Glass Via Etching With Cationic Additives for Larger Waist Diameter
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Solution Overview
Problem
Laser-damage-and-etch processes for forming vias in glass-based articles result in vias with a narrow waist diameter, leading to hourglass shapes that pose challenges in downstream metallization processes.
Innovation Solution
Incorporating positive charge organic molecules, such as surfactants and polyelectrolytes, into the etching solution to retard the bulk etch rate of the glass surface while maintaining a higher etch rate within the damage track, thereby increasing the waist diameter of the vias and reducing the hourglass shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a conventional etching solution is used in the laser-damage-and-etch process, then the etching process is simple and fast, but the via waist diameter becomes significantly smaller than the opening diameters, resulting in an hourglass shape
Solution Approach 1:
A positive charge organic molecule acts as an intermediary substance in the etching solution. This molecule preferentially adsorbs onto the negatively charged glass surface, forming a protective layer that mediates between the etching environment and the glass surface. The intermediary layer retards bulk etching while allowing the damage track to etch at a higher rate, thereby improving via shape by increasing the waist diameter relative to the opening diameters.
2Productivity
If the bulk etch rate is high, then the etching process is efficient, but the via waist diameter decreases, creating challenges for downstream metallization processes
Solution Approach 1:
The etching solution is modified to create local quality differences in etching rate. The positive charge organic molecule creates a selective environment where the bulk glass surface experiences retarded etching due to adsorption of the organic molecule, while the laser-damaged regions maintain higher etch rates. This local differentiation allows the via waist to maintain a larger diameter while still achieving efficient overall etching through the glass substrate.
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 method enhances the waist diameter of vias, improving their shape and facilitating more reliable metallization processes without altering the glass composition or laser damage process, resulting in vias with a more cylindrical profile suitable for electronic device components.
Implementation Method 1
Glass surfaces generally have a negative charge when in contact with an etching solution. The positive charge organic molecule may be attracted to the negatively charged glass surface and form an etching inhibitor layer thereon. The etching inhibitor layer formed by the positive charge organic molecule may reduce the etching rate of the glass surface.
Implementation Method 2
forming a damage track through a bulk of the glass-based article extending from a first surface of the glass-based article to a second surface of the glass-based article
Data Source
AI summary
Methods of forming vias in a glass-based article by laser-damage-and-etch processes including etching solutions having positive charge organic molecules are disclosed. In some embodiments, a method of forming a via in a glass-based article includes forming a damage track through a bulk of the glass-based article extending from a first surface of the glass-based article to a second surface of the glass-based article, and applying an etching solution to the glass-based article to form the via. The etching solution includes at least one acid and a positive charge organic molecule. An etch rate at the first surface and the second surface is lower than an etch rate at the damage track.