Vapour-Deposited Passivation Layer for Metallic Surfaces
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Solution Overview
Problem
Existing passivation layers for metallic surfaces are either permanent, difficult to remove, or result in non-uniform thickness, leading to challenges in preventing oxidation and contamination during processing steps, especially in applications like electronic device fabrication.
Innovation Solution
A method involving the deposition of a passivation layer comprising an organic layer and an inorganic layer on a metallic surface, specifically using vapour deposition techniques, where the organic layer is formed from a precursor with specific functional groups that chemisorb onto the surface and the inorganic layer is deposited using atomic layer deposition, allowing for selective removal at elevated temperatures or mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent passivation layer (e.g., alumina) is deposited directly onto a metallic surface to suppress oxidation, then the oxidation resistance is improved, but the layer becomes difficult and time-consuming to remove, requiring aggressive chemical etching or mechanical polishing
Solution Approach 1:
The passivation layer is segmented into multiple functional layers: an organic passivation layer (first layer) that provides oxidation resistance and can be selectively removed, and an inorganic barrier layer (second layer) that provides additional protection. This segmentation allows the organic layer to be removed without aggressive etching while the inorganic layer remains for continued protection.
Solution Approach 2:
The invention changes the chemical composition and properties of the passivation layer by using organic materials with specific functional groups (oxygen, nitrogen, phosphorus, sulphur, selenium, tellurium, or silicon) that can be deposited by vapour deposition. These organic layers have different removal characteristics compared to traditional inorganic passivation layers, enabling selective removal at lower temperatures or with milder chemicals.
2Reliability
If OSP layers are deposited to inhibit oxidation prior to soldering, then the passivation function is achieved, but the layers have non-uniform thickness and can contaminate the substrate in subsequent processing steps
Solution Approach 1:
The invention replaces traditional OSP deposition methods with vapour deposition techniques (physical vapor deposition or chemical vapor deposition). This substitution provides better control over layer thickness and uniformity compared to conventional OSP application methods, resulting in more consistent passivation layers across the substrate surface.
Solution Approach 2:
The invention uses a composite structure combining organic passivation materials with specific functional groups that provide both oxidation suppression and improved thickness uniformity. The organic layers can be deposited with better control over thickness distribution, reducing the thick and non-uniform characteristics of traditional OSP layers.
3Ease of manufacture
If the thickness of a passivation layer is decreased to reduce contamination risk, then the removal ease is improved, but the oxidation resistant characteristics may be compromised
Solution Approach 1:
The invention uses a composite passivation system with an organic layer and an inorganic barrier layer. The organic layer can be made thinner and removed more easily, while the inorganic layer provides continued oxidation protection. This composite approach maintains oxidation resistance even when the total thickness is reduced or when the removable organic portion is thin.
Solution Approach 2:
Different regions of the passivation system have different properties: the organic layer is designed for ease of removal and initial protection, while the inorganic layer provides durable, thin-barrier protection. Each layer is optimized for its specific function, allowing the overall system to achieve both thinness and effectiveness.
4Duration of action of stationary object
If a passivation layer is designed to suppress oxidation over a prolonged period (e.g., during storage), then the oxidation resistance is improved, but the layer becomes difficult to remove selectively when desired
Solution Approach 1:
The passivation system is segmented into an organic layer that can be selectively removed and an inorganic layer that provides long-term protection. The organic layer serves as a temporary, removable passivation layer for storage and processing, while the inorganic layer provides durable, long-lasting protection. This segmentation allows the system to provide prolonged oxidation suppression while maintaining selective removability when needed.
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 passivation layer effectively inhibits oxidation at room temperature while being selectively removable, reducing processing steps and minimizing material costs, with improved uniformity and reduced risk of contamination during subsequent processing.
Implementation Method 1
depositing at least one organic layer onto the metallic surface by vapour deposition
Implementation Method 2
the first functional group is adsorbed onto the metallic surface
Implementation Method 3
depositing at least one inorganic layer onto the organic layer by vapour deposition
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
According to the present invention there is provided a method of forming a passivation layer on a substrate. The method comprises the steps of: a) providing a substrate in a processing chamber, the substrate comprising a metallic surface, wherein the metallic surface is a copper, tin or silver surface, or an alloyed surface comprising one or more of copper, tin or silver; b) depositing at least one organic layer onto the metallic surface by vapour deposition, the organic layer formed from an organic precursor comprising: a first functional group comprising at least one of: oxygen, nitrogen, phosphorus, sulphur, selenium, tellurium, or silicon; and a second functional group selected from hydroxyl (-OH) or carboxyl (COOH); wherein the first functional group is adsorbed onto the metallic surface; and c) depositing at least one inorganic layer onto the organic layer by vapour deposition, wherein the second functional group acts as an attachment site for the inorganic layer.