Liquid Phase Deposition for High Aspect Ratio Hole Metallization
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Solution Overview
Problem
Current methods for metallizing holes in electronic modules with high aspect ratios (R > 10) face challenges in achieving uniform metal layer deposition, particularly for small diameters, leading to incomplete and non-uniform metal coverage.
Innovation Solution
A multi-layer liquid phase deposition process involving a hermetic enclosure with controlled pressure cycles, including degassing, filling, and explosive evaporation, along with preliminary steps like cleaning, etching, and activation, to ensure uniform metal layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If copper wires are embedded in holes and connected by wire bonding, then electrical connections can be established, but the method is time-consuming and costly
Solution Approach 1:
The patent replaces the mechanical wire bonding process with a chemical deposition process. Liquid precursor solutions containing copper salts are applied to the holes, and copper metal is deposited electrochemically to form conductive pathways. This substitution eliminates the need for mechanical wire manipulation and bonding, significantly reducing manufacturing time and complexity.
Solution Approach 2:
The patent changes the physical and chemical parameters of the deposition process to optimize copper formation. By controlling parameters such as precursor solution concentration, deposition temperature, and chemical composition, the process achieves reliable copper metal deposition in the holes, transforming the connection method from mechanical to chemical while improving productivity.
2Manufacturing precision
If holes are metallised by electroplating, then copper layers can be formed, but the holes must be filled to the top which increases copper consumption
Solution Approach 1:
The patent employs electroless deposition rather than electroplating, fundamentally changing the deposition mechanism. In electroless deposition, copper is deposited through a chemical reduction reaction that occurs uniformly throughout the hole volume, allowing precise control over the deposition depth and thickness. This enables forming conductive pathways without necessarily filling holes to the top, reducing copper consumption while maintaining manufacturing precision.
Solution Approach 2:
The patent replaces the electroplating process with an electroless chemical deposition process. This substitution allows for more uniform and controlled copper distribution within the holes, as the chemical reaction occurs throughout the solution-hole interface rather than requiring electrical current flow. This results in more efficient copper utilization and reduced material waste.
3Manufacturing precision
If deep holes are metallised, then connections can be made in advanced technology nodes, but conventional electroplating cannot fill deep holes uniformly
Solution Approach 1:
The patent replaces conventional electroplating with electroless chemical deposition, which is particularly effective for deep holes. The chemical deposition mechanism allows the precursor solution to penetrate deep holes uniformly and deposit copper throughout the entire depth, achieving consistent metallization that electroplating cannot accomplish due to electrical field distribution limitations in deep structures.
Solution Approach 2:
The patent changes the deposition methodology from electrochemical to chemical reduction, enabling uniform metal formation in deep holes. By optimizing parameters such as precursor solution composition, temperature, and deposition time, the process achieves uniform copper distribution throughout the full depth of deep holes, making it suitable for advanced technology nodes with high aspect ratio structures.
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 method achieves uniform and complete metal layer deposition on the walls of holes with high aspect ratios, improving the thickness and concentration of the metal layer, overcoming the limitations of conventional techniques.
Implementation Method 1
The method comprises the steps of providing a substrate with holes to be metallised and applying a liquid precursor solution to the substrate, the liquid precursor solution comprising a solvent and a metal salt, drying the liquid precursor solution, and sintering the dried liquid precursor solution in an atmosphere of nitrogen or inert gas
Implementation Method 2
drying the liquid precursor solution
Implementation Method 3
sintering the dried liquid precursor solution in an atmosphere of nitrogen or inert gas to form copper metal
Implementation Method 4
the sintering step comprises heating the substrate to a temperature between 90°C and 200°C
Data Source
Figure 1a~1b
Figure 2~3
Figure 4
AI summary
The invention relates to a method for the liquid phase deposition of metal layers in holes (11) of an electronic module (10) arranged in a tight enclosure (1), using a chemical liquid (4) comprising metal compounds for forming a metal layer. The depth P and diameter D of the holes are such that D>80 µm and P/D > 10, and the method comprises at least one cycle (Cyc) comprising the following sub-steps: M1) pressurising the enclosure at a predetermined pressure P0 and filling the enclosure with the liquid; M2) degassing the holes by pressurising the enclosure at a lower pressure P1, where P1<P0; M3) repressurising the enclosure at the first pressure P0 and filling the enclosure with the liquid; M4) depositing a metal layer obtained from the liquid in the holes; M5) emptying the liquid from the enclosure; M6) explosively evaporating the liquid remaining in the holes by pressurising the enclosure at a lower pressure P2, where P2<P1<P0, and repeating, at least once, the cycle (Cyc) comprising the sub-steps M1 to M6 in order to iteratively obtain a new metal layer.