Patterned Adhesive Bonding for 3D Interconnects
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Solution Overview
Problem
The Vias-Last approach for forming 3D metal interconnects in stacked IC chips is complicated by the difficulty of bottom clear etching, which increases with material thickness and aspect ratio, requiring complex etch masks and processes.
Innovation Solution
A method involving patterned photoresist or adhesive material is used to bond substrates, where through-holes are formed in one substrate and metallizations are deposited to connect with components of another substrate, eliminating the need for bottom clear etching by using a patternable adhesive like SU8 to align and attach the substrates before via formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Vias-Last approach is used to form 3D metal interconnects, then interconnect formation is achieved, but the process complexity increases due to difficult bottom clear etching
Solution Approach 1:
The adhesive layer is patterned before bonding occurs, allowing the via openings to be defined in advance. This preliminary patterning eliminates the need for complex bottom clear etching after bonding, as the adhesive pattern already provides the necessary openings for via formation.
Solution Approach 2:
Instead of forming vias after bonding (Vias-Last), the invention inverts the sequence by patterning the adhesive to define via openings before bonding. This allows via formation to occur more easily after bonding without requiring difficult etching through thick adhesive layers.
2Manufacturing precision
If bottom clear etching is performed to remove adhesive from via regions, then via openings are created, but the etching difficulty increases with material thickness and aspect ratio
Solution Approach 1:
The adhesive is patterned to define via openings before bonding, so the openings are already created in the adhesive layer. This eliminates the need for difficult bottom clear etching after bonding, as the via pathways are already established by the patterned adhesive structure.
3Manufacturing precision
If etch masks are used to protect certain areas during etching, then selective etching is achieved, but the process complexity and integration issues increase
Solution Approach 1:
The invention extracts the masking function from a separate etch mask layer and integrates it directly into the adhesive layer through patterning. The patterned adhesive itself serves as the mask, eliminating the need for additional etch mask materials and simplifying the overall process.
Solution Approach 2:
The adhesive layer serves multiple functions: it provides bonding adhesion, defines via openings through patterning, and acts as the etch mask. This multi-functionality eliminates the need for separate etch mask layers and reduces process complexity.
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 simplifies the bonding process, allows for thicker bond lines, and decouples via formation from post-bonding processes, reducing integration complexity and eliminating the need for adhesive etching, while enabling flexible via formation and insulation.
Implementation Method 1
a patternable substance disposed between the first substrate and the second substrate and adhering the first substrate and the second substrate together
Data Source
AI summary
An electronic package and method and system for forming the electronic package. The electronic package has a first substrate including a first electronic device and including through-holes extending through an entire thickness of the first substrate. The electronic package has a second substrate bonded to the first substrate, metallizations formed in the through-holes of the first substrate to connect to components of the first electronic device, and a patternable substance disposed between the first substrate and the second substrate and adhering the first substrate and the second substrate together in regions apart from the metallizations. The method and system form through-holes extending through an entire thickness of the first substrate, deposit and pattern an adherable substance on the second substrate in a pattern having openings which expose connections for a second electronic device of the second substrate, align and attach the first substrate and the second substrate together, and form metallizations in the through-holes to connect to the connections for the second electronic device.