MOSFET Bonding Surface Layout to Limit Solder Wet Spreading
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Solution Overview
Problem
Semiconductor devices with MOSFETs using compound semiconductor substrates face displacement issues due to the lightweight nature of the MOSFETs and the wet spreading of solder bonding layers during reflow soldering, leading to unregulated wetting and spreading over the support member.
Innovation Solution
A semiconductor device design featuring a support member with a metal layer having a first region in contact with the bonding layer and a second region adjacent to it, where the second region is more repellent to the liquid phase of the metal composition, and a manufacturing method involving laser irradiation of the second region to control the wetting and spreading of the bonding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the MOSFET is bonded to the support member via a bonding layer using conventional reflow soldering, then the bonding process is simple and efficient, but the MOSFET may be displaced relative to the support member due to wet spreading of the bonding layer
Solution Approach 1:
The support member is designed with a metal layer that has different surface properties in different regions: a first region with standard wettability for bonding, and a second region with reduced wettability (more repellent to liquid phase metal composition) to prevent excessive spreading. This local differentiation of surface properties allows the bonding layer to be confined to the intended area, preventing MOSFET displacement while maintaining efficient bonding in the first region.
2Area of stationary object
If the bonding layer is allowed to spread freely over the support member, then the bonding coverage is increased, but the MOSFET displacement is caused
Solution Approach 1:
The metal layer on the support member is designed with spatially varying wettability: the first region provides adequate bonding coverage, while the second region with reduced wettability acts as a barrier to prevent further spreading. This ensures the bonding layer covers the necessary area for reliable bonding without extending beyond the intended boundary, thus preventing MOSFET displacement.
Solution Approach 2:
The metal layer is pre-formed with distinct first and second regions having different wettability properties before the bonding process. This preliminary structuring of the support member surface ensures that when the bonding layer is applied, its spreading is automatically limited by the pre-defined boundary of the second region, preventing displacement without requiring additional control mechanisms during bonding.
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 regulates the wetting and spreading of the bonding layer, preventing MOSFET displacement and improving manufacturing efficiency by ensuring precise bonding and heat dissipation in semiconductor devices.
Implementation Method 1
a step of irradiating a second region of the metal layer with a laser between the step of forming the metal layer and the step of arranging the semiconductor element
Implementation Method 2
bonding the semiconductor element to the metal layer by melting and solidifying the bonding material
Data Source
AI summary
A semiconductor device includes: a support member having an obverse surface facing in a thickness direction; a semiconductor element mounted on the obverse surface; and a bonding layer that bonds the obverse surface and the semiconductor element. The support member has a base member, and a metal layer mounted on the base member and including the obverse surface. The support member includes a first region in contact with the bonding layer, and a second region adjacent to the first region as viewed in the thickness direction. The bonding layer contains a metal composition in a solid phase. The second region is more repellent to a liquid phase of the metal composition than the first region.