Semiconductor Metal Layer Structure for Solder Spread Containment
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Solution Overview
Problem
Existing semiconductor devices face issues with solder wetting and spreading, leading to variability in device characteristics due to the high solder wettability of metal layers, which can result in unwanted contact with the semiconductor substrate's side surfaces.
Innovation Solution
A semiconductor device with a metal layer comprising a first metal layer of lower solder wettability exposed on the side surfaces and a second metal layer of higher solder wettability on the main surface, featuring a protruding portion along the outer peripheral edge to restrict solder spreading, and a manufacturing method involving a pressing member to form a groove and crack, creating a protruding portion during wafer division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal layer with high solder wettability is used, then solder wets and spreads well on the main surface, but solder may reach the side surface of the semiconductor substrate causing device characteristic variation
Solution Approach 1:
The patent applies local quality by creating different metal layer configurations at different locations: the main surface has a metal layer with high solder wettability for good soldering, while the side surface has a metal layer with low solder wettability to prevent unwanted solder spreading. This spatial differentiation of material properties resolves the contradiction between achieving good solder wettability and preventing solder from reaching the semiconductor substrate side surface.
2Ease of manufacture
If the metal layer is made with uniform composition, then manufacturing is simple, but solder spreads uncontrollably to the side surface
Solution Approach 1:
The patent implements local quality through a two-layer metal structure where the first metal layer (with low solder wettability) is deposited first as a base layer, followed by a second metal layer (with high solder wettability) on the main surface. This layered approach allows different regions of the metal layer to have different solder wettability characteristics, enabling precise control over solder spreading while maintaining manufacturability through standard deposition processes.
Solution Approach 2:
The patent uses composite materials by combining two different metal layers with distinct solder wettability properties. The first metal layer provides a low wettability barrier, while the second metal layer provides high wettability for the main surface. This composite structure enables simultaneous achievement of controlled solder spreading and good soldering performance.
3Reliability
If the metal layer is designed to prevent solder spreading, then device reliability improves, but solder wettability on the main surface may be insufficient
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial differentiation of metal layer properties. The side surface region uses a metal layer with low solder wettability to contain solder, while the main surface region uses a metal layer with high solder wettability to ensure proper soldering. This localized optimization allows the structure to simultaneously achieve both solder containment and adequate wettability where needed.
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
Effectively restricts unnecessary solder wetting and spreading while maintaining adequate solder 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 main surface of the metal layer is provided with the protruding portion that extends to make one round along the outer peripheral edge of the main surface. Therefore, when the metal layer is soldered to the target member, the solder is blocked by the protruding portion
Implementation Method 3
the first metal layer having a lower solder wettability is exposed on the side surface of the metal layer, the solder is less likely to wet and spread on the side surface of the metal layer
Data Source
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AI summary
A semiconductor device (10) includes a semiconductor substrate (12) and a metal layer (20) disposed on a surface (12a) of the semiconductor substrate. The metal layer includes a first metal layer (22, 24) and a second metal layer (26). 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 (20a) of the metal layer. The first metal layer is exposed on a side surface (20b) of the metal layer. The metal layer has a protruding portion (30) on the main surface. The protruding portion extends to make one round along an outer peripheral edge of the main surface.