Piezoelectric Composite Substrate Ion Implantation Bonding
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Solution Overview
Problem
Conventional methods for producing piezoelectric composite substrates face challenges in controlling the inclination of crystal and polar axes, leading to poor productivity and adverse effects such as pyroelectricity, which damages the bonding surface and reduces piezoelectricity.
Innovation Solution
A method involving ion-implantation, bonding, and separation steps is used, where ions are implanted into a polar surface of a first piezoelectric single crystal material to form microcavities, allowing for controlled bonding with a second piezoelectric single crystal material, thereby setting the crystal axis direction and eliminating pyroelectricity by canceling polarities on the bonding surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sputtering or CVD is used to produce single-crystal thin film, then the thin film has c-axis orientation with vertically aligned crystal axis, but the performance of piezoelectric element cannot be adjusted by controlling the inclination of crystal axis and polar axis
Solution Approach 1:
The invention performs preliminary actions by bonding piezoelectric single crystal materials to a substrate before thin film deposition, and by implanting ions to create microcavities in advance. This preliminary structuring enables subsequent control of crystal axis inclination and polar axis orientation during the deposition process, allowing performance adjustment without sacrificing manufacturing precision
2Manufacturing precision
If polishing of single-crystal material base is performed to control crystal axis and polar axis inclination, then the inclination can be controlled, but most of the piezoelectric material is discarded as shavings resulting in poor efficiency of utilization
Solution Approach 1:
The invention applies the discarding and recovering principle by using a substrate that can be reused after the thin film is deposited and processed. The substrate serves multiple cycles, and only the necessary thin film material is consumed, dramatically reducing piezoelectric material waste compared to polishing methods where bulk material is discarded
Solution Approach 2:
The substrate is prepared in advance with specific surface properties and crystal orientation before deposition, eliminating the need for post-deposition polishing that would waste material. The preliminary preparation enables direct control of crystal axis inclination during deposition
3Ease of manufacture
If heating is performed after piezoelectric materials are held and stacked to thermally bond them, then bonding is achieved, but the piezoelectric material in thin film form is liable to be broken and difficult to handle causing poor productivity
Solution Approach 1:
The invention performs preliminary bonding of the piezoelectric single crystal material to the substrate before thin film deposition and processing. This preliminary bonding creates a stable structure that prevents thin film breakage during subsequent handling and processing steps, improving productivity without compromising bonding quality
Solution Approach 2:
The bonding process is applied locally at specific regions where piezoelectric materials need to be joined, rather than requiring extensive heating of entire thin film structures. This localized approach reduces thermal stress and prevents breakage
4Ease of manufacture
If piezoelectric materials are heated to locally develop pyroelectric charges on bonding surface, then bonding may be enhanced, but the bonding surface is damaged and piezoelectricity is reduced
Solution Approach 1:
The invention converts the potentially harmful pyroelectric effect into a beneficial bonding mechanism. By controlling the heating process and material composition, the pyroelectric charges that would normally damage the bonding surface are instead used to enhance bonding strength and electrical contact, turning a harmful factor into an advantage
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 improves productivity by allowing controlled crystal axis and polar axis orientation, reduces pyroelectric charges, and enhances the quality of the bonding surface, enabling the reuse of piezoelectric materials and stable piezoelectric performance.
Implementation Method 1
In an ion-implantation step, ions are implanted into a first polar surface of the first piezoelectric single crystal material to form localized microcavities in a separation layer
Implementation Method 2
In a separation step, after the bonding step, the microcavities are subjected to thermal stress to divide the separation layer
Implementation Method 3
the first polar surface of the first piezoelectric single crystal material is bonded to a second polar surface of the second piezoelectric single crystal material
Data Source
AI summary
A method for producing a piezoelectric composite substrate with satisfactory productivity controls the inclination of the crystal axis and the polar axis of a single-crystal thin film and prevents an adverse effect due to pyroelectricity in a production process. The method for producing a piezoelectric composite substrate provided with a plurality of piezoelectric materials includes an ion-implantation step, a bonding step, and a separation step. In the ion-implantation step, H+ ions are implanted into a piezoelectric single crystal material. In the bonding step, the piezoelectric single crystal material is bonded to a piezoelectric single crystal material. At this time, the polarity of the polar surface of the piezoelectric single crystal material is opposite to the polarity of the polar surface of the piezoelectric single crystal material, the polar surfaces being bonded to each other. In the separation step, a separation layer of the piezoelectric single crystal material is divided by heating to separate a piezoelectric single-crystal thin film.