Multilayer Electronic Structure With Patterned Via Posts
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Solution Overview
Problem
The 'drill & fill' method for creating vias in IC substrates and interposers is limited by low throughput, high costs, difficulty in producing high-density vias of varying sizes and shapes, rough side walls, tapering, dimpling, and overfill issues, which hinder the fabrication of high-density, reliable, and cost-effective electronic support structures.
Innovation Solution
The use of pattern plating and panel plating technologies to deposit copper via posts in a photoresist pattern, followed by laminating a dielectric material, allowing for the creation of smooth, non-tapering trenches and enabling the fabrication of a wide range of via shapes and sizes, with the option to build up multilayer structures and achieve coreless laminar structures for improved reliability and planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill & fill method is used to create vias, then vias can be formed through the dielectric substrate, but the throughput rate is limited and fabrication costs become prohibitive
Solution Approach 1:
The patent replaces the mechanical laser drilling process with a chemical deposition process. Instead of using lasers to drill holes through the dielectric, the invention uses electroless copper deposition to directly form vias and via posts through chemical reduction of copper ions onto a catalyzed substrate, eliminating the need for mechanical drilling and subsequent filling operations
Solution Approach 2:
The patent introduces a catalyst layer (typically palladium or palladium alloy) as an intermediary between the dielectric substrate and the copper deposition process. This catalyst layer enables selective electroless copper deposition by providing catalytic sites for copper ion reduction, allowing precise via formation without mechanical drilling
2Manufacturing precision
If laser drilling is used to create vias, then vias can be formed, but the side walls become rough and taper inwards reducing effective diameter
Solution Approach 1:
The patent replaces mechanical laser drilling with chemical electroless deposition. The electroless copper deposition process creates smooth, uniform via walls through controlled chemical reduction, eliminating the rough, tapered walls produced by laser drilling. The deposition rate and via geometry are controlled by chemical parameters rather than mechanical energy input
Solution Approach 2:
The patent changes the fundamental process parameters from mechanical (laser power, pulse duration, focus position) to chemical (copper ion concentration, pH, temperature, catalyst density). This parameter transformation enables precise control of via diameter and wall smoothness through solution chemistry rather than mechanical constraints
3Manufacturing precision
If copper electroplating is used to fill drilled vias, then vias can be filled with copper, but dimpling and overfill occur creating difficulties for subsequent via stacking
Solution Approach 1:
The patent replaces electroplating with electroless deposition. The electroless process deposits copper uniformly throughout the via without the cathodic polarization effects that cause dimpling and overfill in electroplating. This results in flush, uniform via surfaces that are ideal for subsequent via stacking and planarization operations
Solution Approach 2:
The electroless deposition process is self-regulating through autocatalysis. The copper deposition rate is automatically controlled by the available catalyst sites and copper ion diffusion, preventing overfill. The process naturally stops when the via is filled without requiring external control, eliminating dimpling and overfill defects
4Adaptability or versatility
If the drill & fill method is used, then vias can be created, but it is difficult to produce high density vias of different sizes and shapes in close proximity
Solution Approach 1:
The patent uses photoresist patterning to define via locations and geometries, then applies uniform electroless copper deposition. By changing the photoresist pattern parameters (opening size, shape, spacing), any via geometry can be created with high precision and density. The deposition process itself remains uniform, ensuring consistent via quality across the substrate
Solution Approach 2:
The patent performs preliminary photoresist patterning to define via locations and geometries before copper deposition. This preliminary structuring step allows precise control of via size, shape, and spacing, enabling high-density arrays of varied via geometries that would be impossible to achieve with direct laser drilling
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 enables cost-effective fabrication of high-density, reliable interconnects with minimal inductance and capacitance, allowing for the creation of complex electronic structures with improved electrical performance and reduced warping, facilitating the production of thinner, more powerful electronic components.
Implementation Method 1
a first transmission line comprising a lower continuous metallic layer and further comprising a row of metallic via posts coupled to the continuous metal layer
Implementation Method 2
the transmission line is separated by a dielectric material from an underlying reference plane
Data Source
AI summary
A signal carrier for carrying a signal in a direction within the X-Y plane of a multilayer composite electronic structure comprising a plurality of dielectric layers extending in an X-Y plane, the signal carrier comprising a first transmission line comprising a lower continuous metallic layer and further comprising a row of metallic via posts coupled to the continuous metal layer, wherein the transmission line is separated by a dielectric material from an underlying reference plane.