Fabrication of a 3.5-GHz Solidly Mounted Resonator by Using an AlScN Piezoelectric Thin Film
| Autor: | Yu-Chen Chang, Yu-Cheng Chen, Kuo-Sheng Kao, Chan-Yu Chung, Ying-Chung Chen |
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| Rok vydání: | 2021 |
| Předmět: |
Electromechanical coupling coefficient
Materials science Silicon business.industry chemistry.chemical_element Surfaces and Interfaces Substrate (electronics) SMR BAW Nitride Engineering (General). Civil engineering (General) Distributed Bragg reflector Surfaces Coatings and Films Resonator 3.5-GHz chemistry Sputtering Materials Chemistry Optoelectronics TA1-2040 Thin film business AlScN |
| Zdroj: | Coatings, Vol 11, Iss 1151, p 1151 (2021) Coatings Volume 11 Issue 10 |
| ISSN: | 2079-6412 |
| Popis: | In this study, a 3.5-GHz solidly mounted resonator (SMR) was developed by doping scandium in aluminum nitride to form AlScN as the piezoelectric thin film. Molybdenum (Mo) of 449 nm thickness and silicon dioxide (SiO2) of 371 nm thickness were used as the high and low acoustic impedance films, respectively, which were alternately stacked on a silicon substrate to form a Bragg reflector. Then, an alloy target with atomic ratio of 15% Sc was adopted to deposit the piezoelectric AlScN thin film on the Bragg reflector, using a radio frequency magnetron sputtering system. The characteristics of the c-axis orientation of the AlScN thin films were optimized by adjusting sputtering parameters as sputtering power of 250 W, sputtering pressure of 20 mTorr, nitrogen gas ratio of 20%, and substrate temperature of 300 °C. Finally, a metal top electrode was coated to form a resonator. The X-ray diffraction (XRD) analysis showed that the diffraction peak angles of the AlScN film shifted towards lower angles in each crystal phase, compared to those of AlN film. The energy dispersive X-ray spectrometer (EDX) analysis showed that the percentage of scandium atom in the film is about 4.5%, regardless of the sputtering conditions. The fabricated resonator exhibited a resonance frequency of 3.46 GHz, which was a small deviation from the preset resonance frequency of 3.5 GHz. The insertion loss of −10.92 dB and the electromechanical coupling coefficient of 2.24% were obtained. As compared to the AlN-based device, the AlScN-based resonator exhibited an improved electromechanical coupling coefficient by about two times. |
| Databáze: | OpenAIRE |
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