Study on the High Power-Durable Thin-Film Electrodes for Surface Acoustic Wave Devices.
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Accession number;99A0938073
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| Title;Study on the High Power-Durable Thin-Film Electrodes for Surface Acoustic Wave Devices. |
| Author;
KIMURA NORITOSHI
(Tohoku Univ.)
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Journal Title;Record of Electrical and Communication Engineering Conversazione, Tohoku University
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Journal Code:F0511A
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ISSN:0385-7719
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VOL.68;NO.1;PAGE.32-35(1999)
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| Figure&Table&Reference;FIG.10, REF.8 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Surface acoustic wave(SAW) devices are widely used in RF circuits of portable and cellular phones as interstage filters and antenna duplexers. The SAW devices used at RF-range require narrow and thin electrodes. Thus, it had been difficult to ensure the power-durability of Al electrodes. This paper shows new power-durable thin-film electrodes for RF SAW devices. First, the power durability of double-mode SAW(DMS) filters, which were used as a power durability test device to evaluate new film electrodes, was investigated. Al-Cu alloy electrodes, which have been widely used as power-durable electrodes, were improved in power durability by Cu atom segregation to the grain boundary using a heat treatment. It is found that the power durability of Al-0.5wt%Cu alloy electrodes was improved by about three times after heated at 200.DEG.C. for 5-24 hours. Next, the power durability of new Al-M (M: refractory metal such as Ta and W) alloy electrodes have been evaluated. It was shown that the power durability of Al-W alloy electrodes became approximately five times greater than that of Al-Ti alloy electrodes which have been known as high power-durable electrodes. However, the addition of M increased the insertion loss(IL) of DMS filters due to the increase in their film resistivity. To realize both low-loss and high power-durable electrodes, single-crystal Al films were successfully grown on 64.DEG.Y-X LiNbO3 substates using a Ti buffer-layer (Al/Ti film structure). The Ti films as buffer-layer grown on 64.DEG.Y-X LiNbO3 substrates and the Al films grown on the Ti(001) were recognized as single-crystal Ti(001) and Al(110), respectively. It was revealed that the IL of the single-crystal Al/Ti electrodes in the DMS filters was superior to that of polycrystalline Al, Al-Cu alloy and Al-W alloy electrodes.... (author abst.) |
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