SAM Layer Reflective Moieties for Blind Microvia Drilling
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in forming fine line spaces and blind micro vias due to laser ablation, which leads to voided or underfilled vias and plating defects, limiting the adoption of next-generation packaging architectures and increasing costs and complexity.
Innovation Solution
A package substrate with a self-assembled monolayers (SAM) layer containing light-reflective moieties is used to protect the conductive surface from laser ablation, enabling low-cost high-resolution blind microvia drilling by reflecting excess laser energy and improving adhesion between dielectric and metal surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high energy intense light is used to ablate dielectric surface to form via openings, then via formation speed and resolution are improved, but metal pad ablation occurs causing voided vias and plating defects
Solution Approach 1:
An adhesion promoter layer is introduced as an intermediary between the dielectric and metal pad. This layer has selective ablation characteristics - it ablates easily to allow via formation while protecting the underlying metal pad from laser damage, thus preventing voided vias and plating defects while maintaining via formation efficiency
Solution Approach 2:
The laser parameters are optimized to exploit the different ablation thresholds of the adhesion promoter layer and metal pad. By controlling laser pulse duration, energy density, and repetition rate, the process selectively removes the adhesion promoter while preserving the metal pad, achieving both high productivity and manufacturing precision
2Manufacturing precision
If laser energy is reduced to prevent metal pad ablation, then via quality is improved, but via formation efficiency decreases
Solution Approach 1:
The adhesion promoter layer serves as a sacrificial intermediary that absorbs laser energy preferentially. This allows the use of higher laser energies for efficient via formation while the adhesion promoter protects the metal pad, thus maintaining both via quality and formation efficiency
Solution Approach 2:
The potential harmful effect of laser energy on the metal pad is converted into a beneficial process by using the adhesion promoter layer as a protective sacrificial layer. The laser energy that would otherwise damage the metal pad is instead used to efficiently remove the adhesion promoter, achieving fast via formation with high quality
3Strength
If adhesion promoter layer is used to improve adhesion between dielectric and metal pad, then adhesion strength is improved, but the layer is easily ablated by high energy laser sources
Solution Approach 1:
The weakness of the adhesion promoter layer (easy ablation) is converted into a strength by using it as a sacrificial protective layer. Its low ablation threshold becomes advantageous, allowing it to be selectively removed by laser while protecting the metal pad, thus turning a harmful characteristic into a beneficial process feature
Solution Approach 2:
The adhesion promoter layer provides localized protection only where needed - on the metal pad surface. It has different properties than the dielectric material, being more susceptible to laser ablation, which creates a selective removal mechanism that protects the metal while allowing via formation in the dielectric
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
The SAM layer with light-reflective moieties effectively prevents laser-induced damage, ensuring precise and cost-effective formation of fine line spaces and blind micro vias, enhancing the manufacturing process and reducing defects in semiconductor packages.
Implementation Method 1
A package substrate with a self-assembled monolayers (SAM) layer containing light-reflective moieties is used to protect the conductive surface from laser ablation, enabling low-cost high-resolution blind microvia drilling by reflecting excess laser energy
Implementation Method 2
The SAM layer with light-reflective moieties effectively prevents laser-induced damage, ensuring precise and cost-effective formation of fine line spaces and blind micro vias
Data Source
AI summary
Embodiments include a package substrate, a method of forming the package substrate, and a self-assembled monolayers (SAM) layer. The package substrate includes a SAM layer on portions of a conductive pad, where the SAM layer includes light-reflective moieties. The package substrate also includes a via on a surface portion of the conductive pad, and a dielectric on and around the via, the SAM layer, and the conductive pad, where the SAM layer surrounds and contacts a surface of the via. The SAM layer may be an interfacial organic layer. The light-reflective moieties may include a hemicyanine, a cyclic-hemicyanine, an oligothiophene, and/or a conjugated aromatic compound. The SAM layer may include a molecular structure having a first end group of a first monolayer, an intermediate group, a fifth end group of a second monolayer, and one or more of a first and second light-reflective moieties.