5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications
Abstract Wireless local area network (WLAN) has gained widespread application as a convenient network access method, demanding higher network efficiency, stability, and responsiveness. High-performance filters are crucial components to meet these needs. Film bulk acoustic resonators (FBARs) are idea...
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| Format: | Article |
| Language: | English |
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Nature Publishing Group
2024-11-01
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| Series: | Microsystems & Nanoengineering |
| Online Access: | https://doi.org/10.1038/s41378-024-00820-3 |
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| author | Tingting Yang Chao Gao Yaxin Wang Binghui Lin Yupeng Zheng Yan Liu Cheng Lei Chengliang Sun Yao Cai |
| author_facet | Tingting Yang Chao Gao Yaxin Wang Binghui Lin Yupeng Zheng Yan Liu Cheng Lei Chengliang Sun Yao Cai |
| author_sort | Tingting Yang |
| collection | DOAJ |
| description | Abstract Wireless local area network (WLAN) has gained widespread application as a convenient network access method, demanding higher network efficiency, stability, and responsiveness. High-performance filters are crucial components to meet these needs. Film bulk acoustic resonators (FBARs) are ideal for constructing these filters due to their high-quality factor (Q) and low loss. In conventional air-gap type FBAR, aluminum nitride (AlN) is deposited on the sacrificial layer with poor crystallinity. Additionally, FBARs with single-crystal AlN have high internal stress and complicated fabrication process. These limit the development of FBARs to higher frequencies above 5 GHz. This paper presents the design and fabrication of FBARs and filters for WLAN applications, combining the high electromechanical coupling coefficient ( $${K}_{{\rm{t}}}^{2}$$ K t 2 ) of Al0.8Sc0.2N film with the advantages of the thin film transfer process. An AlN seed layer and 280 nm-thick Al0.8Sc0.2N are deposited on a Si substrate via physical vapor deposition (PVD), achieving a full width at half maximum (FWHM) of 2.1°. The ultra-thin film is then transferred to another Si substrate by wafer bonding, flipping, and Si removal. Integrating conventional manufacturing processes, an FBAR with a resonant frequency reaching 5.5 GHz is fabricated, demonstrating a large effective electromechanical coupling coefficient ( $${{k}}_{{\rm{eff}}}^{2}$$ k eff 2 ) of 13.8% and an excellent figure of merit (FOM) of 85. A lattice-type filter based on these FBARs is then developed for the Wi-Fi UNII-2 band, featuring a center frequency of 5.5 GHz and a −3 dB bandwidth of 306 MHz, supporting high data rates and large throughputs in WLAN applications. |
| format | Article |
| id | doaj-art-a80dc70968214a72bf53360b9c3eea58 |
| institution | OA Journals |
| issn | 2055-7434 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Nature Publishing Group |
| record_format | Article |
| series | Microsystems & Nanoengineering |
| spelling | doaj-art-a80dc70968214a72bf53360b9c3eea582025-08-20T02:08:16ZengNature Publishing GroupMicrosystems & Nanoengineering2055-74342024-11-011011910.1038/s41378-024-00820-35.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applicationsTingting Yang0Chao Gao1Yaxin Wang2Binghui Lin3Yupeng Zheng4Yan Liu5Cheng Lei6Chengliang Sun7Yao Cai8The Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityThe Institute of Technological Sciences, Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration, Wuhan UniversityAbstract Wireless local area network (WLAN) has gained widespread application as a convenient network access method, demanding higher network efficiency, stability, and responsiveness. High-performance filters are crucial components to meet these needs. Film bulk acoustic resonators (FBARs) are ideal for constructing these filters due to their high-quality factor (Q) and low loss. In conventional air-gap type FBAR, aluminum nitride (AlN) is deposited on the sacrificial layer with poor crystallinity. Additionally, FBARs with single-crystal AlN have high internal stress and complicated fabrication process. These limit the development of FBARs to higher frequencies above 5 GHz. This paper presents the design and fabrication of FBARs and filters for WLAN applications, combining the high electromechanical coupling coefficient ( $${K}_{{\rm{t}}}^{2}$$ K t 2 ) of Al0.8Sc0.2N film with the advantages of the thin film transfer process. An AlN seed layer and 280 nm-thick Al0.8Sc0.2N are deposited on a Si substrate via physical vapor deposition (PVD), achieving a full width at half maximum (FWHM) of 2.1°. The ultra-thin film is then transferred to another Si substrate by wafer bonding, flipping, and Si removal. Integrating conventional manufacturing processes, an FBAR with a resonant frequency reaching 5.5 GHz is fabricated, demonstrating a large effective electromechanical coupling coefficient ( $${{k}}_{{\rm{eff}}}^{2}$$ k eff 2 ) of 13.8% and an excellent figure of merit (FOM) of 85. A lattice-type filter based on these FBARs is then developed for the Wi-Fi UNII-2 band, featuring a center frequency of 5.5 GHz and a −3 dB bandwidth of 306 MHz, supporting high data rates and large throughputs in WLAN applications.https://doi.org/10.1038/s41378-024-00820-3 |
| spellingShingle | Tingting Yang Chao Gao Yaxin Wang Binghui Lin Yupeng Zheng Yan Liu Cheng Lei Chengliang Sun Yao Cai 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications Microsystems & Nanoengineering |
| title | 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications |
| title_full | 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications |
| title_fullStr | 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications |
| title_full_unstemmed | 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications |
| title_short | 5.5 GHz film bulk acoustic wave filters using thin film transfer process for WLAN applications |
| title_sort | 5 5 ghz film bulk acoustic wave filters using thin film transfer process for wlan applications |
| url | https://doi.org/10.1038/s41378-024-00820-3 |
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