7E-1 An Air-Gap Type FBAR Filter Fabricated Using a Thin Sacrificed Layer on a Flat Substrate

Taniguchi, S.; Yokoyama, Tsuyoshi; Iwaki, Masafumi; Nishihara, Tokihiro; Ueda, Masahiko; Satoh, Y.

doi:10.1109/ultsym.2007.156

Cited by 33 publications

(27 citation statements)

References 6 publications

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“…The main structural feature was that the airgap type FBAR has an air gap beneath the resonator, which has a dome shape controlled by film stress. The details of the fabrication process are reported in [33]. Mg and Zr or Mg and Hf concentrations were measured with an electron probe microanalyser (EPMA) to be 0.13.…”

Section: B Fbar Evaluationmentioning

confidence: 99%

“…Akiyama et al reported that substitution of aluminum (Al) by scandium (Sc) increases the piezoelectric coefficient d 33 of scandium aluminum nitride (Sc x Al 1−x N) thin film at x = 0.43 by approximately 400% in comparison with pure AlN [5]- [14]. This experimental result was explained by first-principles calculations in which the observed large increase in d 33 is caused by an intrinsic alloying effect and is related to an increase in the piezoelectric constant (e 33 ) in conjunction with a decrease in the elastic constant (C 33 ) [7]. Furthermore, Sc-doped AlN-based BAW resonators have been confirmed to have large electromechanical coupling coefficients [9]- [11], and for this reason, their thin films have attracted significant interest.…”

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confidence: 94%

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Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

Yokoyama

Iwazaki

Onda

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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We report piezoelectric materials composed of charge-compensated co-doped (Mg, β)(x)Al(1-x)N (β = Zr or Hf) thin films. The effect of the dopant element into AlN on the crystal structure, and piezoelectric properties of co-doped AlN was determined on the basis of a first-principles calculation, and the theoretical piezoelectric properties were confirmed by experimentally depositing thin films of magnesium (Mg) and zirconium (Zr) co-doped AlN (Mg-Zr-doped AlN). The Mg-Zrdoped AlN thin films were prepared on Si (100) substrates by using a triple-radio-frequency magnetron reactive co-sputtering system. The crystal structures and piezoelectric coefficients (d33) were investigated as a function of the concentrations, which were measured by X-ray diffraction and a piezometer. The results show that the d33 of Mg-Zr-doped AlN at total Mg and Zr concentrations (both expressed as β) of 0.35 was 280% larger than that of pure AlN. The experimentally measured parameter of the crystal structure and d33 of Mg-Zr-doped AlN (plotted as functions of total Mg and Zr concentrations) were in very close agreement with the corresponding values obtained by the first-principle calculations. Thin film bulk acoustic wave resonators (FBAR) employing (Mg,Zr)0.13Al0.87N and (Mg, Hf)0.13 Al0.87N as a piezoelectric thin film were fabricated, and their resonant characteristics were evaluated. The measured electromechanical coupling coefficient increased from 7.1% for pure AlN to 8.5% for Mg-Zr-doped AlN and 10.0% for Mg- Hf-doped AlN. These results indicate that co-doped (Mg, β)(x)Al(1-x)N (β = Zr or Hf) films have potential as piezoelectric thin films for wideband RF applications.

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Section: B Fbar Evaluationmentioning

confidence: 99%

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confidence: 94%

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

Yokoyama

Iwazaki

Onda

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…A main structural feature is that the air-gap type FBAR has an air gap beneath the resonator, which is a dome shape controlled by film stress. The details of the fabrication process are reported in [31]. For electrical and mechanical analysis of the fabricated FBARs, the measured impedance characteristics of the FBAR were fitted to a modified Butterworth Van Dyke (MBVD) equivalent circuiut [32] (shown in Fig.…”

Section: B Fbar Evaluationmentioning

confidence: 99%

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

Yokoyama

Iwazaki

Onda

et al. 2014

2014 IEEE International Ultrasonics Symposium

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In this paper, we report new piezoelectric materials composed of charge-compensated co-doped (Mg, ) x Al 1-x N ( = Zr or Hf). The effect of the dopant element into AlN on chemical stability, crystal structure, and piezoelectric property of co-doped AlN was determined on the basis of first-principles calculation, and the theoretical piezoelectric property was confirmed by experimentally depositing thin films of magnesium (Mg) and zirconium (Zr) co-doped AlN (Mg-Zr-doped AlN). The Mg-Zrdoped AlN thin films were prepared on Si (100) substrates by a triple-radio-frequency magnetron reactive co-sputtering system. The crystal structures and piezoelectric coefficients (d 33 ) of the films were investigated as a function of their concentrations, which were measured by X-ray diffraction and a piezometer. The investigation results show that d 33 of Mg-Zr-doped AlN at total Mg and Zr concentrations (both expressed as x) of 0.35 is 280% larger than that of pure AlN. The experimentally measured parameter of the crystal structure and d 33 of Mg-Zr-doped AlN (plotted as functions of total Mg and Zr concentrations) are in very close agreement with the corresponding values obtained by first-principle calculations. Thin film bulk acoustic wave resonators (FBARs) employing (Mg,Zr) 0.13 Al 0.87 N and (Mg,Hf) 0.13 Al 0.87 N as a piezoelectric thin film were fabricated, and their resonant characteristics were evaluated. As a result, the measured electromechanical coupling coefficient was found to increase from 7.1% (for pure AlN) to 8.5% for Mg-Zr-doped AlN and 10.0% for Mg-Hf-doped AlN. These results indicate that codoped (Mg, ) x Al 1-x N ( = Zr or Hf) films have potential as piezoelectric thin films for wideband RF applications.

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“…In this layout, the two filter dies and matching components were mounted on an approximately 3 x 3 mm 2 laminated board. The compactness compares to the smallest duplexers reported so far [14][15][16][17]. By performing 3-dimensional electro-magnetic (EM) simulations for the duplexer model, the leakage not via the signal line was estimated and controlled.…”

Section: Demonstration Of Prototypesmentioning

confidence: 99%

A design technique to enhance isolation of duplexer in single-ended and differential modes

Tsutsumi

Inoue

Iwaki

et al. 2011

2011 IEEE International Ultrasonics Symposium

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This paper describes a design technique to enhance isolation of acoustic duplexers in the single-ended and the differential modes for a so-called "inter-stage SAW-less" radio frequency (RF) front-end of cellular phones. The leakage signal from the Tx to the Rx ports existing inside the duplexer, which degrades the isolation characteristics, is cancelled out by utilizing a proposed circuit topology and by performing careful design of the whole duplexer structure. The principle directly enhances the single-ended isolation, but it also contributes to improve the differential mode isolation. The prototypes for the single-ended and differential duplexers exhibit isolation higher than 70 dB and 65 dB, respectively, in the Tx band for UMTS Band 1 application.

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7E-1 An Air-Gap Type FBAR Filter Fabricated Using a Thin Sacrificed Layer on a Flat Substrate

Cited by 33 publications

References 6 publications

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications

A design technique to enhance isolation of duplexer in single-ended and differential modes

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