2020 50th European Microwave Conference (EuMC), 2021
The competition for the development of radio-frequency filters is still increasing with the immin... more The competition for the development of radio-frequency filters is still increasing with the imminence of the new telecommunication standard commercialization. Although investigated for years without real commercial breakthrough, the combination of piezoelectric films on Silicon is now receiving a very strong interest. In this contribution, we present the capability of Smart-Cut Piezo-On-Insulator (POI) substrates combining Lithium Tantalate and Silicon developed by SOITEC for the design and manufacturing of SAW filters. We particularly focus on one typical POI structure and we demonstrate its use for the design and fabrication of various filters taking advantage of the high performance modes enabled by the thin film perfect crystal structure on a frequency range starting from 400 MHz to 2.5 GHz and even more without changing the material stack.
Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addr... more Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addressing the problem of high frequency RF filters and frequency sources (above 1 GHz). In this paper, we propose an alternative to thin film deposition consisting in single crystal wafers bonded on substrate (high quality) and thinned down, allowing for plate thickness close to 30mum. This has
Low-power receivers use direct-detection receiver architecture for its design simplicity and its ... more Low-power receivers use direct-detection receiver architecture for its design simplicity and its low power dissipation. However, the direct-detection based receivers suffer from co-channel interference which significantly degrades the communication reliability. Co-channel interference robustness can be improved by using a BPSK Barker code modulated Surface Acoustic Wave (SAW) correlator as a prior stage to the RF direct detection circuit. This paper reports in details the design, fabrication and measurements of a 2.45 GHz SAW correlator with 13 bits length Barker code. The device is fabricated on Lithium Niobate LiNbO3 substrate and it is composed of an input non-coded Inter Digital Transducers (IDT), a Piezoelectric substrate and an output coded IDT. The device wavelength λ is set to 1.6 µm, considering a phase velocity of the wave equal to 3970 m.s-1. Several configurations of the device were designed and fabricated, particularly varying the aperture and the non-coded IDT length t...
This work is devoted to the reduction of temperature coefficient of frequency (TCF) of leaky-surf... more This work is devoted to the reduction of temperature coefficient of frequency (TCF) of leaky-surface-acoustic-wave (LSAW) on (YXl)/42° Lithium Tantalate. Compound single crystal substrates based on LiTaO3 wafers bonded onto Silicon and thinned down to some tens μm are manufactured in that way. The leading idea consists in impeding the natural Tantalate thermal expansion using Silicon limited expansion. 2 GHz resonators have been built on these compound wafers to demonstrate the principle. Temperature-controlled tip-probing tests show on-trench absolute TCF smaller than 7 pmm.K-1. A representative set of resonator has been packaged and tested in a climatic chamber, yielding evidence of TCF much smaller than the one of the single-crystal substrate and even temperature compensation. Perspective and further developments of this work are discussed as a conclusion.
2020 IEEE International Ultrasonics Symposium (IUS), 2020
High quality single crystal LiTaO3 thin film transfer using Smart Cut™ technology has been demons... more High quality single crystal LiTaO3 thin film transfer using Smart Cut™ technology has been demonstrated. Piezo On Insulator (POI) characteristics were optimized to the benefit of the guided SAW resonator performance. We will correlate these substrate parameters with some key figures of merit of guided SAW devices in terms of frequency control, k2, Q factor.
2014 European Frequency and Time Forum (EFTF), 2014
Increase of capillary permeability is the chief symptomatic reaction of various pathologic states... more Increase of capillary permeability is the chief symptomatic reaction of various pathologic states, especially that of localized inflammation, and this is the characteristic pharmacological properties of histamine at a far smaller concentration than that of any other chemical substances (Lewis, 1927; Crammer and Hele, 1944). There are numerous observations as to the diminishing effect of antihistamines on the flare and wheal caused by histamine and the inhibition by antihistamines of localized accumulation of intravenously injected dyes, such as trypan blue, referable to intradermal injection of histamine (for refs. cf. Loew, 1947; Feet al., 1950). As for the inhibition of capillary permeability by antihistamines, some maintain that this action is limited to the case where such permeability has been increased by histamine (Wells, Morris and Dragstedt, 1946; Netter, 1947; Rigdon, 1949), but no single and decisive conclusion can yet be given.
2011 International Symposium on Applications of Ferroelectrics (ISAF/PFM) and 2011 International Symposium on Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials, 2011
In this paper, we propose a new concept of acoustic resonator based on a waveguide structure. In ... more In this paper, we propose a new concept of acoustic resonator based on a waveguide structure. In the telecommunication market, composants used are indeed generally bases on Surface Acoustic Wave (SAW) or Bulk Acoustic Wave (BAW) devices. However, those systems present technological limits as short-circuits between the electrodes of the interdigital transducers (for SAW device) or the precise control of the piezoelectric material thick resonator (for BAW device). We suggest a new concept based on a periodically poled transducer (PPT) in a ferroelectric substrate (LiNbO 3 or LiTaO 3), embedded between two guiding substrates in order to create an acoustic waveguide. Periodically poled transducers have been investigated recently as an alternative to classical inter-digital transducers for the excitation and detection of guided acoustic waves. A resonator operating at 131MHz has been successfully fabricated and used in order to stabilize an oscillator at this frequency. However, the developed resonator presents a significant thermal sensitivity. The following experiments have consisted in studying a Si/thinned PPT layer/Si structure in order to reduce the thermal sensitivity.
2015 Joint IEEE International Symposium on the Applications of Ferroelectric (ISAF), International Symposium on Integrated Functionalities (ISIF), and Piezoelectric Force Microscopy Workshop (PFM), 2015
2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum, 2007
In this paper, we present new results on the development of piezoelectric transducers based on pe... more In this paper, we present new results on the development of piezoelectric transducers based on periodically poled ferroelectrics domains. The fabrication of test devices operating in the range 50-500 MHz has been achieved. Pure longitudinal modes are excited, yielding high frequency operation of test devices with easily achievable lithography process (20 and 10 µm periods). The dispersion analysis of our devices is reported and the capability of the proposed waveguide to support pure longitudinal modes along the plate radial dimension is emphasized
In this paper, we present new results on the development of piezoelectric transducers based on pe... more In this paper, we present new results on the development of piezoelectric transducers based on periodically poled ferroelectric domains on lithium niobate bonded on silicon. The fabrication of the periodically poled transducers operating in the range 50-500 MHz has been achieved on a 3" 500 mum thick wafer. These devices have then been bonded on a silicon wafer and thinned
2013 Joint European Frequency and Time Forum & International Frequency Control Symposium (EFTF/IFC), 2013
ABSTRACT In this paper, we present a wafer level approach to fabricate SAW pressure sensors on a ... more ABSTRACT In this paper, we present a wafer level approach to fabricate SAW pressure sensors on a single crystal AT-cut Quartz film transferred onto a bulk Silicon substrate. The final thickness of the quartz active layer was obtained using a combination of coarse mechanical thinning and fine polishing. Isolated Quartz membranes with a controlled thickness were then released by DRIE of the Silicon substrate. Details of the sensor fabrication process, modeling and electrical measurements are presented. In addition, theoretical considerations in good agreement with experimental results are disclosed.
New guiding principles and concepts are currently investigated for developing high frequency devi... more New guiding principles and concepts are currently investigated for developing high frequency devices capable to answer the RF manufacturer demand for telecommunication an remote transmission modern components. Beside the use of physically or chemically deposited piezoelectric overlays, the use of composite wafers composed by single crystal layers and wafers obtained by wafer bonding and lapping/polishing techniques offers attractive opportunities for overpassing the known limitations of acoustics-based radio-frequency devices. In this paper, we present different approaches for manufacturing such composite wafers and we describe different applications taking advantage of their unique characteristics. Lithium niobate is particularly considered for the piezoelectric layers because of its exceptional piezoelectric properties and its very high acoustic quality, and various substrate such as silicon, sapphire and lithium niobate again are used to guide and trap the excited waves. State-of-the-art Surface Acoustic Wave (SAW) devices, Harmonic Bulk Acoustic Resonators (HBARS) and Periodically Poled Transducers developed on such wafers are presented to illustrate the potential of this technological approach.
2020 Symposium on Design, Test, Integration & Packaging of MEMS and MOEMS (DTIP), 2020
In this paper the approach of improving aging of (AlCu2%) electrode of Surface acoustic Wave filt... more In this paper the approach of improving aging of (AlCu2%) electrode of Surface acoustic Wave filters is presented. The goal of this study is to contribute of the improving of aging due to electromigration effect. This effect occur easily in high-frequency Surface Acoustic Wave (SAW) devices. For that purpose, the impact of a tantalum (Ta) thickness deposited between the electrodes (AlCu2%) and a piezoelectric LiNbO3 is done. A heating post-process is also presented to increase the aging of such devices.
The development of new generations of telecommunication systems requires more and more components... more The development of new generations of telecommunication systems requires more and more components and radio-frequency (RF) modules to select and the process signals supporting the information. The solution the most used for this kind of application is always based on the principle of surface acoustic waves (SAW) and its associated components, taking into account their unique spectral quality (insertion losses, out of band rejection, group delay?), their design flexibility and their compactness for L- and S-bands. Although still commonly used today, filters on single-crystals such as lithium tantalate (LiTaO3) and lithium niobate (LiNbO3) cannot be used for future RF modules since the intrinsic stability of these substrates is far from being adapted to meet the challenges of modern telecommunications. To respond to this demands, a new generation of substrates is necessary. The main idea of the work presented here then consists in combining a thin piezoelectric film and a substrate ha...
2018 IEEE International Ultrasonics Symposium (IUS), 2018
This paper investigates advanced piezoelectric-on-insulator (POI) substrates elaborated using the... more This paper investigates advanced piezoelectric-on-insulator (POI) substrates elaborated using the Smart Cut™ technology to transfer a thin, high uniformity, single-crystal LiTaO3 layer on top of a silicon handle wafer. These POI substrates enable the development of high quality surface acoustic wave (SAW) devices. Single-port test resonator have been built on such wafers, reaching Bode Q in excess of 1700 and coupling factors above 8 %, as the result of guided mode propagation. Resonance frequency dispersion was measured as low as 0.64 %. The thin layer stack also improves TCF down to 5.8 ppm/°C compared with conventional bulk LiTaO3 technology and can be further reduced at desired frequencies by optimizing the multi-layer stack thicknesses.
2016 IEEE International Frequency Control Symposium (IFCS), 2016
In this paper, we present new results on the development of an original acoustic waveguides conce... more In this paper, we present new results on the development of an original acoustic waveguides concept based on a Periodically Poled Lithium Niobate transducer. Periodically poled transducers have been investigated recently as an alternative to classical inter-digital transducers for the excitation and detection of guided acoustic waves. We expose here two different structures of RF resonators based on this concept: a “Silicon/Gold layer/PPLN thin film/Gold layer/Silicon” stack and a PPLN-ridge structure. Simulations, fabrication and experimental results of both resonators are presented. “Si/10 μm-thick PPLN/Si” and “PPLN-ridge (11 μm-wide and 250 μm-deep)” resonators with a poling period of 50 μm have been achieved. The experimental admittances of these devices have pointed out the existence of an isolated mode operating at frequencies near 110 MHz for the stack structure and near 160 MHz with an electromechanical coupling of about 19 % for the ridge structure. These results are in agreement with the finite and boundary elements simulations.
2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC), 2019
In this paper, we present a new generation of substrates which address the demand for versatile i... more In this paper, we present a new generation of substrates which address the demand for versatile intermediate-to-large-band surface acoustic wave devices and provides a unique solution for temperature-stable filter with excellent spectral qualities. The Piezoelectric-On-Insulator (POI) layer structure provides a breakthrough solution for addressing modern filter challenges on an extended range of specification. An implementation example is presented for a GPS filter at 1.575 GHz exhibiting a TCF smaller than 10 ppm.K-1
Surface Acoustic Wave (SAW) sensors are small, passive and wireless devices. We present here the ... more Surface Acoustic Wave (SAW) sensors are small, passive and wireless devices. We present here the latest results obtained in a project aimed at developing a SAW-based implantable pressure sensor, equipped with a well-defined, 30 μm-thick, 4.7 mm-in-diameter, Lithium Niobate (LN) membrane. A novel fabrication process was used to solve the issue of accurate membrane etching in LN. LN/Si wafers were fabricated first, using wafer-bonding techniques. Grinding/polishing operations followed, to reduce the LN thickness to 30 μm. 2.45 GHz SAW Reflective Delay-Lines (R-DL) were then deposited on LN, using a combination of e-beam and optical lithography. The R-DL was designed in such a way as to allow for easy temperature compensation. Eventually, the membranes were etched in Si. A dedicated set-up was implemented, to characterize the sensors versus pressure and temperature. The achieved pressure accuracy is satisfactory (±0.56 mbar). However, discontinuities in the response curve and residual ...
2020 50th European Microwave Conference (EuMC), 2021
The competition for the development of radio-frequency filters is still increasing with the immin... more The competition for the development of radio-frequency filters is still increasing with the imminence of the new telecommunication standard commercialization. Although investigated for years without real commercial breakthrough, the combination of piezoelectric films on Silicon is now receiving a very strong interest. In this contribution, we present the capability of Smart-Cut Piezo-On-Insulator (POI) substrates combining Lithium Tantalate and Silicon developed by SOITEC for the design and manufacturing of SAW filters. We particularly focus on one typical POI structure and we demonstrate its use for the design and fabrication of various filters taking advantage of the high performance modes enabled by the thin film perfect crystal structure on a frequency range starting from 400 MHz to 2.5 GHz and even more without changing the material stack.
Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addr... more Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addressing the problem of high frequency RF filters and frequency sources (above 1 GHz). In this paper, we propose an alternative to thin film deposition consisting in single crystal wafers bonded on substrate (high quality) and thinned down, allowing for plate thickness close to 30mum. This has
Low-power receivers use direct-detection receiver architecture for its design simplicity and its ... more Low-power receivers use direct-detection receiver architecture for its design simplicity and its low power dissipation. However, the direct-detection based receivers suffer from co-channel interference which significantly degrades the communication reliability. Co-channel interference robustness can be improved by using a BPSK Barker code modulated Surface Acoustic Wave (SAW) correlator as a prior stage to the RF direct detection circuit. This paper reports in details the design, fabrication and measurements of a 2.45 GHz SAW correlator with 13 bits length Barker code. The device is fabricated on Lithium Niobate LiNbO3 substrate and it is composed of an input non-coded Inter Digital Transducers (IDT), a Piezoelectric substrate and an output coded IDT. The device wavelength λ is set to 1.6 µm, considering a phase velocity of the wave equal to 3970 m.s-1. Several configurations of the device were designed and fabricated, particularly varying the aperture and the non-coded IDT length t...
This work is devoted to the reduction of temperature coefficient of frequency (TCF) of leaky-surf... more This work is devoted to the reduction of temperature coefficient of frequency (TCF) of leaky-surface-acoustic-wave (LSAW) on (YXl)/42° Lithium Tantalate. Compound single crystal substrates based on LiTaO3 wafers bonded onto Silicon and thinned down to some tens μm are manufactured in that way. The leading idea consists in impeding the natural Tantalate thermal expansion using Silicon limited expansion. 2 GHz resonators have been built on these compound wafers to demonstrate the principle. Temperature-controlled tip-probing tests show on-trench absolute TCF smaller than 7 pmm.K-1. A representative set of resonator has been packaged and tested in a climatic chamber, yielding evidence of TCF much smaller than the one of the single-crystal substrate and even temperature compensation. Perspective and further developments of this work are discussed as a conclusion.
2020 IEEE International Ultrasonics Symposium (IUS), 2020
High quality single crystal LiTaO3 thin film transfer using Smart Cut™ technology has been demons... more High quality single crystal LiTaO3 thin film transfer using Smart Cut™ technology has been demonstrated. Piezo On Insulator (POI) characteristics were optimized to the benefit of the guided SAW resonator performance. We will correlate these substrate parameters with some key figures of merit of guided SAW devices in terms of frequency control, k2, Q factor.
2014 European Frequency and Time Forum (EFTF), 2014
Increase of capillary permeability is the chief symptomatic reaction of various pathologic states... more Increase of capillary permeability is the chief symptomatic reaction of various pathologic states, especially that of localized inflammation, and this is the characteristic pharmacological properties of histamine at a far smaller concentration than that of any other chemical substances (Lewis, 1927; Crammer and Hele, 1944). There are numerous observations as to the diminishing effect of antihistamines on the flare and wheal caused by histamine and the inhibition by antihistamines of localized accumulation of intravenously injected dyes, such as trypan blue, referable to intradermal injection of histamine (for refs. cf. Loew, 1947; Feet al., 1950). As for the inhibition of capillary permeability by antihistamines, some maintain that this action is limited to the case where such permeability has been increased by histamine (Wells, Morris and Dragstedt, 1946; Netter, 1947; Rigdon, 1949), but no single and decisive conclusion can yet be given.
2011 International Symposium on Applications of Ferroelectrics (ISAF/PFM) and 2011 International Symposium on Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials, 2011
In this paper, we propose a new concept of acoustic resonator based on a waveguide structure. In ... more In this paper, we propose a new concept of acoustic resonator based on a waveguide structure. In the telecommunication market, composants used are indeed generally bases on Surface Acoustic Wave (SAW) or Bulk Acoustic Wave (BAW) devices. However, those systems present technological limits as short-circuits between the electrodes of the interdigital transducers (for SAW device) or the precise control of the piezoelectric material thick resonator (for BAW device). We suggest a new concept based on a periodically poled transducer (PPT) in a ferroelectric substrate (LiNbO 3 or LiTaO 3), embedded between two guiding substrates in order to create an acoustic waveguide. Periodically poled transducers have been investigated recently as an alternative to classical inter-digital transducers for the excitation and detection of guided acoustic waves. A resonator operating at 131MHz has been successfully fabricated and used in order to stabilize an oscillator at this frequency. However, the developed resonator presents a significant thermal sensitivity. The following experiments have consisted in studying a Si/thinned PPT layer/Si structure in order to reduce the thermal sensitivity.
2015 Joint IEEE International Symposium on the Applications of Ferroelectric (ISAF), International Symposium on Integrated Functionalities (ISIF), and Piezoelectric Force Microscopy Workshop (PFM), 2015
2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum, 2007
In this paper, we present new results on the development of piezoelectric transducers based on pe... more In this paper, we present new results on the development of piezoelectric transducers based on periodically poled ferroelectrics domains. The fabrication of test devices operating in the range 50-500 MHz has been achieved. Pure longitudinal modes are excited, yielding high frequency operation of test devices with easily achievable lithography process (20 and 10 µm periods). The dispersion analysis of our devices is reported and the capability of the proposed waveguide to support pure longitudinal modes along the plate radial dimension is emphasized
In this paper, we present new results on the development of piezoelectric transducers based on pe... more In this paper, we present new results on the development of piezoelectric transducers based on periodically poled ferroelectric domains on lithium niobate bonded on silicon. The fabrication of the periodically poled transducers operating in the range 50-500 MHz has been achieved on a 3" 500 mum thick wafer. These devices have then been bonded on a silicon wafer and thinned
2013 Joint European Frequency and Time Forum & International Frequency Control Symposium (EFTF/IFC), 2013
ABSTRACT In this paper, we present a wafer level approach to fabricate SAW pressure sensors on a ... more ABSTRACT In this paper, we present a wafer level approach to fabricate SAW pressure sensors on a single crystal AT-cut Quartz film transferred onto a bulk Silicon substrate. The final thickness of the quartz active layer was obtained using a combination of coarse mechanical thinning and fine polishing. Isolated Quartz membranes with a controlled thickness were then released by DRIE of the Silicon substrate. Details of the sensor fabrication process, modeling and electrical measurements are presented. In addition, theoretical considerations in good agreement with experimental results are disclosed.
New guiding principles and concepts are currently investigated for developing high frequency devi... more New guiding principles and concepts are currently investigated for developing high frequency devices capable to answer the RF manufacturer demand for telecommunication an remote transmission modern components. Beside the use of physically or chemically deposited piezoelectric overlays, the use of composite wafers composed by single crystal layers and wafers obtained by wafer bonding and lapping/polishing techniques offers attractive opportunities for overpassing the known limitations of acoustics-based radio-frequency devices. In this paper, we present different approaches for manufacturing such composite wafers and we describe different applications taking advantage of their unique characteristics. Lithium niobate is particularly considered for the piezoelectric layers because of its exceptional piezoelectric properties and its very high acoustic quality, and various substrate such as silicon, sapphire and lithium niobate again are used to guide and trap the excited waves. State-of-the-art Surface Acoustic Wave (SAW) devices, Harmonic Bulk Acoustic Resonators (HBARS) and Periodically Poled Transducers developed on such wafers are presented to illustrate the potential of this technological approach.
2020 Symposium on Design, Test, Integration & Packaging of MEMS and MOEMS (DTIP), 2020
In this paper the approach of improving aging of (AlCu2%) electrode of Surface acoustic Wave filt... more In this paper the approach of improving aging of (AlCu2%) electrode of Surface acoustic Wave filters is presented. The goal of this study is to contribute of the improving of aging due to electromigration effect. This effect occur easily in high-frequency Surface Acoustic Wave (SAW) devices. For that purpose, the impact of a tantalum (Ta) thickness deposited between the electrodes (AlCu2%) and a piezoelectric LiNbO3 is done. A heating post-process is also presented to increase the aging of such devices.
The development of new generations of telecommunication systems requires more and more components... more The development of new generations of telecommunication systems requires more and more components and radio-frequency (RF) modules to select and the process signals supporting the information. The solution the most used for this kind of application is always based on the principle of surface acoustic waves (SAW) and its associated components, taking into account their unique spectral quality (insertion losses, out of band rejection, group delay?), their design flexibility and their compactness for L- and S-bands. Although still commonly used today, filters on single-crystals such as lithium tantalate (LiTaO3) and lithium niobate (LiNbO3) cannot be used for future RF modules since the intrinsic stability of these substrates is far from being adapted to meet the challenges of modern telecommunications. To respond to this demands, a new generation of substrates is necessary. The main idea of the work presented here then consists in combining a thin piezoelectric film and a substrate ha...
2018 IEEE International Ultrasonics Symposium (IUS), 2018
This paper investigates advanced piezoelectric-on-insulator (POI) substrates elaborated using the... more This paper investigates advanced piezoelectric-on-insulator (POI) substrates elaborated using the Smart Cut™ technology to transfer a thin, high uniformity, single-crystal LiTaO3 layer on top of a silicon handle wafer. These POI substrates enable the development of high quality surface acoustic wave (SAW) devices. Single-port test resonator have been built on such wafers, reaching Bode Q in excess of 1700 and coupling factors above 8 %, as the result of guided mode propagation. Resonance frequency dispersion was measured as low as 0.64 %. The thin layer stack also improves TCF down to 5.8 ppm/°C compared with conventional bulk LiTaO3 technology and can be further reduced at desired frequencies by optimizing the multi-layer stack thicknesses.
2016 IEEE International Frequency Control Symposium (IFCS), 2016
In this paper, we present new results on the development of an original acoustic waveguides conce... more In this paper, we present new results on the development of an original acoustic waveguides concept based on a Periodically Poled Lithium Niobate transducer. Periodically poled transducers have been investigated recently as an alternative to classical inter-digital transducers for the excitation and detection of guided acoustic waves. We expose here two different structures of RF resonators based on this concept: a “Silicon/Gold layer/PPLN thin film/Gold layer/Silicon” stack and a PPLN-ridge structure. Simulations, fabrication and experimental results of both resonators are presented. “Si/10 μm-thick PPLN/Si” and “PPLN-ridge (11 μm-wide and 250 μm-deep)” resonators with a poling period of 50 μm have been achieved. The experimental admittances of these devices have pointed out the existence of an isolated mode operating at frequencies near 110 MHz for the stack structure and near 160 MHz with an electromechanical coupling of about 19 % for the ridge structure. These results are in agreement with the finite and boundary elements simulations.
2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC), 2019
In this paper, we present a new generation of substrates which address the demand for versatile i... more In this paper, we present a new generation of substrates which address the demand for versatile intermediate-to-large-band surface acoustic wave devices and provides a unique solution for temperature-stable filter with excellent spectral qualities. The Piezoelectric-On-Insulator (POI) layer structure provides a breakthrough solution for addressing modern filter challenges on an extended range of specification. An implementation example is presented for a GPS filter at 1.575 GHz exhibiting a TCF smaller than 10 ppm.K-1
Surface Acoustic Wave (SAW) sensors are small, passive and wireless devices. We present here the ... more Surface Acoustic Wave (SAW) sensors are small, passive and wireless devices. We present here the latest results obtained in a project aimed at developing a SAW-based implantable pressure sensor, equipped with a well-defined, 30 μm-thick, 4.7 mm-in-diameter, Lithium Niobate (LN) membrane. A novel fabrication process was used to solve the issue of accurate membrane etching in LN. LN/Si wafers were fabricated first, using wafer-bonding techniques. Grinding/polishing operations followed, to reduce the LN thickness to 30 μm. 2.45 GHz SAW Reflective Delay-Lines (R-DL) were then deposited on LN, using a combination of e-beam and optical lithography. The R-DL was designed in such a way as to allow for easy temperature compensation. Eventually, the membranes were etched in Si. A dedicated set-up was implemented, to characterize the sensors versus pressure and temperature. The achieved pressure accuracy is satisfactory (±0.56 mbar). However, discontinuities in the response curve and residual ...
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Papers by Emilie Courjon