Through-Glass Via Metallization for High-Aspect-Ratio Filling
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Solution Overview
Problem
Conventional glass metallization processes face challenges in filling through glass vias with high aspect ratios, leading to incomplete plating, air gaps, and low yield due to uneven metal growth, which is exacerbated by thermal expansion differences and structural weaknesses.
Innovation Solution
A glass metallization process involving a stack of two glass substrates with seed layers, pre-lubrication, and electroplating from opposite sides to ensure complete via filling, using carbon dioxide and water to facilitate metal growth, and employing energy-removable or low-melting-point bonding layers to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electroplating is used to fill through glass vias with high aspect ratio, then the process is simple, but the metal material grows unevenly from upper and lower ends toward the center, causing air gaps and incomplete plating at the center
Solution Approach 1:
The patent inverts the conventional electroplating approach by introducing seed layers at the center of the via openings rather than relying on natural growth from upper and lower ends. This inversion enables metal material to grow from the center outward toward the upper and lower ends, eliminating air gaps and ensuring complete via filling even in high aspect ratio structures.
Solution Approach 2:
The patent applies preliminary action by forming seed layers at the center of the via openings before electroplating. These seed layers serve as starting points that facilitate controlled metal material growth from the center outward, preventing air gap formation and ensuring complete plating throughout the via structure.
2Ease of manufacture
If conventional electroplating is used for high aspect ratio vias, then the process is straightforward, but the plating speed is slow and production efficiency is low
Solution Approach 1:
The patent enhances plating speed by forming seed layers at the center of via openings before electroplating. These pre-formed seed layers serve as efficient nucleation sites that accelerate metal material deposition, enabling significantly faster plating speeds and improved production efficiency compared to conventional methods.
3Device complexity
If single glass substrate is used, then the structure is simple, but the substrate is prone to breakage affecting yield rate
Solution Approach 1:
The patent divides a single glass substrate into two separate glass substrates stacked together, with via openings formed through both substrates. This segmentation distributes mechanical stress and prevents breakage of individual substrates, thereby improving reliability and yield rate while maintaining structural integrity.
4Ease of manufacture
If metal material grows from upper and lower ends toward center, then the electroplating process is conventional, but thermal expansion differences cause cracking and damage to glass substrate
Solution Approach 1:
The patent inverts the conventional growth direction by forming seed layers at the center of via openings and enabling metal material to grow from the center outward toward the upper and lower ends. This reversal of growth direction eliminates thermal expansion differences that cause cracking and damage, as the metal grows away from the glass substrate boundaries rather than toward them.
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 complete via filling, increased plating speed by 200 times, improved yield, and reduced substrate cracking, enhancing productivity and structural support.
Implementation Method 1
an electroplating process is performed to form a conductive layer covering the seed layer
Implementation Method 2
introducing water liquid into the holding tank, wherein the water liquid reacting with carbon dioxide to produce carbonic acid
Implementation Method 3
a sputtering process is performed to form a seed layer to cover the surface of the glass substrate and the wall surface of the glass substrate in the via
Data Source
AI summary
The present invention relates to a glass metallization process for through glass vias with a high aspect ratio. The process includes a single-sided coating step, a bonding step, a drilling step, a pre-lubricating step and a metallization step; or a drilling step, a single-sided coating step, a bonding step, a pre-lubricating step and a metallization step. Since the walls of the first and second glass substrates, the first and second seed layers and a bonding layer at the vias have undergone a pre-lubricating process, it is easy for the growth of the metal material during the electroplating process. Also, the metal material grows outward from a center of the stacked structure of the first and second glass substrates to completely fill the vias, thereby being able to be applied to vias with a higher aspect ratio without creating air gaps, making the electroplating process simpler and improving the electroplating yield.