Covalent Bonding Layer for Low-Temperature Wafer Joining
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Solution Overview
Problem
Conventional substrate bonding processes for semiconductor wafers are complex, expensive, and suffer from limited bonding strength, queue time lag, and copper oxidation issues, particularly in direct and hybrid bonding techniques.
Innovation Solution
A method involving alkyne- and azide-functionalized bonding layers on substrates that form a triazole linkage through a cycloaddition mechanism at low temperatures, eliminating the need for plasma activation and hydration processes, resulting in a stronger, non-reversible covalent bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional direct or hybrid bonding techniques are used, then substrate bonding can be achieved, but the process becomes complex and expensive due to plasma activation and hydration steps
Solution Approach 1:
The patent extracts and removes the plasma activation and hydration steps from the conventional bonding process. By using self-assembled monolayers with reactive functional groups that directly bond upon contact, the complex multi-step process is simplified to a single contact step, reducing process complexity while maintaining bonding reliability
Solution Approach 2:
The patent changes the chemical parameters of the bonding surface by introducing self-assembled monolayers with specific functional groups (azide, alkyne, epoxide) that enable direct covalent bonding. This parameter change eliminates the need for plasma and hydration treatments, simplifying the process while ensuring reliable bonding
2Reliability
If plasma activation and hydration processes are implemented, then bonding capability is enhanced, but queue time lag increases due to multiple processing steps
Solution Approach 1:
The patent applies preliminary action by pre-forming self-assembled monolayers with reactive functional groups on the bonding surfaces before the actual bonding event. This preliminary functionalization eliminates the need for time-consuming plasma activation and hydration steps at the time of bonding, significantly reducing queue time while maintaining enhanced bonding capability
Solution Approach 2:
The patent extracts the time-consuming plasma activation and hydration steps from the bonding process timeline, replacing them with a single contact step where pre-functionalized surfaces bond directly, thereby eliminating queue time lag
3Reliability
If conventional bonding interfaces are used, then substrate bonding is achieved, but bonding strength is limited and may be reversible
Solution Approach 1:
The patent uses composite materials by combining self-assembled monolayers with specific functional groups (azide, alkyne, epoxide) that form covalent bonds with the substrate and with each other. This composite approach creates a multi-layer bonding interface with superior strength and irreversibility compared to conventional single-material bonding interfaces
Solution Approach 2:
The patent changes the bonding interface parameters by introducing covalent bond-forming functional groups that create strong, irreversible chemical bonds. This parameter change transforms the bonding mechanism from physical adhesion to chemical bonding, significantly enhancing bonding strength
4Reliability
If hydration step is applied to enhance bonding, then bonding capability improves, but copper-based conductive features oxidize and resistivity increases
Solution Approach 1:
The patent extracts and eliminates the hydration step from the bonding process, replacing it with direct contact bonding of pre-functionalized surfaces. This removal prevents water exposure that would cause copper oxidation, eliminating the harmful effect while maintaining improved bonding capability through covalent bond formation
Solution Approach 2:
The patent creates an inert environment by using self-assembled monolayers that enable bonding without water exposure. The reactive functional groups on the monolayers allow covalent bonding to occur in the absence of moisture, preventing copper oxidation while maintaining bonding capability
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 enhances bonding strength, reduces processing complexity and cost, and minimizes queue time by forming a stable, non-reversible covalent bond between substrates, while avoiding copper diffusion and oxidation.
Implementation Method 1
chemically reacting the alkyne moiety with the azide moiety through a cycloaddition mechanism, thereby forming a triazole moiety-linked layer at the interface
Implementation Method 2
When the bonding surfaces are brought into contact and a thermal treatment is applied, the moieties form a triazole linkage
Data Source
AI summary
A method includes providing a first substrate with a first surface including an alkyne moiety. The method includes providing a second substrate with a second surface including an azide moiety. The method further includes bonding the first substrate to the second substrate. The bonding of the first substrate to the second substrate includes making physical contact between the first surface and the second surface at an interface and chemically reacting the alkyne moiety with the azide moiety through a cycloaddition mechanism, thereby forming a triazole moiety-linked layer at the interface.