Stacked Thin TGV Substrates for High-Aspect-Ratio Glass Vias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current laser-assisted etching processes for forming through glass vias (TGVs) are limited to low aspect ratios, making it difficult to achieve high aspect ratios in glass core substrates, particularly above 5:1, which hampers high-volume manufacturing and requires more complex and costly processes like atomic layer deposition and slower plating.
Innovation Solution
The use of multiple glass sub-cores with low aspect ratio TGVs stacked together to form higher aspect ratio features, employing conventional laser-assisted etching and physical vapor deposition for seed layer formation, and hybrid bonding to align and bond the sub-cores, allowing for the creation of high aspect ratio TGVs with visible seams and slight misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser assisted etching is used to form TGVs, then low aspect ratio TGVs (up to 5:1) can be formed, but high aspect ratio TGVs (above 5:1) cannot be formed in high volume manufacturing
Solution Approach 1:
The glass core is divided into multiple thin sub-core layers (e.g., three 50-micron layers instead of one 150-micron layer). Each sub-core layer contains a portion of the TGV stack. By segmenting the core, each TGV portion has a manageable aspect ratio (≤5:1) that can be formed using conventional laser-assisted etching in high volume manufacturing, while the stacked portions collectively achieve the desired high aspect ratio (15:1 or greater).
Solution Approach 2:
The solution transitions from forming TGVs in a single monolithic glass core to forming multiple TGV portions across separate sub-core layers that are then stacked vertically. This dimensional approach allows the TGV structure to extend through multiple bonded layers, achieving high aspect ratio without requiring any single etching process to create excessively deep via holes in thick glass.
2Manufacturing precision
If atomic layer deposition is used to form seed layers for high aspect ratio TGVs, then seed layer formation is possible, but manufacturing cost and process complexity increase
Solution Approach 1:
By segmenting the glass core into thin sub-core layers, each with low aspect ratio TGV portions, the patent enables the use of conventional sputtering processes for seed layer formation instead of requiring atomic layer deposition. The reduced aspect ratio in each sub-core allows sufficient seed layer coverage and conductivity using standard PVD techniques.
3Device complexity
If conventional sputtering is used for seed layer formation, then process simplicity is maintained, but high aspect ratio TGVs cannot be formed
Solution Approach 1:
Segmenting the glass core into thin sub-core layers enables conventional sputtering to effectively form seed layers on TGV portions with low aspect ratios (≤5:1). Each sub-core's TGV portions can be adequately coated by sputtering, and when stacked, these form the complete high aspect ratio TGV structure.
4Length of stationary object
If thicker glass cores are used, then substrate thickness requirements are met, but TGV formation becomes more difficult with aspect ratios above 5:1
Solution Approach 1:
The thick glass core is segmented into multiple thin sub-core layers, each thickness optimized to maintain TGV aspect ratios at or below 5:1. For example, a 150-micron core is divided into three 50-micron sub-cores, allowing conventional laser-assisted etching to effectively form TGV portions in each layer while achieving the required total core thickness through stacking.
Solution Approach 2:
Instead of forming one continuous TGV through a thick monolithic core, the patent forms multiple TGV portions across separate sub-core layers and stacks them vertically. This approach achieves the necessary total thickness while maintaining manufacturable aspect ratios in each individual layer.
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
Enables the formation of high aspect ratio TGVs up to 15:1 or greater, improving manufacturing throughput and reducing costs by using conventional processes and maintaining dimensional stability, while allowing for seamless glass-to-glass bonding and visible copper-to-copper interfaces.
Implementation Method 1
The laser exposure alters a microstructure and/or phase of the glass and renders the exposed areas more susceptible to an etching chemistry
Implementation Method 2
After the laser exposure, the wet etch is performed to form via openings
Implementation Method 3
employing conventional laser-assisted etching and physical vapor deposition for seed layer formation, and hybrid bonding to align and bond the sub-cores
Data Source
AI summary
Embodiments disclose a package substrate. In an embodiment, the package substrate comprises a core, where the core comprises: a first sub-core, where the first sub-core comprises a glass and a first through glass via (TGV), and a second sub-core, where the second sub-core comprises the glass and a second TGV. In an embodiment, the first TGV directly contacts the second TGV.