High power durable SAW filter with epitaxial aluminium electrodes on 38.5/spl deg/ rotated Y-X LiTaO/sub 3/ by two-step process sequence in titanium intermediate layer

Nakagawara, Osamu; Saeki, M.; Teramoto, Akinobu; Hasegawa, Masato; Ieki, Hideharu

doi:10.1109/ultsym.2003.1293246

Cited by 12 publications

(11 citation statements)

References 2 publications

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“…To limit damage, MURATA has developed a specific process for the metal deposition. 17 Finally, another problem is the temperature drift. It is not as critical as the previous problems, but it can give a drift of the electrical characteristics of the filter.…”

Section: Surface Acoustic Wave Filtersmentioning

confidence: 99%

Piezoelectric materials and their applications in radio frequency domain and telecommunications

Benech

Duchamp

2015

Advances in Applied Ceramics

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The market of telecommunications has grown rapidly this last decade. The main parameter regarding users is the data rate. It must be increased with each new standard. To reach this goal, the constraints on electronics circuits and devices for radio frequency front end had increased drastically, particularly to obtain high quality radio frequency filters. In this context, piezoelectric materials and devices offer the only way to get radio frequency filters with low insertion losses and high out of band rejection at the same time. A lot of works were performed by several research teams in the world, devoted to materials, to technological steps and to devices. Among piezoelectric materials, some of them are candidates for telecommunications applications. After a review of the main piezoelectric materials, the desired characteristics have been analysed, and finally, few materials are retained. The trends in functionality terms and consequently of required materials for filters are presented for future generations.

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Section: Surface Acoustic Wave Filtersmentioning

confidence: 99%

Piezoelectric materials and their applications in radio frequency domain and telecommunications

Benech

Duchamp

2015

Advances in Applied Ceramics

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“…The improvement of various characteristics of SAW/BAW filters, such as loss, temperature stability, power durability, and downsizing have been highly sought and many researchers have engaged in the enhancement of those characteristics. [1][2][3][4][5][6][7][8][9][10] Alternatively, multiplexer configurations, in which multiple filters are directly connected to an antenna tend to be used actively in RFFE modules to reduce the number of antennae and to realize simultaneous data transmission/reception using multifrequency bands such as carrier aggregation. 11) For this usage, the out-band rejection characteristics of SAW/BAW filters are very important, in addition to the general characteristics mentioned above.…”

Section: Introductionmentioning

confidence: 99%

Behaviors of higher-order modes in I.H.P. SAW devices and discussion of their suppression

Nakagawa,

Ozasa,

Michigami

et al. 2024

Jpn. J. Appl. Phys.

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In this work, behaviors of higher-order modes in an I.H.P. SAW device with a layered LiTaO3/SiO2/SiN/Si substrate are investigated, and suppression techniques of them are discussed. First, variation of the higher-order mode responses with structural parameters are analyzed using two-dimensional FEM. Then, on the basis of the calculated data, structural parameters for higher-order modes suppression with keeping main mode characteristics are determined. In addition, effectiveness of the optimized structure is confirmed from the measured data of fabricated a one-port resonator and filters. In measured data, it is shown that higher-order modes in a specific frequency range are successfully suppressed, while main made characteristics such as Bode-Q, bandwidth, and TCF are almost equivalent with those of the conventional I.H.P. SAW resonators and filters.

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“…This stress distribution is the prime cause of acousto-migration. Highly oriented Al (111) thin film has been reported to resist acousto-migration on different piezoelectric wafers [16,17]. Hence in this study, we have explored the preferred oriented growth of Al along (111) crystallographic direction using Ti as an underlayer.…”

Section: Introductionmentioning

confidence: 99%

Growth and Characterization of Al (111) Thin Film on Piezoelectric Wafers for SAW Device Fabrication for Space Applications

Sahu

Karmakar

et al. 2022

Nanoarchitectonics

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Surface Acoustic Wave (SAW) filters provide precise frequency filtering in RF and IF range with a tiny footprint. Metallic thin films are the essence of such modern SAW filter technology. However, SAW filters realized using NiCr/Al thin films are limited to power levels of ~5 dBm at RF frequencies. This limitation on power level is due to the acousto-migration phenomenon in thin films at higher power levels. In order to enhance the power durability of SAW filters, the preferred oriented growth of Al along (111) crystallographic direction is one of the methods to reduce acousto-migration. This paper explores the growth and characterization of different metallization schemes (NiCr/Al & Ti/Al) on different piezoelectric wafers to achieve oriented Al (111) film growth. Metallic thin films were deposited using electron beam evaporation technique. High Resolution X-Ray Diffraction (HR-XRD) and Four Point Probe Method were used for crystallographic characterization and Sheet Resistance (SR) measurement, respectively. Atomic Force Microscopy (AFM) and surface profiler were used to characterize the surface morphology of the deposited films. FWHM of 4.12 degree of rocking curve on Al (111) peak has been achieved for Ti/Al metal film deposited on ST-X Quartz piezoelectric wafer along with low sheet resistance of 124 mΩ/sq. A deposition rate of 1 Å/s for Ti and 7 Å/s for Al at a deposition temperature of 100 °C gave the best FWHM value for Al (111) orientation on ST-X Quartz wafer. Space qualification tests were also successfully performed on Ti/Al metalized wafers under extreme environmental conditions. The results obtained in this work demonstrate the suitability of Ti as an under layer to grow preferred oriented Al film along (111) orientation and thus to be used in the fabrication of high-power SAW devices for space applications.

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High power durable SAW filter with epitaxial aluminium electrodes on 38.5/spl deg/ rotated Y-X LiTaO/sub 3/ by two-step process sequence in titanium intermediate layer

Cited by 12 publications

References 2 publications

Piezoelectric materials and their applications in radio frequency domain and telecommunications

Piezoelectric materials and their applications in radio frequency domain and telecommunications

Behaviors of higher-order modes in I.H.P. SAW devices and discussion of their suppression

Growth and Characterization of Al (111) Thin Film on Piezoelectric Wafers for SAW Device Fabrication for Space Applications

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