Curable Bonding Layer for Low-Complexity Semiconductor Bonding
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Solution Overview
Problem
Conventional wafer-to-wafer and chip-to-chip bonding processes are complex, expensive, and suffer from limited bonding strength, queue time limitations, and issues like copper oxidation and resistivity, particularly in direct or hybrid bonding techniques that rely on plasma activation and hydration processes.
Innovation Solution
A method involving the use of a thermally or photocurable bonding layer, such as disilacyclobutanes (DSCB), which forms covalent bonds without plasma activation or hydration, by applying thermal energy or UV radiation to create a stable, non-reversible bonding interface with reduced copper diffusion and lower dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma activation and hydration processes are used for substrate bonding, then bonding interface preparation is achieved, but queue time increases and bonding strength is limited
Solution Approach 1:
The patent removes plasma activation and hydration processes from the bonding sequence, extracting these steps entirely to eliminate their associated queue time delays while achieving bonding through direct thermal or UV curing of the bonding layer
Solution Approach 2:
The bonding layer is prepared in advance with photoinitiator or thermally curable groups incorporated into its composition before bonding occurs, allowing immediate curing upon contact without requiring prior plasma activation or hydration treatment of the substrate surfaces
2Reliability
If plasma activation is used to prepare bonding surfaces, then surface activation is achieved, but processing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates plasma activation equipment and process steps from the bonding workflow, replacing them with a chemically active bonding layer that cures through thermal or UV treatment, thereby reducing equipment requirements and process complexity
Solution Approach 2:
The bonding mechanism transitions from physical/chemical surface activation via plasma to chemical bond formation through curing of the bonding layer, changing the fundamental parameter of how adhesion is achieved from surface modification to molecular crosslinking
3Reliability
If hydration treatment is applied to bonding surfaces, then bonding capability is enhanced, but copper oxidation occurs increasing resistivity
Solution Approach 1:
The patent removes the hydration treatment step entirely from the process sequence, eliminating the source of moisture that causes copper oxidation while maintaining bonding capability through the curable bonding layer mechanism
Solution Approach 2:
The bonding layer acts as an intermediary between the substrates, providing the necessary chemical activity for bonding without requiring direct exposure of copper conductors to moisture or oxygen, thus protecting against oxidation while enabling adhesion
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 reduces processing complexity and cost, enhances bonding strength, and minimizes queue time by forming stable, non-polar covalent bonds, improving the reliability and efficiency of semiconductor substrate bonding.
Implementation Method 1
applying thermal energy or light to the bonding layer
Implementation Method 2
applying thermal energy or light to the bonding layer
Implementation Method 3
forming covalent bonds between substrates without the need for plasma activation or hydration
Data Source
AI summary
A method includes providing a first bonding surface on a first substrate, the first bonding surface including a bonding layer that is thermally curable or photocurable. The method includes providing a second bonding surface on a second substrate. The method includes bonding the first substrate to the second substrate by making physical contact between the first bonding surface and second bonding surface. The method further includes applying thermal energy or light to the bonding layer.