3D Electronic Package Adhesive Layer via Formation
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Solution Overview
Problem
Conventional 3D electronic packaging methods face challenges in forming interconnects with high aspect ratios, requiring complex etching steps and high bonding conditions, which can lead to gaps and inefficiencies, especially in the 'vias last' approach.
Innovation Solution
A method involving a first intermediate layer with a higher viscosity for patterning, followed by a lower viscosity un-patterned adhesive layer for bonding substrates, allowing for easier alignment and deposition of conductive material through vias, reducing the need for high bonding forces and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching and metallization steps are used to form high aspect ratio interconnects, then interconnect formation is achieved, but the process complexity increases and bonding conditions become more challenging
Solution Approach 1:
The adhesive layer is applied and patterned before substrate bonding, creating pre-formed via openings that eliminate the need for complex post-bonding etching steps. This preliminary preparation of interconnect pathways simplifies the overall manufacturing process while maintaining precision.
Solution Approach 2:
The adhesive material is selectively removed from via regions through the patterning process, extracting unnecessary adhesive to create clear pathways for interconnect formation. This extraction eliminates the need for subsequent complex etching operations.
2Strength
If high bonding forces and temperatures are applied to bond substrates, then substrate bonding is achieved, but bond-line gaps and defects increase
Solution Approach 1:
The adhesive layer's viscosity is modified through temperature and composition control, allowing it to remain flowable during bonding to fill gaps, then crosslink to provide structural strength. This parameter change enables gap filling at lower bonding forces and temperatures.
Solution Approach 2:
The adhesive layer serves as an intermediary material between substrates that actively flows to fill bond-line gaps during the bonding process, mediating the interface to eliminate voids and improve bonding quality without requiring high forces or temperatures.
3Manufacturing precision
If photo-definable adhesive layer is patterned to create via openings, then interconnect pathways are formed, but adhesive cross-linking increases viscosity making bonding more difficult
Solution Approach 1:
The adhesive layer is segmented into two functional regions: a patterned photo-definable adhesive for via formation, and an un-patterned non-photo-definable adhesive for bonding. This segmentation allows each region to optimize its properties - the patterned region provides precision via openings while the un-patterned region maintains low viscosity for easy bonding.
Solution Approach 2:
Different regions of the adhesive system have different properties: the patterned photo-definable adhesive region provides structural definition and via formation, while the un-patterned non-photo-definable adhesive region provides flowability and gap-filling capability 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
This approach minimizes bond-line gaps and simplifies interconnect metallization, enabling more reliable and efficient 3D electronic package fabrication with lower bonding requirements.
Implementation Method 1
bonding the first substrate and the second substrate together by bringing the second substrate into contact with the second intermediate layer and applying a force to at least one of the first substrate and the second substrate while heating the second intermediate layer
Implementation Method 2
heating the second intermediate layer
Implementation Method 3
forming an interconnect in contact with the contact pad by depositing an electrically conductive material through the via and the opening
Data Source
AI summary
An electronic package may be fabricated by forming a first layer of insulating material on a first substrate such that the first layer covers a contact pad; forming an opening through the first layer to expose the contact pad; forming an un-patterned second layer on the first layer, the second layer including an adhesive having a viscosity less than that of the first layer, wherein a region of the second layer obstructs the contact pad; removing the region to re-expose the contact pad; aligning a second substrate with the first substrate such that a via of the second substrate is aligned with the opening; bonding the first substrate and the second substrate together at the second layer; and forming an interconnect in contact with the contact pad by depositing a conductive material through the via and the opening.