Polycrystalline Substrate Orientation for High-Q SAW Filters
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Solution Overview
Problem
Existing elastic wave filters, such as surface acoustic wave (SAW) filter devices, face challenges in achieving high Q-factor performance due to limitations in the design of piezoelectric layers and interdigital transducers (IDT) electrodes.
Innovation Solution
A substrate with a specific crystallographic orientation ratio, comprising a polycrystalline material with a main support surface containing 7% to 20% (101)-oriented crystal grains in a 150 μm×150 μm observation region, enhances the Q-factor by providing improved flexural strength and bonding stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piezoelectric layer or IDT electrode designs are used, then device structure is simple, but Q-factor performance is insufficient
Solution Approach 1:
The patent changes the crystallographic orientation parameters of the polycrystalline substrate by controlling the proportion of (101)-oriented crystal grains to 7%-20%, which fundamentally alters the substrate's elastic properties and enables high Q-factor performance without modifying the piezoelectric layer or IDT electrode designs
Solution Approach 2:
The patent uses a polycrystalline material with specific multi-orientation crystal grains ((101), (001), and (111) orientations) to create a composite substrate structure that combines the benefits of different crystal orientations, achieving both high Q-factor and sufficient mechanical strength
2Reliability
If substrate flexural strength is increased to prevent chipping, then bonding reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent changes the mechanical properties of the substrate by controlling the crystal grain orientation distribution, specifically achieving 7%-20% (101)-oriented grains which provide optimal balance between flexural strength and manufacturability, preventing chipping during bonding without requiring complex manufacturing processes
3Reliability
If piezoelectric layer or IDT electrode design is optimized, then Q-factor improves, but device complexity increases
Solution Approach 1:
The patent extracts the Q-factor optimization function from the piezoelectric layer and IDT electrode design and transfers it to the substrate itself by controlling the substrate's crystal grain orientation, thereby simplifying the overall device structure while maintaining high Q-factor performance
Solution Approach 2:
The substrate acts as an intermediary that mediates between the piezoelectric layer/IDT electrodes and the underlying support structure, with its specific crystal grain orientation (7%-20% (101)-oriented grains) enabling it to enhance Q-factor performance without requiring modifications to the piezoelectric layer or IDT electrode designs
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 substrate design achieves enhanced Q-factor performance, preventing chipping during bonding processes and ensuring production quality and efficiency, while also improving the Q-value of electronic devices.
Implementation Method 1
a piezoelectric layer provided on the main support surface of the carrier substrate
Implementation Method 2
In existing elastic wave filters, such as surface acoustic wave (SAW) filter devices
Data Source
AI summary
A substrate, an electronic device, and a module are provided. The substrate provided by embodiments includes a carrier substrate formed from a polycrystalline material having a main support surface, where an observation region on the main support surface or on any transverse interface parallel to the main support surface contains (101)-oriented crystal grains, and a proportion of the (101)-oriented crystal grains in the observation region is 7% to 20% of a total number of grains in the observation region, and where the observation region measures 150 μm×150 μm.