Elastic Wave Filter Electrode Layout With Low-Damage Piezoelectric Etching
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Solution Overview
Problem
Existing etching technologies for controlling the thickness of piezoelectric layers in elastic wave devices cause significant insertion loss due to the formation of thick damage layers, leading to poor frequency concentration and reduced electrical performance, especially in high-frequency filters.
Innovation Solution
The elastic wave device features a supporting substrate with a piezoelectric layer having a damage layer thickness less than 0.00075λ and interdigital transducers electrodes spaced less than 3 μm apart, utilizing ion beam etching to ensure thickness uniformity and minimize damage layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching technology is used to control piezoelectric layer thickness, then thickness control is achieved, but a thick damage layer is generated causing significant insertion loss
Solution Approach 1:
The patent changes the etching parameters by using ion beam etching with specific conditions (ion energy, etching time, gas flow rates) to achieve precise thickness control while minimizing damage layer formation. The damage layer thickness is controlled to be less than 0.00075λ through optimized etching parameters, resolving the contradiction between thickness precision and energy loss.
2Speed
If piezoelectric layer thickness is reduced for high frequency filter, then central frequency range is improved, but frequency shifts become more severe due to same error
Solution Approach 1:
The patent replaces conventional mechanical/chemical etching methods with ion beam etching technology. This substitution enables more precise control of piezoelectric layer thickness with reduced damage layer, thereby improving both the high-frequency response and the accuracy of the central frequency by minimizing thickness variations.
3Loss of energy
If damage layer thickness is reduced to minimize insertion loss, then electrical performance is improved, but manufacturing complexity increases
Solution Approach 1:
The ion beam etching process serves multiple functions simultaneously: it controls piezoelectric layer thickness, minimizes damage layer formation, and prepares the surface for subsequent electrode deposition. This multi-functionality reduces the need for separate processing steps, thereby managing manufacturing complexity while achieving low insertion loss.
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 reduces insertion loss, improves frequency concentration, and ensures electrical performance by controlling the thickness uniformity of the piezoelectric layer, thereby enhancing the quality of the filter.
Implementation Method 1
a piezoelectric layer (200), and a plurality of interdigital transducers electrodes (300)
Data Source
AI summary
The present application provides an elastic wave device, a manufacturing method thereof, and an electronic module. The elastic wave device includes a supporting substrate, a piezoelectric layer, and a plurality of interdigital transducers electrodes. The piezoelectric layer is formed on the supporting substrate. A surface of the piezoelectric layer away from the supporting substrate has a damage layer, and a thickness of the damage layer is less than 0.00075λ. The multiple interdigital transducers electrodes are spaced apart from each other and arranged on a side of the piezoelectric layer away from the supporting substrate. A distance between two adjacent interdigital transducers electrodes is less than 3 μm. λ is a wavelength of an elastic wave of the elastic wave device, and is determined based on an electrode period of the plurality of interdigital transducers electrodes.