solder joint reliability
Solution Approach 1:
The patent transitions from a planar underbump structure to a three-dimensional basin-shaped structure with a recessed center and raised rim. This dimensional change allows the underbump plate to provide increased adhesion area vertically and radially, compensating for the reduced solder material size while maintaining high connection density
Solution Approach 2:
The underbump plate features non-uniform thickness distribution with a recessed center portion and raised rim portion, creating different local geometries optimized for specific functions: the raised rim provides enhanced adhesion for small solder joints, while the recessed center accommodates the solder material portion
2Ease of manufacture
If conventional planar underbump structures are used, then the manufacturing process is simple, but the adhesion area is insufficient for small solder material portions, reducing solder joint reliability
Solution Approach 1:
The basin-shaped underbump structure is formed in advance through copper plating processes before solder application. The recessed center and raised rim geometry are pre-established to provide optimal adhesion surfaces, eliminating the need for complex post-processing or assembly adjustments
Solution Approach 2:
The patent modifies the geometric parameters of the underbump plate by creating a basin-shaped profile with specific depth and rim height. These parameter changes increase the effective adhesion area and provide mechanical interlocking features that enhance solder joint reliability without complicating the overall manufacturing process
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 basin-shaped underbump metallization pads increase the adhesion area, thereby improving the reliability and stability of solder joints in semiconductor devices.
Implementation Method 1
formed on copper pads using a copper plating process
Data Source
AI summary
A semiconductor structure includes a semiconductor die containing an array of first bonding structures. Each of the first bonding structures includes a first metal pad located within a dielectric material layer and a basin-shaped underbump metallization (UBM) pad located within a respective opening in a passivation dielectric layer and contacting the first metal pad. An interposer includes an array of second bonding structures, wherein each of the second bonding structures includes an underbump metallization (UBM) pillar having a respective cylindrical shape. The semiconductor die is bonded to the interposer through an array of solder material portions that are bonded to a respective one of the first-type bonding structures and to a respective one of the second-type bonding structures.