SAW Resonator Temperature Compensation Layer for Frequency Stability
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Solution Overview
Problem
Existing surface acoustic wave (SAW) filters face challenges in improving the resonant temperature coefficient of frequency, particularly in achieving high quality factor, low loss, and small temperature drift.
Innovation Solution
A surface acoustic wave resonator device is designed with a piezoelectric substrate, an interdigital transducer, and a first temperature compensation layer. The temperature compensation layer includes a body part and a protruding part, which increases the contact area with the piezoelectric substrate, thereby enhancing the temperature coefficient of frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional temperature compensation layer is used in SAW filters, then the structure is simple, but the resonant temperature coefficient of frequency cannot be effectively improved
Solution Approach 1:
The temperature compensation layer is extended in the thickness direction to form a protruding part that contacts the piezoelectric substrate, transforming a planar structure into a three-dimensional structure. This dimensional change increases the contact area between the temperature compensation layer and the piezoelectric substrate, thereby improving the resonant temperature coefficient of frequency while maintaining structural feasibility
Solution Approach 2:
The temperature compensation layer is divided into a body part and a protruding part with distinct functions. The body part covers the interdigital transducer, while the protruding part extends toward the piezoelectric substrate to enhance thermal contact. This segmentation allows each part to optimize its function, improving overall temperature compensation effectiveness
2Manufacturing precision
If the contact area between temperature compensation layer and piezoelectric substrate is increased, then the temperature coefficient of frequency is improved, but the device structure becomes more complex
Solution Approach 1:
Instead of increasing contact area in the planar direction, the temperature compensation layer is extended in the thickness direction to form a protruding part. This approach achieves increased contact area with the piezoelectric substrate while avoiding complex lateral extensions, thus improving temperature coefficient of frequency with controlled structural complexity
3Manufacturing precision
If the protruding part of temperature compensation layer contacts the piezoelectric substrate, then the temperature compensation effect is enhanced, but the acoustic-electrical energy conversion may be affected
Solution Approach 1:
The piezoelectric substrate is divided into different regions with different heights: a first piezoelectric part under the interdigital transducer maintains original height for optimal acoustic-electrical conversion, while a third piezoelectric part under the protruding part is removed to allow temperature compensation contact. This local differentiation ensures that energy conversion and temperature compensation functions do not interfere with each other
Solution Approach 2:
The protruding part of the temperature compensation layer acts as an intermediary structure that bridges the temperature compensation function and the piezoelectric substrate without directly interfering with the interdigital transducer's acoustic-electrical conversion. It provides thermal contact while being spatially separated from the active transducer region
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 proposed solution improves the temperature coefficient of frequency of the resonator device and the filter, while ensuring the stability and reliability of acoustic-electrical energy conversion between the interdigital transducer and the piezoelectric substrate.
Implementation Method 1
a piezoelectric substrate; an interdigital transducer, disposed on the piezoelectric substrate
Implementation Method 2
a first temperature compensation layer, disposed on the piezoelectric substrate and including a body part and a protruding part, wherein the body part covers a sidewall of the interdigital transducer and a surface of the interdigital transducer at a side away from the piezoelectric substrate
Data Source
AI summary
A surface acoustic wave resonator device and method for manufacturing the same and filter, the surface acoustic wave resonator device includes: a piezoelectric substrate; an interdigital transducer, disposed on the piezoelectric substrate and comprising a first interdigital electrode structure and a second interdigital electrode structure, wherein each interdigital electrode structure comprises an interdigital electrode and an interdigital electrode lead-out part connected with each other; and a first temperature compensation layer, disposed on the piezoelectric substrate and comprising a body part and a protruding part, wherein the body part covers the interdigital transducer, the protruding part is protruded from the body part towards the piezoelectric substrate in a third direction perpendicular to a main surface of the piezoelectric substrate, and is surrounded by the piezoelectric substrate in a direction parallel to the main surface of the piezoelectric substrate.