Semiconductor Metal Layer Structure for Solder Spread Restriction
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Solution Overview
Problem
In semiconductor devices, solder wettability and spreading can lead to variations in device characteristics, as solder may reach the side surfaces of the semiconductor substrate, causing unwanted wetting and spreading.
Innovation Solution
A semiconductor device with a metal layer comprising a first metal layer and a second metal layer, where the second metal layer has higher solder wettability and is exposed on the main surface, and the first metal layer is exposed on the side surfaces, featuring a protruding portion along the outer peripheral edge to restrict solder spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer with high solder wettability is used, then soldering performance is improved, but solder spreads to side surfaces causing unwanted wetting
Solution Approach 1:
The patent applies local quality by creating different metal layer configurations at different locations: the main surface has a metal layer structure optimized for solder wettability, while the side surfaces have a different structure that restricts solder spreading. This is achieved through selective exposure of different metal layers (first metal layer on side surfaces, second metal layer on main surface) and the protruding portion geometry, allowing each region to have properties suited to its function.
2Object-affected harmful factors
If the metal layer is made to restrict solder spreading, then solder containment is improved, but solder wettability on the main surface may be reduced
Solution Approach 1:
The patent segments the metal layer into multiple distinct layers: a first metal layer and a second metal layer with different properties. The second metal layer with higher solder wettability is exposed on the main surface to ensure good soldering, while the first metal layer is exposed on the side surfaces to restrict solder spreading. This segmentation allows each layer to fulfill its specific function without compromising the other.
3Object-affected harmful factors
If a protruding portion is added to the metal layer, then solder spreading is restricted, but device complexity increases
Solution Approach 1:
The patent utilizes the vertical dimension by creating a protruding portion that extends upward from the main surface of the metal layer. This three-dimensional structure effectively blocks solder from spreading to the side surfaces of the semiconductor substrate. The protruding portion acts as a physical barrier in the vertical dimension, preventing lateral solder flow without requiring additional separate components.
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 solution effectively restricts unnecessary solder wetting and spreading while maintaining suitable wettability on the main surface, preventing solder from reaching the semiconductor substrate's side surfaces.
Implementation Method 1
The second metal layer covers a surface of the first metal layer and has a higher solder wettability than the first metal layer
Implementation Method 2
The metal layer has a protruding portion on the main surface. The protruding portion extends to make one round along an outer peripheral edge of the main surface
Data Source
AI summary
A semiconductor device includes a semiconductor substrate and a metal layer disposed on a surface of the semiconductor substrate. The metal layer includes a first metal layer and a second metal layer. The second metal layer covers a surface of the first metal layer and has a higher solder wettability than the first metal layer. The second metal layer is exposed on a main surface of the metal layer. The first metal layer is exposed on a side surface of the metal layer. The metal layer has a protruding portion on the main surface. The protruding portion extends to make one round along an outer peripheral edge of the main surface.