Direct Wafer Bonding Without Plasma Surface Activation
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Solution Overview
Problem
Existing direct bonding methods for semiconductor elements, such as dies and wafers, often require plasma treatments that increase manufacturing costs, contaminate surfaces, and reduce bonding strength due to surface roughness and organic residue contamination, especially when using dicing frames.
Innovation Solution
A direct bonding method that avoids plasma exposure by slightly etching and terminating the bonding surfaces with species like hydrofluoric acid and tetramethylammonium hydroxide, followed by direct bonding without adhesives, and subsequent annealing to enhance bond strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma treatments are used for direct bonding, then bond strength can be improved, but manufacturing costs increase and surface contamination occurs
Solution Approach 1:
The patent removes the plasma treatment step from the bonding process, extracting the harmful and costly element while maintaining bonding effectiveness through alternative liquid-based surface preparation methods
Solution Approach 2:
The patent employs inexpensive liquid etchants and terminating agents that can be easily applied and removed, replacing expensive plasma equipment and processes with affordable chemical solutions
2Strength
If plasma treatments are used for direct bonding, then bond strength can be improved, but surface contamination increases
Solution Approach 1:
The patent extracts the plasma treatment step that causes surface contamination, replacing it with liquid chemical methods that do not introduce harmful contaminants to the bonding surfaces
Solution Approach 2:
The patent uses controlled liquid chemical environments that prevent oxidation and contamination of bonding surfaces, creating a clean bonding interface without the harmful effects of plasma exposure
3Reliability
If plasma treatments are used for direct bonding, then surface activation can be achieved, but process complexity and cost increase
Solution Approach 1:
The patent replaces the complex plasma physical system with simpler liquid chemical systems, substituting sophisticated equipment with straightforward chemical immersion processes
Solution Approach 2:
The patent changes the state of surface activation from plasma-based physical modification to liquid-based chemical modification, altering the fundamental parameter of surface treatment methodology to simplify the process
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 method reduces manufacturing costs, improves bonding strength, and maintains surface smoothness, enabling fine pitch connections between conductive and non-conductive features without plasma-induced defects.
Implementation Method 1
slightly etching the first bonding surface of the first element with a liquid etchant to activate the first bonding surface
Implementation Method 2
treating the first bonding surface with a terminating liquid treatment to terminate the first bonding surface with a terminating species
Implementation Method 3
directly bonding the first bonding surface to the second bonding surface such that the first and second nonconductive field regions are directly bonded to one another without an intervening adhesive
Implementation Method 4
subsequent annealing for enhanced strength
Data Source
AI summary
Disclosed herein are methods for direct bonding. In some embodiments, the direct bonding method includes providing a first element having a first bonding surface, providing a second element having a second bonding surface, slightly etching the first bonding surface, treating the first bonding surface with a terminating liquid treatment to terminate the first bonding surface with a terminating species, and directly bonding the first bonding surface to the second bonding surface without the use of an intervening adhesive and without exposing the first bonding surface to plasma.