Sacrificial Dielectric Via Formation for Uniform HDI Plating
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Solution Overview
Problem
Current via fabrication methods in microelectronic packaging are limited in scalability and suitable dielectric materials, leading to challenges in achieving smaller via diameters and pitches required for high-density interconnects, with issues such as incomplete filling of via holes and non-uniform thicknesses due to high current density distribution during electroplating.
Innovation Solution
The use of a sacrificial photosensitive dielectric film to form via cavities in a non-photosensitive substrate dielectric, followed by deposition of a seed layer and simultaneous electroplating to fill the cavities, resulting in a contiguous metallization structure with uniform thickness and vertical sidewalls, overcoming the limitations of existing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating is used to fill via holes, then via formation is achieved, but non-uniform plating thickness and incomplete filling occur due to high current density distribution
Solution Approach 1:
A seed layer is deposited on the via hole walls before electroplating to establish a uniform conductive base. This preliminary action ensures that current distributes evenly during subsequent plating, preventing non-uniform thickness and incomplete filling.
Solution Approach 2:
The seed layer acts as an intermediary between the via hole substrate and the metal plating process. It mediates the current distribution, transforming the high current density problem into a controlled, uniform plating process that achieves both completeness and uniformity.
2Length of moving object
If via size is reduced to achieve high-density interconnects, then interconnect pitch is reduced, but fabrication scalability is limited
Solution Approach 1:
The via formation process is segmented into distinct steps: cavity formation, seed layer deposition, and controlled electroplating. This segmentation allows each step to be optimized independently, enabling scalable fabrication of smaller vias while maintaining quality control.
Solution Approach 2:
The invention changes key process parameters including cavity formation method, seed layer thickness, and plating conditions to enable via scaling. By adjusting these parameters, smaller via diameters and pitches can be achieved while maintaining manufacturing scalability and consistency.
3Adaptability or versatility
If current fabrication methods are used, then via formation is achieved, but suitable dielectric material selection is limited
Solution Approach 1:
The sacrificial dielectric material serves as a temporary intermediary structure that enables via cavity formation in diverse final dielectric materials. This intermediary approach allows the final dielectric to be selected based on electrical and mechanical requirements without being constrained by fabrication method limitations.
Solution Approach 2:
The invention changes the approach to dielectric material selection by decoupling the via formation process from dielectric material constraints. Through controlled cavity formation and seed layer deposition, the method adapts to various dielectric materials, expanding material suitability while maintaining manufacturing ease.
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 allows for the formation of high-density vias with uniform plating thickness and vertical sidewalls, enabling smaller via diameters and pitches, thus supporting advanced interconnect densities in microelectronic packages.
Implementation Method 1
The sacrificial photosensitive dielectric film is removed to create openings in the substrate dielectric and expose regions of the first metal structure
Implementation Method 2
simultaneous electroplating to fill the cavities, resulting in a contiguous metallization structure with uniform thickness
Data Source
AI summary
An apparatus, comprising a substrate comprising a dielectric, a conductor, comprising a via embedded within the dielectric, the via has a first end and a second end, and substantially vertical sidewalls between the first end and the second end, and a conductive structure extending laterally from the first end of the via over the dielectric, wherein the via and the conductive structure have a contiguous microstructure.