Composite Interposer Counter-Deformation for LSI Bridge Reliability
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Solution Overview
Problem
Fan-out packages with embedded local silicon interconnect bridges are prone to die cracks, underfill delamination, and deformation during thermal compression bonding due to thermal expansion mismatch and mechanical stress, which affects their durability and reliability.
Innovation Solution
Incorporating metallic stress relief structures, such as counter-stress structures with metal vias and plates, into the composite interposer to redistribute mechanical stress and mitigate deformation around the local silicon interconnect bridge, thereby enhancing the interposer's durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal compression bonding is used to connect the interposer and electronic component, then mechanical and electrical connection is achieved, but the local silicon interconnect bridges deform due to heat and pressure
Solution Approach 1:
Metallic counter-deformation structures are formed in the interposer before the thermal compression bonding process. These structures are strategically positioned to apply counter-stress that anticipates and offsets the deformation forces that will be applied during bonding, thereby preventing shape change in the local silicon interconnect bridges while still achieving reliable mechanical and electrical connections
2Productivity
If local silicon interconnect bridges are used to shorten signal paths, then input-output bandwidth and power efficiency increase, but the interposer becomes prone to die cracks and underfill delamination
Solution Approach 1:
Metallic counter-deformation structures are selectively formed in specific regions of the interposer where local silicon interconnect bridges are located. This localized approach provides targeted stress relief and support precisely where the thin interconnect bridges are most vulnerable to deformation, die cracks, and underfill delamination, while maintaining the signal path shortening benefits without compromising overall interposer durability
3Strength
If the interposer is heated and pressurized during thermal compression bonding, then bonding between components is achieved, but mechanical stress causes deformation in the interconnect structures
Solution Approach 1:
Metallic counter-deformation structures with higher mechanical strength and thermal stability are integrated into the interposer to act as counterweights against the applied bonding pressure. These structures are positioned to directly oppose the stress vectors generated during thermal compression bonding, absorbing and redistributing the mechanical load away from the vulnerable local silicon interconnect bridges, thereby enabling strong bonding without interconnect deformation
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 use of metallic stress relief structures increases the metal density around the local silicon interconnect bridge, effectively countering mechanical stress and improving the composite interposer's reliability and durability, reducing the likelihood of deformation and enhancing performance.
Implementation Method 1
thermal compression bonding. This process involves heating the interposer and the electronic component to be connected to it, and then applying pressure to bond them together. The heat and pressure may cause the local silicon interconnect bridges to deform
Data Source
AI summary
A composite interposer includes a local-silicon-interconnect-containing (LSI-containing) interposer that includes a local silicon interconnect (LSI) bridge; and an organic interposer located on the LSI-containing interposer, including redistribution dielectric layers embedding redistribution wiring interconnects and a metallic counter-deformation structure. The metallic counter-deformation structure includes a plurality of metallic via structures; a first metallic plate located on a first side of the plurality of metallic via structures; and a second metallic plate located on a second side of the plurality metallic via structures and vertically spaced from the first metallic plate.