Plasma Surface Activation for Low-Temperature Substrate Bonding
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Solution Overview
Problem
Conventional substrate bonding techniques, such as direct and hybrid bonding, often require high pressure and temperature, leading to material damage and chemical state modifications at the bonding interface, necessitating the development of lower temperature bonding methods with excellent adhesion.
Innovation Solution
The method involves exposing the bonding surfaces to a plasma with a high electron density between 1×10^9 cm^-3 and 1×10^12 cm^-3 and an electron temperature less than 1 eV, generated using a slot-plane-antenna technique, and optionally including a reducing agent, to minimize ion energy and penetration depth, followed by annealing the bond interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bonding techniques use high pressure and temperature to achieve reliable bonding adhesion, then bonding strength is improved, but material damage and chemical state modifications at the bonding interface occur
Solution Approach 1:
The patent changes the plasma parameters specifically - using high electron density (1×10^9 to 1×10^12 cm^-3) combined with low electron temperature (<1 eV) - to achieve surface activation that enables bonding without requiring high pressure and temperature, thus avoiding material damage while maintaining strong adhesion
Solution Approach 2:
The patent replaces the mechanical/thermal bonding system (high pressure and temperature) with a plasma-based chemical activation system. The plasma treatment modifies surface chemistry to enable bonding at lower temperatures, substituting the need for high mechanical pressure and thermal energy
2Reliability
If conventional plasma treatment is used to activate bonding surfaces, then surface activation is achieved, but ion bombardment damages the bonding interface materials
Solution Approach 1:
The patent fundamentally changes plasma parameters by using high electron density (1×10^9 to 1×10^12 cm^-3) with low electron temperature (<1 eV), which reduces ion energy and minimizes ion bombardment damage while maintaining effective surface activation for bonding
Solution Approach 2:
The patent creates different conditions for different components of the plasma - electrons have high density for effective surface interaction while ions have low energy to avoid damage. This local differentiation of plasma component properties allows simultaneous surface activation and interface protection
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 reliable bonding at lower temperatures, reducing material damage and maintaining strong adhesion while minimizing ion bombardment and resistive species formation, thus enhancing the conductivity and reliability of the bond interface.
Implementation Method 1
exposing the first surface to a plasma having an electron density in a range between 1×10^9 cm−3 and 1×10^12 cm−3, and including a reducing agent; and bonding the first surface to the second surface
Implementation Method 2
the plasma is generated by a plasma generator using a slot-plane-antenna (SPA) technique
Implementation Method 3
After bonding the first surface to the second surface, annealing a bond interface between the first surface and the second surface
Data Source
AI summary
A method is provided for activating a first surface for bonding to a second surface. In some embodiments, the method includes exposing the first surface to a plasma that has a high electron density in a range between 1×109 cm−3 and 1×1012 cm−3 and a low electron temperature of less than 1 eV, and then bonding the first surface to the second surface. In some embodiments, the plasma is generated by a plasma generator using a slot-plane-antenna (SPA) technique. In some embodiments, the plasma also includes a reducing agent.