Atmospheric Plasma Cleaning for Direct Bonding Chip Surfaces
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the contamination of die surfaces during die-to-wafer bonding due to adhesive films and silicone membranes, leading to hydrophobic surfaces and weak bonds, which affects throughput and yield in heterogeneous 3D-IC integration.
Innovation Solution
A method using atmospheric plasma to clean and passivate chip surfaces at ambient conditions, employing plasma-activated radical-enriched gases like He and O2, He and H2, or He, O2, and H2 mixtures to remove molecular contaminants and enhance surface hydrophilicity, enabling direct bonding without vacuum chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum plasma systems are used for cleaning die surfaces, then cleaning effectiveness is improved, but processing time increases due to pump down and vent requirements
Solution Approach 1:
The patent changes the operating pressure parameter from vacuum to atmospheric conditions, eliminating the need for pump down and vent cycles while maintaining effective plasma cleaning through atmospheric pressure plasma generation
Solution Approach 2:
The patent replaces the vacuum mechanical system with an atmospheric plasma system that operates at ambient pressure, substituting the vacuum chamber mechanism with a direct atmospheric plasma generation approach using dielectric barrier discharge
2Ease of manufacture
If carrier wafers are used for individual die processing, then cleaning compatibility is improved, but device complexity increases
Solution Approach 1:
The patent extracts the cleaning process from the vacuum plasma system requirements by implementing atmospheric plasma cleaning, allowing individual dies to be cleaned directly without needing carrier wafers or vacuum chamber accommodation
Solution Approach 2:
The atmospheric plasma system enables self-contained cleaning of individual dies at ambient conditions, making the process self-sufficient without requiring carrier wafer intermediaries or vacuum system infrastructure
3Ease of operation
If adhesive films or silicone membranes are used for die support, then handling is improved, but surface contamination increases
Solution Approach 1:
The patent applies atmospheric plasma cleaning as a preliminary treatment step before bonding to remove contamination from adhesive films or silicone membranes, restoring surface cleanliness without requiring alternative handling methods
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 method effectively reduces hydrocarbon and silicone residues, enhancing bond strength and improving throughput by creating clean, hydrophilic surfaces, resulting in stronger chip-to-substrate adhesion and reducing contamination-related issues.
Implementation Method 1
directing plasma-activated radical-enriched gas flow at substantially ambient atmospheric conditions to the contaminated bonding surface
Implementation Method 2
The plasma-activated radical-enriched gas both removes molecular contaminants from the contaminated bonding surface
Implementation Method 3
The plasma-activated radical-enriched gas both removes molecular contaminants from the contaminated bonding surface resulting in a clean bonding surface and also passivates the clean bonding surface
Data Source
AI summary
An atmospheric pressure plasma system is used to clean surface contaminants from chip surfaces prior to direct bonding them onto wafers. The surface contaminants include contact residue transferred from common adhesive films and silicone membranes used in semiconductor fabrication and packaging. WCA and FTIR data confirm the transfer of hydrocarbon and silicone contaminant residue that reduce hydrophilicity and surface energy. The atmospheric plasma treatment of the chip surfaces significantly reduces or eliminates these contaminants and results in stronger bonds than the untreated chip surfaces.