SAW Resonator Electrode Structure for Spurious Mode Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SAW resonators face challenges in miniaturization due to inadequate crystallinity and orientation of metal layers in IDT electrodes, leading to unwanted spurious modes and reduced reliability and power durability, especially when high-density metal layers are deposited without proper crystallinity and etched unevenly.
Innovation Solution
A SAW resonator with an improved electrode structure featuring a seed layer and an amorphous layer on a piezoelectric substrate, where the seed layer enhances lattice alignment and crystallinity of the main electrode layer, and an ohmic contact layer is included to maintain ohmic contact, along with an insulating layer to improve etching quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a high-density metal layer is deposited through sputtering to miniaturize the resonator, then acoustic velocity is reduced and miniaturization is achieved, but crystallinity and orientation of the metal layer deteriorate, causing uneven etching and spurious modes
Solution Approach 1:
A seed layer is introduced as an intermediary between the piezoelectric substrate and the main electrode layer. This seed layer has a crystal structure that matches the piezoelectric substrate, serving as a template that guides the formation of the main electrode layer with proper crystallinity and orientation, thereby resolving the contradiction between miniaturization and manufacturing precision
Solution Approach 2:
The invention changes the structural parameters of the electrode by introducing a multi-layer configuration with specific crystal orientations. The seed layer is designed with a crystal structure matching the piezoelectric substrate, which fundamentally alters the deposition and etching parameters of subsequent layers, enabling both miniaturization and high manufacturing precision
2Ease of manufacture
If the metal layer is deposited without proper crystallinity to simplify the process, then manufacturing complexity is reduced, but etching quality deteriorates and residual materials remain on the substrate
Solution Approach 1:
The seed layer is deposited in advance with a crystal structure matched to the piezoelectric substrate, creating a preparatory foundation that ensures subsequent metal layers will have proper crystallinity and orientation. This preliminary action with the seed layer simplifies the overall process by establishing a template that guides all subsequent deposition and etching operations
3Volume of moving object
If a multi-stacking structure is applied to miniaturize the resonator, then acoustic velocity is reduced, but the complexity of the electrode structure increases
Solution Approach 1:
The electrode structure is segmented into distinct functional layers: a seed layer for crystal template, a main electrode layer for electrical function, and an amorphous protective layer. This segmentation allows each layer to be optimized independently for its specific function, achieving miniaturization without excessive overall complexity
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 improved electrode structure enhances the crystallinity and orientation of metal layers, maintaining etching quality and enabling miniaturization while improving the performance and reliability of the SAW resonator by reducing unwanted spurious modes and contact loss.
Implementation Method 1
a seed layer stacked on the surface of the piezoelectric substrate... the seed layer enhances lattice alignment and crystallinity of the main electrode layer
Implementation Method 2
A surface acoustic wave device is an electromechanical device that utilizes the interaction between the surface acoustic wave and conduction electrons of a semiconductor, which uses surface acoustic waves transferred to the surface of a piezoelectric crystal
Data Source
AI summary
Provided are a SAW resonator having an electrode structure with improved performance and a method of manufacturing the same. The SAW resonator includes a piezoelectric substrate; and a plurality of IDT electrodes formed on the piezoelectric substrate, wherein each of the plurality of IDT electrodes includes: a seed layer stacked on a surface of the piezoelectric material; and a main electrode layer formed on the seed layer, and an amorphous layer is formed on a top surface of the piezoelectric substrate.