Interfacial Bonding Test Structure for 3D IC Delamination Risk
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Solution Overview
Problem
Semiconductor packages face challenges such as mechanical issues due to thermal expansion mismatch, leading to warpage, cracking, and delamination, particularly in high-performance 3-dimensional integrated circuits, which affect solder connections and overall package reliability.
Innovation Solution
The implementation of reinforcement structures, including stiffener rings and underfill materials, to enhance mechanical stability and compensate for thermal stresses, along with interfacial bonding test structures for evaluating bonding energies using a four-point bending test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3-dimensional integrated circuits are fabricated by placing chips over chips on a semiconductor wafer level, then integration density and bandwidth are improved, but mechanical issues such as warpage, cracking, and delamination occur due to thermal expansion mismatch between package components
Solution Approach 1:
An intermediate buffer layer is introduced between the semiconductor die and the substrate. This buffer layer has a coefficient of thermal expansion that is intermediate between the die and substrate, acting as a mediator to reduce thermal expansion mismatch and prevent mechanical defects such as warpage, cracking, and delamination during fabrication and operation of 3D integrated circuits
Solution Approach 2:
The patent employs composite material structures that combine materials with different thermal expansion coefficients in a layered configuration. This composite approach allows the structure to accommodate differential thermal expansion between components while maintaining mechanical integrity and reliability in high-density 3D integrated circuits
2Reliability
If reinforcement structures such as stiffener rings and underfill materials are added to enhance mechanical stability, then warpage and delamination are reduced, but device complexity increases
Solution Approach 1:
Instead of uniformly reinforcing the entire package structure, stiffener rings are strategically placed at specific locations where mechanical stress concentration is most likely to occur. This localized reinforcement approach provides necessary mechanical stability while minimizing the overall complexity and material usage compared to uniform reinforcement
3Reliability
If interfacial bonding test structures are implemented to evaluate bonding energies, then reliability of solder connections is improved, but manufacturing complexity increases
Solution Approach 1:
The test structure is segmented into distinct functional regions including bonding test areas and isolation areas. This segmentation allows the bonding evaluation function to be isolated in specific zones, enabling reliable measurement of interfacial bonding energies while containing the added manufacturing complexity to localized regions rather than affecting the entire device fabrication process
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
Improves co-planarity of solder connections, reduces warpage, and enhances the reliability of semiconductor packages by providing mechanical support and predicting interfacial bonding strengths, thereby ensuring stable electrical connections.
Implementation Method 1
interfacial bonding test structures that may be used in a four-point bending test to determine an interfacial bonding energy
Data Source
AI summary
An embodiment interfacial bonding test structure may include a first substrate having a first planar surface, a second substrate having a second planar surface that is parallel to the first planar surface, a first semiconductor die, and a second semiconductor die, each semiconductor die bonded between the first substrate and the second substrate thereby forming a sandwich structure. The first semiconductor die and the second semiconductor die may be bonded to the first surface with a first adhesive and may be bonded to the second surface with a second adhesive. The first semiconductor die and the second semiconductor die may be displaced from one another by a first separation along a direction parallel to the first planar surface and the second planar surface. The second substrate may include a notch having an area that overlaps with an area of the first separation in a plan view.