Semiconductor Electrode Design for Warping Resistance
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Solution Overview
Problem
Semiconductor devices with flip-chip bonding experience warping due to thermal stress during manufacturing, leading to reduced contact area and deteriorated electrical conduction between electrodes and conductors.
Innovation Solution
The semiconductor device design includes electrodes with a base portion and a columnar portion, where the second electrode, closer to the periphery, has a larger area and height than the first electrode, providing increased bonding strength and resistance to warping by embedding into the bonding layer during reflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the electrodes are temporarily adhered to the conductor via a bonding layer and the bonding layer is melted by reflowing, then the semiconductor element is bonded to the conductor, but thermal stress causes the semiconductor element to warp upward in the thickness direction
Solution Approach 1:
The patent applies local quality by making the columnar portions of electrodes at different locations have different cross-sectional areas. Specifically, electrodes closer to the periphery (second electrodes) have larger columnar portions than those at the center (first electrodes). This non-uniform distribution provides greater bonding strength at the periphery where warping stress is more severe, effectively counteracting the upward warping caused by thermal stress during reflowing.
Solution Approach 2:
The patent changes the parameter of electrode cross-sectional area based on location. The columnar portions of second electrodes (peripheral) have larger cross-sectional areas than those of first electrodes (central). This parameter variation allows the bonding structure to better resist warping forces at the periphery while maintaining appropriate bonding strength throughout the semiconductor element.
2Duration of action of stationary object
If the semiconductor element warps considerably, then the bonding process is completed, but the contact area between the bonding layer and each of the electrodes located relatively close to the periphery becomes smaller
Solution Approach 1:
The patent addresses the contact area reduction during warping by providing larger columnar portions at peripheral electrodes. These enlarged columnar portions ensure that even when the semiconductor element warps upward during reflowing, the second electrodes (closer to periphery) maintain sufficient contact area with the bonding layer, preventing deterioration of electrical conduction.
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
This configuration reduces warping and maintains effective electrical conduction by increasing the bonding strength and anchoring effect, preventing stress concentration and contact area reduction.
Implementation Method 1
the bonding layer is melted by ref lowing
Implementation Method 2
Such ref lowing produces thermal stress in the semiconductor element
Data Source
AI summary
A semiconductor device includes a conductor, a semiconductor element, and a bonding layer. The conductor has obverse surfaces and reverse surfaces facing away from each other in a thickness direction. The semiconductor element has a body layer and electrodes projecting toward the obverse surfaces from a side of the body layer that opposes the obverse surfaces in the thickness direction. The bonding layer bonds the obverse surfaces and the electrodes. Each electrode has a base portion in contact with the body layer and a columnar portion projecting from the base portion and in contact with the bonding layer. The electrodes include a first electrode and a second electrode located closer to the periphery of the body layer than is the first electrode as viewed in the thickness direction. The second electrode is larger in area of the columnar portion than the first electrode, as viewed in the thickness direction.