Direct-Bonded Semiconductor Membranes on Piezoelectric Substrates
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Solution Overview
Problem
Conventional piezoelectric transducers require intermediate bonding layers that can attenuate strain transfer and are incompatible with biological environments, limiting their applications.
Innovation Solution
Direct bonding of semiconductor membranes to ultra-smooth piezoelectric substrates without the use of bonding agents, enabling strong adhesion and flat membrane integration suitable for microelectronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If intermediate bonding layers are used to bond semiconductor film to piezoelectric substrate, then bonding strength is improved, but strain transfer is attenuated and acoustic amplitude is reduced
Solution Approach 1:
The patent removes the intermediate bonding layer from the structure, achieving direct bonding between the piezoelectric substrate and semiconductor membrane. This extraction of the harmful intermediate layer eliminates the strain transfer attenuation and acoustic amplitude reduction while maintaining bonding strength through direct contact and surface roughness control.
2Ease of manufacture
If intermediate bonding layers are used to bond semiconductor film to piezoelectric substrate, then bonding is achieved, but compatibility with biological environments is reduced
Solution Approach 1:
The patent eliminates intermediate bonding layers that are incompatible with biological environments, achieving direct bonding between biocompatible materials. This allows the transducer to be used in biological applications such as ultrasound imaging and therapy without the harmful effects of polymer adhesives, metal layers, or glass bonding agents.
3Reliability
If semiconductor membrane thickness is reduced to 5 μm or less, then strain transfer efficiency is improved, but manufacturing precision requirements are increased
Solution Approach 1:
The patent specifies a thickness parameter of 5 μm or less for the semiconductor membrane to optimize strain transfer efficiency. This parameter change enables effective strain coupling from the piezoelectric substrate while remaining achievable with standard semiconductor fabrication processes.
4Manufacturing precision
If piezoelectric substrate surface roughness is reduced to 100 nm RMS or less, then direct bonding quality is improved, but manufacturing complexity is increased
Solution Approach 1:
The patent specifies a surface roughness parameter of 100 nm RMS or less for the piezoelectric substrate to enable high-quality direct bonding. This parameter change ensures proper adhesion and strain transfer while being achievable through standard polishing and etching processes.
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 enhances strain transfer and compatibility with biological environments, allowing for the development of piezoelectric transducers suitable for various devices such as sensors and optoelectronics, while maintaining the integrity of semiconductor and piezoelectric materials.
Implementation Method 1
a piezoelectric substrate having a membrane-bonding surface with a surface roughness of no greater than 100 nm RMS; a semiconductor membrane having a thickness of 5 μm or less bonded directly to the membrane-bonding surface; and a set of electrodes in electrical communication with the piezoelectric substrate and configured to apply an electric signal to the piezoelectric substrate
Data Source
AI summary
Piezoelectrically actuated devices constructed from thin semiconductor membranes bonded directly to piezoelectric substrates are provided. Methods for fabricating these devices are also provided. The bonding of the semiconductor to the piezoelectric material does not require the use of any intermediate layers, such as bonding agents.