Surface Acoustic Wave Structure With Embedded IDTs for Lower Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surface acoustic wave (SAW) devices face durability issues as transmitting power increases, particularly at higher operating frequencies and wider channel bandwidths, with existing ScAlN structures not adequately addressing these challenges.
Innovation Solution
A SAW device design featuring a piezoelectric layer coupled with a high acoustic velocity layer, where interdigital transducers are positioned within or near the surface of the high acoustic velocity layer, reducing von Mises stress and enhancing durability through specific layer thicknesses and materials like scandium-doped aluminum nitride and diamond, and using metallic layers for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmitting power is increased to support higher frequency and wider channel bandwidth, then communication system performance is improved, but device durability deteriorates
Solution Approach 1:
The device is segmented into multiple functional layers: a piezoelectric layer for electromechanical coupling and a separate high acoustic velocity layer for stress management. This segmentation allows each layer to be optimized independently - the piezoelectric layer for performance and the high acoustic velocity layer for durability under high power conditions.
Solution Approach 2:
The invention uses a composite structure combining piezoelectric materials with high acoustic velocity materials. This composite approach enables the device to simultaneously achieve high communication performance through piezoelectric coupling and high durability through the stress-resistant properties of the high acoustic velocity layer.
2Productivity
If operating frequency is increased to meet 5G requirements, then system capacity is improved, but device durability deteriorates
Solution Approach 1:
The device structure separates the high-frequency generation function (piezoelectric layer) from the stress-management function (high acoustic velocity layer). This allows the piezoelectric layer to operate at high frequencies for improved system capacity while the high acoustic velocity layer protects against durability degradation.
Solution Approach 2:
The invention changes the acoustic velocity parameter by introducing a high acoustic velocity layer, which modifies the stress distribution characteristics and enables high-frequency operation without compromising durability.
3Productivity
If wider channel bandwidth is implemented to increase data rate, then communication performance is improved, but device durability deteriorates
Solution Approach 1:
The segmented structure allows the piezoelectric layer to support wider bandwidth operations while the high acoustic velocity layer independently manages the mechanical stress, enabling high data rates without durability loss.
4Productivity
If ScAlN structures are used to achieve high piezoelectricity and thermal conductivity, then electromechanical coupling is improved, but stress management is inadequate
Solution Approach 1:
The invention segments the device into a piezoelectric layer (ScAlN) for electromechanical coupling and a separate high acoustic velocity layer for stress management. This resolves the inadequacy of ScAlN structures by adding a dedicated layer for stress management while preserving the high electromechanical coupling properties.
Solution Approach 2:
The high acoustic velocity layer acts as an intermediary between the piezoelectric layer and the substrate, managing stress transmission and protecting the piezoelectric layer from mechanical degradation while allowing the piezoelectric layer to maintain high coupling efficiency.
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
The design achieves reduced von Mises stress and increased durability, allowing for higher power handling and longer device lifespan by optimizing stress distribution and electromechanical coupling, thereby supporting higher operating frequencies and wider channel bandwidths.
Implementation Method 1
a piezoelectric layer; and a high acoustic velocity layer coupled to the piezoelectric layer
Implementation Method 2
the at least one transducer being configured to propagate a surface acoustic wave having an operating wavelength (λ) along the piezoelectric layer
Data Source
AI summary
The embodiments herein relate to surface acoustic wave (SAW) devices, such as filters and duplexers. The surface acoustic wave device includes piezoelectric layer and a high acoustic velocity layer coupled to the piezoelectric layer at a first surface of the high acoustic velocity layer. At least one transducer is provided within the high acoustic velocity layer and flush with or near the first surface. The at least one transducer is configured to propagate a surface acoustic wave having an operating wavelength along the piezoelectric layer.