Piezoelectric Layer Transfer With Low-Temperature Dielectric Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing piezoelectric structures for radiofrequency devices face issues such as significant deformation due to thermal expansion coefficient differences between piezoelectric and support substrates, leading to poor adhesion, curvature, and mechanical instability during thinning and packaging steps.
Innovation Solution
A low-temperature dielectric bonding layer is used to ensure mechanical stability during thinning and packaging, with molecular bonding and low-pressure assembly, followed by etching and polishing to achieve a rough surface for RF wave reflection, and a weakening zone for controlled separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a piezoelectric layer is grown directly on a substrate in a CMOS clean room, then manufacturing integration is improved, but contamination of the piezoelectric layer occurs due to particulates and chemicals in the clean room environment
Solution Approach 1:
The patent introduces an intermediary transfer process where the piezoelectric layer is grown on a separate handle wafer in a dedicated epitaxial workshop, then transferred to the CMOS substrate in a clean room. This intermediary handle wafer acts as a mediator that protects the piezoelectric layer from clean room contamination while enabling integration with CMOS substrates.
Solution Approach 2:
The manufacturing process is segmented into two distinct parts: piezoelectric layer growth in a dedicated epitaxial workshop on a handle wafer, and subsequent transfer to the CMOS substrate in a clean room. This segmentation allows each process to occur in its optimal environment without contamination risks.
2Object-affected harmful factors
If transfer of the piezoelectric layer is implemented, then contamination is prevented, but device complexity increases due to additional transfer steps
Solution Approach 1:
The handle wafer serves as an intermediary carrier that simplifies the transfer process. By growing the piezoelectric layer on this dedicated substrate first, the transfer to the final CMOS substrate becomes a controlled, single-step process using standard semiconductor techniques, rather than attempting direct growth on the final substrate.
3Device complexity
If direct growth on substrate is used, then process complexity is reduced, but manufacturing precision deteriorates due to contamination affecting layer quality
Solution Approach 1:
The process is divided into a high-precision growth stage in a controlled epitaxial environment and a separate transfer stage in the clean room. This segmentation ensures that the sensitive piezoelectric layer growth occurs without contamination risks, while the transfer process uses established semiconductor manufacturing techniques to maintain precision.
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 provides stable mechanical strength and reduces deformation, enabling efficient transfer and integration of piezoelectric layers with improved adhesion and reduced defects, suitable for microelectronics applications.
Implementation Method 1
a low-temperature dielectric bonding layer is deposited on a single face of the piezoelectric material substrate before the assembly step; The low-temperature dielectric bonding layer ensures sufficient mechanical stability
Implementation Method 2
the surface of the piezoelectric layer located at the interface with the intermediate bonding layer is sufficiently rough to allow reflection of parasitic waves in all directions
Implementation Method 3
the dielectric bonding layer comprises a silicon oxide layer deposited on the piezoelectric material substrate by plasma-enhanced chemical vapor deposition
Implementation Method 4
forming a weakening zone in the layer of piezoelectric material so as to delimit the piezoelectric layer to be transferred; fracturing and separating the piezoelectric structure along the weakening zone
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A process for manufacturing a piezoelectric structure (10, 10'), said process being characterized in that it comprises providing a substrate of piezoelectric material (20), providing a carrier substrate (100), depositing a dielectric bonding layer (1001) at a temperature lower than or equal to 300°C on a single side of the substrate of piezoelectric material (20), a step (1') of joining the substrate of piezoelectric material (20) to the carrier substrate (100) via the dielectric bonding layer (1001), a thinning step (2') for forming the piezoelectric structure (10, 10'), which comprises a layer of piezoelectric material (200) joined to a carrier substrate (100).