Piezoelectric Substrate Bonding via Neutralized Beam Activation
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Solution Overview
Problem
The existing methods for bonding a silicon substrate to a piezoelectric substrate, such as the plasma activation method, face challenges with low bonding strength at ambient temperature and the risk of cracking due to thermal expansion differences, while the Fast Atom Beam method results in low bonding strength leading to separation during processing.
Innovation Solution
A method involving the formation of a bonding layer with materials like silicon nitride, aluminum nitride, or tantalum pentoxide on the substrates, followed by irradiation with a neutralized beam to activate the surfaces for direct bonding at ambient temperature, enhancing the bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma activation method is used for bonding silicon substrate to piezoelectric substrate, then bonding can be achieved, but bonding strength is low at ambient temperature and cracks occur due to thermal expansion differences when heating is applied
Solution Approach 1:
The invention changes the bonding interface material properties by forming a silicon oxide film with specific characteristics (amorphous or crystalline structure, controlled thickness of 1-10 μm) that can accommodate thermal expansion differences between silicon and piezoelectric substrates, thereby preventing cracks while maintaining strong bonding after heating
Solution Approach 2:
The silicon oxide film acts as an intermediary layer between the silicon substrate and piezoelectric substrate, mediating the thermal expansion mismatch and enabling reliable bonding that withstands heating processes without cracking
2Temperature
If Fast Atom Beam method is used for direct bonding, then bonding can be performed at ambient temperature, but bonding strength is low causing separation during subsequent processing
Solution Approach 1:
The silicon oxide film serves as a mediator that enables strong bonding between silicon and piezoelectric substrates at ambient temperature through the Fast Atom Beam method, eliminating the need for high-temperature processing while achieving sufficient bonding strength to prevent separation during subsequent steps
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 allows for strong and reliable bonding of piezoelectric and single-crystal substrates at ambient temperature, preventing cracking and separation during subsequent processing steps.
Implementation Method 1
irradiating a neutralized beam onto a surface of the bonding layer and a surface of the supporting body to activate the surface of the bonding layer and the surface of the supporting body
Data Source
AI summary
A bonding layer 3 is formed over a piezoelectric material substrate, and the bonding layer is made of one or more materials selected from the group consisting of silicon nitride, aluminum nitride, alumina, tantalum pentoxide, mullite, niobium pentoxide and titanium oxide. A neutralized beam is irradiated onto a surface of the bonding layer and a surface of a supporting body to activate the surface of the bonding layer and the surface of the supporting body. The surface of the bonding layer and the surface of the supporting body are bonded by direct bonding.