MOSFET Drain Connector Structure for Uniform Bonding Gaps
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Solution Overview
Problem
Semiconductor devices with vertical MOSFETs face challenges in connecting semiconductor chips due to uneven film thickness of bonding materials, which leads to susceptibility to stress, warping, and thermal resistance issues, particularly when the chip has a protrusion and voids form during vacuum-reflow heat treatment.
Innovation Solution
The semiconductor device employs a drain connector with a thinner first plate portion and a thicker second plate portion, along with a slope on the upper surface of the connector, to equalize the gap between the chip and connectors, reducing void formation and thermal resistance by using a specific bonding material with controlled thickness and void diameter, and optimizing the angle of the slope for stable chip placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional connector with uniform plate thickness is used, then the manufacturing process is simple, but the bonding material film thickness becomes uneven, leading to stress susceptibility and warping
Solution Approach 1:
The connector plate is designed with non-uniform thickness, featuring a first plate portion with greater thickness and a second plate portion with lesser thickness. This local variation in quality compensates for the protrusion on the semiconductor chip, ensuring uniform bonding material film thickness across the bonding area despite the chip's uneven surface.
Solution Approach 2:
The connector structure intentionally introduces asymmetry through varying plate thickness in different regions. The first plate portion has greater thickness while the second plate portion has lesser thickness, creating an asymmetric profile that matches the asymmetric protrusion on the chip, thereby achieving uniform bonding film thickness.
2Stability of the object's composition
If the connector plate thickness is increased to reduce warping, then structural stability improves, but void formation increases during vacuum-reflow heat treatment
Solution Approach 1:
Different regions of the connector plate have different thicknesses: the first plate portion has greater thickness to provide structural stability and prevent warping, while the second plate portion has lesser thickness to reduce volume and minimize void formation during vacuum-reflow heat treatment. This local differentiation resolves the contradiction between stability and void reduction.
Solution Approach 2:
The connector plate is segmented into distinct portions with different thickness characteristics. The first plate portion and second plate portion are functionally separated, with each optimized for its specific role: one for structural stability and the other for minimizing void formation during thermal processing.
3Object-generated harmful factors
If the bonding material film thickness is reduced to minimize voids, then void formation decreases, but thermal resistance increases
Solution Approach 1:
The connector plate's non-uniform thickness distribution compensates for reduced bonding material thickness. The first plate portion with greater thickness provides enhanced thermal conduction capability to offset the increased thermal resistance from thinner bonding material, while the overall design minimizes void formation through optimized geometry.
Data Source
Figure 1
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Figure 3A~3B
AI summary
A semiconductor device includes: a first connector including a first plate having a first upper surface and a first terminal connected to the first plate, a first plate including a second plate and a third plate, a plate thickness of the second plate being thinner than a plate thickness of the third plate, the third plate being provided between the second plate and the first terminal; a semiconductor chip provided on the first upper surface; a first bonding material provided between the first upper surface and the semiconductor chip; a second connector provided on the semiconductor chip, a third connector, the first plate being provided between the first terminal and the third connector; a second bonding material provided between the second connector and the semiconductor chip; and a third bonding material provided between the second connector and the third connector.