Plating Pre-treatment for High Aspect Ratio Recesses
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Solution Overview
Problem
Conventional methods face challenges in forming a plating layer with sufficient adhesivity on the inner surfaces of recesses with high aspect ratios, such as TSVs, due to limitations with silane and titanium coupling agents, where silane agents have low adhesivity and titanium agents struggle with adsorption and degradation.
Innovation Solution
A pre-treatment method involving a silane coupling process by vacuum deposition for high coverage on inner surfaces and a titanium coupling process by spin-on for high adhesivity on outer surfaces, using different coupling agents based on required properties without the need for special masking techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a titanium coupling agent is used to improve adhesivity, then adhesivity of the metal film is improved, but it cannot be adsorbed onto the substrate by vacuum deposition process and takes very long time to complete
Solution Approach 1:
The substrate surface is divided into two regions (inner surface of recess and outer surface) and different coupling agents are applied to each region. The silane coupling agent is applied to the inner surface where vacuum deposition can achieve high coverage, while the titanium coupling agent is applied to the outer surface where high adhesivity is required but vacuum deposition is ineffective.
Solution Approach 2:
Different coupling agents with different properties are used for different locations on the substrate. The silane coupling agent provides high coverage on the inner surface of the recess, while the titanium coupling agent provides high adhesivity on the outer surface. This local differentiation resolves the contradiction by matching the right agent to the right location.
2Area of stationary object
If a silane coupling agent is used for vacuum deposition process, then high coverage can be attached on inner surface of recess, but the film may be separated by membrane stress due to low adhesivity
Solution Approach 1:
The substrate surface is segmented into regions requiring different properties. The silane coupling agent is used specifically for the inner surface of the recess where coverage is critical, while the titanium coupling agent is used for the outer surface where adhesivity is critical. This segmentation allows each agent to excel at its designated location.
Solution Approach 2:
The coupling requirements are made local rather than uniform. The inner surface of the recess requires high coverage (silane), while the outer surface requires high adhesivity (titanium). By making the coupling agent selection location-dependent, both coverage and adhesivity requirements are satisfied simultaneously.
3Ease of manufacture
If a single coupling agent is used for both inner and outer surfaces, then process simplicity is maintained, but insufficient adhesivity or coverage is achieved in at least one region
Solution Approach 1:
Instead of using a single coupling agent uniformly, the process segments the substrate into two regions and applies different coupling agents to each. This segmentation is achieved through a two-step process: first applying silane coupling agent to the inner surface, then applying titanium coupling agent to the outer surface, ensuring optimal performance in each region.
Solution Approach 2:
The coupling agent selection is made local rather than uniform across the entire substrate. The inner surface of the recess receives silane coupling agent for high coverage, while the outer surface receives titanium coupling agent for high adhesivity. This local differentiation ensures high plating quality without compromising process simplicity.
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 enables the formation of a uniform plating layer with enhanced adhesivity on both inner and outer surfaces of recesses, improving manufacturing efficiency and reducing processing time and agent consumption, while maintaining high-quality plating without defects.
Implementation Method 1
since the silane coupling agent can be adsorbed onto the substrate through the vacuum deposition process
Implementation Method 2
a self-assembled monolayer (SAM) is formed on the base by using a coupling agent
Implementation Method 3
a catalytic metal such as palladium particles is provided on the base with the self-assembled monolayer therebetween
Data Source
AI summary
A pre-treatment method for plating can form a plating layer having sufficient adhesivity on an inner surface of a recess and on a surface of a substrate at an outside of the recess even when the recess has a high aspect ratio. The pre-treatment method for plating includes a preparation process of preparing the substrate having the recess; a first coupling layer forming process of forming a first coupling layer 21a at least on the inner surface of the recess of the substrate by using a first coupling agent; and a second coupling layer forming process of forming a second coupling layer 21b at least on the surface of the substrate at the outside of the recess by using a second coupling agent after the first coupling layer forming process.