Conductive Via Precursor Planarization for Low-Resistance Substrates
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Solution Overview
Problem
Existing methods for forming conductive vias in miniaturized silicon substrates face challenges in achieving low connection resistance values due to poor planarity and high step heights, which are exacerbated by further wiring formation.
Innovation Solution
A method involving a metal paste composed of specific metal particles and a volatile solvent is used to form conductive vias, where the paste is applied, heated to remove solvent, and then fired, resulting in a conductive via with reduced step height and minimized cracks and voids, ensuring low connection resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper plating is performed on blind-vias to form through electrodes, then conductive vias can be formed, but the deposition rate is reduced and operation time increases
Solution Approach 1:
The patent replaces the electroplating process (electrical/chemical system) with a metal paste filling method involving screen printing, drying, and firing (mechanical/thermal system). This substitution eliminates the slow deposition rate and long operation time associated with electroplating while achieving reliable conductive via formation through the metal paste process.
Solution Approach 2:
The patent changes the fundamental parameters of the conductive via formation process by using metal paste containing copper powder, glass powder, and organic vehicle instead of electroplating solution. The process parameters involve screen printing, drying at specific temperatures, and firing at elevated temperatures, which fundamentally alters the formation mechanism and improves productivity.
2Reliability
If through-holes are filled with copper conductor paste and fired to form copper conductors, then conductive vias can be formed, but planarity is poor and step height is large
Solution Approach 1:
The patent applies local quality by using glass powder in the metal paste to create a glassy matrix that locally fills and smooths the through-hole structure during firing. This glassy phase forms a planar surface at the via opening while maintaining the conductive copper network inside, thereby improving planarity without compromising conductivity.
Solution Approach 2:
The patent employs composite materials by combining copper powder (conductive phase), glass powder (planarizing phase), and organic vehicle (binding phase) in specific ratios. The glass-copper composite structure provides both electrical conductivity and surface planarity, resolving the contradiction between these two requirements.
3Productivity
If miniaturization of through-hole inner diameter is pursued, then device integration is improved, but achieving sufficient conductivity becomes more difficult
Solution Approach 1:
The patent changes the particle size parameters of copper powder to achieve optimal results for miniaturized vias. By controlling the copper powder particle diameter within specific ranges (e.g., 0.5-2.0 μm), the paste can effectively fill small through-holes while maintaining sufficient conductivity. The glass powder content and particle size are also optimized to ensure proper filling and planarity in miniaturized structures.
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution of copper particles and glass phase within the via structure. The glassy matrix locally consolidates the copper particles at the via opening, ensuring low contact resistance even in miniaturized vias where geometric effects would normally increase resistance.
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 achieves a conductive via-containing substrate with low connection resistance values and excellent conductivity, even after wiring formation, by using a metal paste with a specific composition and processing steps to ensure planarity and minimize defects.
Implementation Method 1
step b of heating the metal paste part to remove a part of the volatile solvent
Implementation Method 2
step d of firing the conductive via precursor to form a conductive via
Data Source
AI summary
A method for manufacturing a conductive via-containing substrate is provided, the method including: step a of preparing a substrate provided with a hole and providing a metal paste part containing metal particles and a volatile solvent to cover at least a surface surrounding the hole of the substrate while an inside of the hole is filled with the metal paste part; step b of heating the metal paste part to remove a part of the volatile solvent; step c of removing a part of the metal paste part after heating to expose the surface to form a conductive via precursor in the hole, the conductive via precursor containing the metal particles and a residue of the volatile solvent and having a planarized exposed surface; and step d of firing the conductive via precursor.