Thin Film Bulk Acoustic Wave Devices. Performance Optimization and Modeling

Dissertation

Research output: ThesisDissertationCollection of Articles

Abstract

Thin film bulk acoustic wave (BAW) resonators and filters operating in the GHz range are used in mobile phones for the most demanding filtering applications and complement the surface acoustic wave (SAW) based filters. Their main ad-vantages are small size and high performance at frequencies above 2 GHz. This work concentrates on the characterization, performance optimization, and mod-elling techniques of thin film BAW devices. Laser interferometric vibration measurements together with plate wave disper-sion modeling are used to extract the full set of elastic material parameters for sputter deposited ZnO, demonstrating a method for obtaining material data needed for accurate simulation of the devices. The effectiveness of the acoustic interference reflector used to isolate the vi-bration from the substrate is studied by 1-D modeling, 2-D finite element method and by electrical and laser interferometric measurements. It is found that the Q-value of reflector-based BAW resonators operating at 2 GHz is limited to approximately 2000 by mechanisms other than leakage through the reflector. Suppression of spurious resonances in ZnO resonators is studied in depth by modeling and measurements. It is verified that the approximate mode orthogo-nality is behind the suppression in boundary frame type ZnO devices operating in the piston mode, but also another narrow band mode suppression mechanism is found. A plate wave dispersion based 2-D simulation scheme for laterally acousti-cally coupled BAW resonator filters is developed and employed in designing of experimental devices, which show both good agreement with the model predic-tions and a remarkable 4.9 % relative bandwidth.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Kaivola, M., Supervisor, External person
Award date25 Feb 2011
Place of PublicationEspoo
Publisher
Print ISBNs978-951-38-7722-4
Electronic ISBNs978-951-38-7723-1
Publication statusPublished - 2011
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

bulk acoustic wave devices
optimization
resonators
acoustics
reflectors
thin films
retarding
filters
vibration measurement
wave dispersion
pistons
complement
lasers
narrowband
finite element method
leakage
simulation
bandwidth
interference

Keywords

  • thing film
  • bulk acoustic wave
  • BAW
  • AIN
  • ZnO
  • resonator
  • filter
  • GHz
  • microacoustic modeling
  • interferometric imaging

Cite this

@phdthesis{92d6efae5adf4d7890a5e1a3b64975a4,
title = "Thin Film Bulk Acoustic Wave Devices. Performance Optimization and Modeling: Dissertation",
abstract = "Thin film bulk acoustic wave (BAW) resonators and filters operating in the GHz range are used in mobile phones for the most demanding filtering applications and complement the surface acoustic wave (SAW) based filters. Their main ad-vantages are small size and high performance at frequencies above 2 GHz. This work concentrates on the characterization, performance optimization, and mod-elling techniques of thin film BAW devices. Laser interferometric vibration measurements together with plate wave disper-sion modeling are used to extract the full set of elastic material parameters for sputter deposited ZnO, demonstrating a method for obtaining material data needed for accurate simulation of the devices. The effectiveness of the acoustic interference reflector used to isolate the vi-bration from the substrate is studied by 1-D modeling, 2-D finite element method and by electrical and laser interferometric measurements. It is found that the Q-value of reflector-based BAW resonators operating at 2 GHz is limited to approximately 2000 by mechanisms other than leakage through the reflector. Suppression of spurious resonances in ZnO resonators is studied in depth by modeling and measurements. It is verified that the approximate mode orthogo-nality is behind the suppression in boundary frame type ZnO devices operating in the piston mode, but also another narrow band mode suppression mechanism is found. A plate wave dispersion based 2-D simulation scheme for laterally acousti-cally coupled BAW resonator filters is developed and employed in designing of experimental devices, which show both good agreement with the model predic-tions and a remarkable 4.9 {\%} relative bandwidth.",
keywords = "thing film, bulk acoustic wave, BAW, AIN, ZnO, resonator, filter, GHz, microacoustic modeling, interferometric imaging",
author = "Tuomas Pensala",
note = "CA2: TK610 CA: Cluster1 OH: V{\"a}it{\"o}skirja SDA: MEL Project code: 70339 PGN: 97 p. + app. 73 p.",
year = "2011",
language = "English",
isbn = "978-951-38-7722-4",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "756",
address = "Finland",
school = "Aalto University",

}

Thin Film Bulk Acoustic Wave Devices. Performance Optimization and Modeling : Dissertation. / Pensala, Tuomas.

Espoo : VTT Technical Research Centre of Finland, 2011. 108 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Thin Film Bulk Acoustic Wave Devices. Performance Optimization and Modeling

T2 - Dissertation

AU - Pensala, Tuomas

N1 - CA2: TK610 CA: Cluster1 OH: Väitöskirja SDA: MEL Project code: 70339 PGN: 97 p. + app. 73 p.

PY - 2011

Y1 - 2011

N2 - Thin film bulk acoustic wave (BAW) resonators and filters operating in the GHz range are used in mobile phones for the most demanding filtering applications and complement the surface acoustic wave (SAW) based filters. Their main ad-vantages are small size and high performance at frequencies above 2 GHz. This work concentrates on the characterization, performance optimization, and mod-elling techniques of thin film BAW devices. Laser interferometric vibration measurements together with plate wave disper-sion modeling are used to extract the full set of elastic material parameters for sputter deposited ZnO, demonstrating a method for obtaining material data needed for accurate simulation of the devices. The effectiveness of the acoustic interference reflector used to isolate the vi-bration from the substrate is studied by 1-D modeling, 2-D finite element method and by electrical and laser interferometric measurements. It is found that the Q-value of reflector-based BAW resonators operating at 2 GHz is limited to approximately 2000 by mechanisms other than leakage through the reflector. Suppression of spurious resonances in ZnO resonators is studied in depth by modeling and measurements. It is verified that the approximate mode orthogo-nality is behind the suppression in boundary frame type ZnO devices operating in the piston mode, but also another narrow band mode suppression mechanism is found. A plate wave dispersion based 2-D simulation scheme for laterally acousti-cally coupled BAW resonator filters is developed and employed in designing of experimental devices, which show both good agreement with the model predic-tions and a remarkable 4.9 % relative bandwidth.

AB - Thin film bulk acoustic wave (BAW) resonators and filters operating in the GHz range are used in mobile phones for the most demanding filtering applications and complement the surface acoustic wave (SAW) based filters. Their main ad-vantages are small size and high performance at frequencies above 2 GHz. This work concentrates on the characterization, performance optimization, and mod-elling techniques of thin film BAW devices. Laser interferometric vibration measurements together with plate wave disper-sion modeling are used to extract the full set of elastic material parameters for sputter deposited ZnO, demonstrating a method for obtaining material data needed for accurate simulation of the devices. The effectiveness of the acoustic interference reflector used to isolate the vi-bration from the substrate is studied by 1-D modeling, 2-D finite element method and by electrical and laser interferometric measurements. It is found that the Q-value of reflector-based BAW resonators operating at 2 GHz is limited to approximately 2000 by mechanisms other than leakage through the reflector. Suppression of spurious resonances in ZnO resonators is studied in depth by modeling and measurements. It is verified that the approximate mode orthogo-nality is behind the suppression in boundary frame type ZnO devices operating in the piston mode, but also another narrow band mode suppression mechanism is found. A plate wave dispersion based 2-D simulation scheme for laterally acousti-cally coupled BAW resonator filters is developed and employed in designing of experimental devices, which show both good agreement with the model predic-tions and a remarkable 4.9 % relative bandwidth.

KW - thing film

KW - bulk acoustic wave

KW - BAW

KW - AIN

KW - ZnO

KW - resonator

KW - filter

KW - GHz

KW - microacoustic modeling

KW - interferometric imaging

M3 - Dissertation

SN - 978-951-38-7722-4

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -