Composite Piezoelectric Substrate via Ion Implantation Separation
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Solution Overview
Problem
Current methods for manufacturing composite piezoelectric substrates face challenges such as limited material options for oriented films, inefficient material utilization, difficulty in controlling film thickness, weak bonding leading to microcavities and piezoelectric degradation, and high-temperature processing requirements.
Innovation Solution
A method involving ion implantation to form a defective layer, followed by cleaning activation and bonding with a supporting substrate, and subsequent separation to create a composite piezoelectric substrate with a separation layer, which allows for efficient reuse of piezoelectric material and eliminates the need for high-temperature hydrogen removal, thereby preventing microcavity formation and maintaining piezoelectricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bonding is performed through hydrophilic groups, then bonding strength is improved, but microcavities form and piezoelectricity degrades
Solution Approach 1:
The patent applies preliminary action by performing ion implantation to create a defective layer before bonding occurs. This defective layer acts as a pre-prepared separation plane that allows for controlled separation after bonding, preventing the formation of microcavities at the bonding interface while maintaining strong bonding strength. The defective layer is created at a specific depth below the surface, ensuring that bonding proceeds normally first, then separation can occur cleanly along this pre-defined path.
Solution Approach 2:
The patent applies segmentation by dividing the piezoelectric substrate into two distinct parts: a surface separation layer that remains bonded to the supporting substrate, and a deeper defective layer that serves as the separation plane. This segmentation allows the bonding interface to remain intact for strong adhesion while providing a separate, controlled path for future separation that prevents microcavity formation.
2Length of moving object
If polishing is used to thin the piezoelectric substrate, then film thickness is reduced, but material utilization efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-forming a defective layer at a specific depth below the surface before any separation occurs. This defective layer serves as a predetermined separation plane, allowing the piezoelectric material to be separated cleanly at the desired thickness without requiring excessive polishing. The separation layer thickness is controlled by the depth of defective layer formation rather than by removing large amounts of material through polishing.
Solution Approach 2:
The patent applies discarding and recovering by selectively separating only the necessary portion of the piezoelectric substrate (the separation layer) while preserving and reusing the remaining piezoelectric substrate. The defective layer enables clean separation at the desired thickness, allowing the bulk piezoelectric material to be recovered and reused for additional separation layers, dramatically improving material utilization efficiency compared to traditional polishing methods that discard most of the substrate.
3Productivity
If high-speed heating is applied to break the piezoelectric substrate, then separation speed is improved, but crystal structure breaks and piezoelectricity degrades
Solution Approach 1:
The patent applies preliminary action by pre-forming a defective layer with modified physical properties at a specific depth before separation is needed. This defective layer, created through ion implantation, has different thermal and mechanical properties than the surrounding crystal. When heating is applied, the defective layer responds differently, enabling separation to occur preferentially at this pre-defined location rather than requiring extreme heating that would damage the crystal structure.
Solution Approach 2:
The patent uses the defective layer as an intermediary that mediates the separation process. Instead of directly applying high-speed heating to break the crystal, the defective layer acts as an intermediate structure that facilitates separation at lower, safer temperatures. The ion-implanted defective layer creates a plane of weakness that guides the separation process, allowing productivity improvement without compromising crystal integrity.
4Productivity
If deposition method is used to form piezoelectric film, then film formation speed is improved, but material selection is limited
Solution Approach 1:
The patent applies inversion by reversing the conventional approach. Instead of depositing piezoelectric material onto a substrate (which limits material selection to deposition-compatible materials), the patent starts with bulk piezoelectric single crystal substrates and separates thin films from them. This inversion allows use of any piezoelectric material that can be grown as a single crystal, greatly expanding material selection while maintaining high productivity through the separation 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 enables the formation of ultrathin piezoelectric films with uniform thickness, reducing material waste and maintaining high piezoelectricity, suitable for applications in acoustic wave devices with improved thermal conductivity and reduced material costs.
Implementation Method 1
a second step of implanting ions from a surface of the piezoelectric substrate to form a defective layer in a region having a predetermined depth from the surface of the piezoelectric substrate
Implementation Method 2
a cleaning activation step of removing impurities adhering to at least one of the surface of the piezoelectric substrate in which the defective layer is formed and a surface of the supporting substrate to directly expose the constituent atoms of the surface and activate it
Implementation Method 3
a fourth step of separating the substrate bonded body at the defective layer formed in the piezoelectric substrate so that a separation layer between the surface of the piezoelectric substrate and the defective layer is separated from the piezoelectric substrate and bonded to the supporting substrate
Implementation Method 4
a fifth step of smoothing the surface of the separation layer of the composite piezoelectric substrate
Data Source
Figure 1(a-1)~1(f-2)
Figure 2(a)~2(f)
Figure 3(a)~3(f)
AI summary
The present invention provides a method for manufacturing a composite piezoelectric substrate capable of forming an ultrathin piezoelectric film having a uniform thickness by efficiently using a piezoelectric material. a) A piezoelectric substrate (2) and a supporting substrate (10) are prepared, b) ions are implanted from a surface (2a) of the piezoelectric substrate (2) to form a defective layer (4) in a region having a predetermined depth from the surface (2a) of the piezoelectric substrate (2), c) impurities adhering to at least one of the surface (2a) of the piezoelectric substrate (2) in which the defective layer (4) is formed and a surface (10a) of the supporting substrate (1) are removed to directly expose the constituent atoms of the surfaces (2a and 10a) and activate them, d) the supporting substrate (10) is bonded to the surface (2a) of the piezoelectric substrate (2) to form a substrate bonded body (40), e) the substrate bonded body (40) is separated at the defective layer (4) formed in the piezoelectric substrate (2) so that a separation layer (3) between the surface (2a) of the piezoelectric substrate (2) and the defective layer (4) is separated from the piezoelectric substrate (2) and bonded to the supporting substrate (10) to form a composite piezoelectric substrate (30), and f) the surface (3a) of the separation layer (3) of the composite piezoelectric substrate (30) is smoothed.