Bulk Acoustic Wave Resonator Shared Release Via

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Solution Overview

Problem

Existing bulk acoustic wave resonators face integration density issues due to the need for separate release vias to prevent electrical connection between adjacent bottom electrodes, which can lead to non-functional resonators.

Innovation Solution

Implementing a shared release via structure that spaces apart the bottom electrodes of adjacent resonators, ensuring they remain electrically isolated while sharing a common release channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate release vias are used to prevent electrical connection between adjacent bottom electrodes, then electrical isolation is achieved, but integration density deteriorates due to additional area occupation

Engineering Contradiction:
Improveelectrical isolationVSAvoidintegration density
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the release via structures of two adjacent resonators into a single shared release via. The bottom electrodes are designed with hollow gaps that align with a common release via, allowing both resonators to share the same via structure. This eliminates the need for separate release vias for each resonator, thereby improving integration density while maintaining electrical isolation through the hollow gap design.

Inventive Principle:
Principle #5Merging (Combining)

2Area of stationary object

If a shared release via is used to improve integration density, then area occupation is reduced, but electrical connection between adjacent bottom electrodes may occur

Engineering Contradiction:
Improveintegration densityVSAvoidelectrical isolation
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The bottom electrodes are segmented into hollow gap structures that create physical discontinuities at the locations where the shared release via passes through. This segmentation breaks the electrical continuity of the bottom electrodes, ensuring electrical isolation is maintained even though a shared release via is used. The hollow gaps act as insulating barriers that prevent electrical connection through the via.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If release channels are formed to connect acoustic mirror cavities to shared release via, then manufacturing is simplified, but bottom electrodes become electrically connected at the bottom

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidelectrical isolation
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The bottom electrodes are designed with localized hollow gap structures at specific positions where the release channels pass through. This local modification creates electrical isolation zones exactly where needed, while maintaining the overall continuity of the bottom electrodes in other regions. The hollow gaps are strategically placed to prevent electrical connection through the release channels while preserving the acoustic mirror cavity functionality.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4654474A1Bulk acoustic wave resonator assembly with hollow bottom electrodes insulated from each other
Publication Date: 2025.11.26 ROFS MICROSYST TIANJIN CO LTD
  • EP4654474A1 patent drawingFigure 1~3
  • EP4654474A1 patent drawingFigure 4~6
  • EP4654474A1 patent drawingFigure 7~11

AI summary

The present disclosure relates to a bulk acoustic wave resonator assembly and its manufacturing method, the assembly comprising: two adjacent bulk acoustic wave resonators disposed on a substrate, wherein bottom electrodes of the two adjacent bulk acoustic wave resonators each comprise a first bottom electrode and a second bottom electrode electrically connected to each other, and an acoustic mirror cavity is defined between the first bottom electrode and the second bottom electrode; and a shared release via, wherein the acoustic mirror cavities of the two adjacent bulk acoustic wave resonators communicate with the shared release via through respective release channels, wherein: in a cross-section which is parallel to a thickness direction of the assembly and passes through the shared release via and the release channel communicating with the shared release via, the bottom electrodes of the two adjacent bulk acoustic wave resonators are spaced apart from each other. The present disclosure also relates to a filter and an electronic device.