FBAR Resonators with Sufficient High Q for RF Filter Implementation

et al. 2015

Sci Rep

The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3–2.2 GHz, d is ~9 μm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass.

Section: Resultssupporting

confidence: 88%

Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

Chen

Zhao

et al. 2015

Sci Rep

“…The development of compact, low cost, high-performance resonators is meant to respond to the growing demand of single-chip, highly integrated sensor (arrays) for (bio)chemical sensing applications, − and multiband radio frequency (RF) solutions for advanced wireless communication systems. − Micro- and nanoelectromechanical (MEMS/NEMS) resonators for sensor and RF applications have been widely explored because of their small size, light weight, low loss, and high IC integration capability. − Recently, the development of nanomaterials such as nanotubes, , nanowires, graphene, and other 2D nanomaterials, have opened new research interests in MEMS/NEMS resonator design and fabrications. In any case, micro/nano fabricated resonators are designed to work at appropriate frequency for specific applications.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, resonator sensor arrays need to work at the same resonant frequency to simplify the test system in applications such as real-time multiplexed sensing . In the field of RF wireless communication, resonators are widely integrated into very large scale integrated circuits (VLSI) as filters, oscillators, phase locking loops (PLL) and other electronic components, all of them are supposed to operate at a given frequency in accordance with the peripheral circuit or communication protocol. ,, However, due to the variations in semiconductor fabrication processes, micro/nano fabricated resonators are prone to deviate from the desired working frequency and could have large resonant frequency distribution at wafer scale (see Supporting Information). The solution leads to the technique of “frequency tuning” which normally requires multisteps of semiconductor fabrications to adjust the thickness of the resonators.…”

Section: Introductionmentioning

confidence: 99%

“…Molecular LbL self-assembly is first introduced by assembling positively and negatively charged polyelectrolytes in a layer by layer fashion through electrostatic interactions . It has been applied as an efficient surface modification technique for medical and biological applications. − Here, we utilize LbL assembly of poly(acrylic acid) (PAA) and poly(4-vinylpyridine) (PVP) on the resonator surface to tune the resonant frequency of a microfabricated thin film resonatorfilm bulk acoustic wave resonator (FBAR) . Due to its selective deposition onto the resonator surface without contaminating the gold pads with careful chemical design, the LbL tuning technique has the advantages of mask-less fabrication, high tuning resolution, and wide tuning range.…”

Section: Introductionmentioning

confidence: 99%

“…24−26 Here, we utilize LbL assembly of poly(acrylic acid) (PAA) and poly(4-vinylpyridine) (PVP) on the resonator surface to tune the resonant frequency of a microfabricated thin film resonatorfilm bulk acoustic wave resonator (FBAR). 9 Due to its selective deposition onto the resonator surface without contaminating the gold pads with careful chemical design, the LbL tuning technique has the advantages of mask-less fabrication, high tuning resolution, and wide tuning range. It avoids the high-cost semiconductor process and is able to tune the individual device to the desired frequency.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tuning the Resonant Frequency of Resonators Using Molecular Surface Self-assembly Approach

Liu

ACS Appl. Mater. Interfaces

et al. 2014

In this work, a new method to tune the resonant frequency of microfabricated resonator using molecular layer-by-layer (LbL) self-assembly approach is demonstrated. By simply controlling the polymer concentration and the number of layers deposited, precisely tuning the frequency of microfabricated resonators is realized. Due to its selective deposition through specific molecular recognitions, such technique avoids the high-cost and complex steps of conventional semiconductor fabrications and is able to tune individual diced device. Briefly, film bulk acoustic resonator (FBAR) is used to demonstrate the tuning process and two types of LbL deposition methods are compared. The film thickness and morphology have been characterized by UV-vis reflection spectra, ellipsometer and AFM. As a result, the maximum resonant frequency shift of FBAR reaches more than 20 MHz, meaning 1.4% tunability at least. The minimum frequency shift is nearly 10 kHZ per bilayer, indicating 7 ppm tuning resolution. Pressure cooker test (PCT) is performed to evaluate the reliability of LbL coated FBAR. Furthermore, applications for wireless broadband communication and chemical sensors of LbL coated FBAR have been demonstrated.

Effects of surface impedance on current density in a piezoelectric resonator for impedance distribution sensing

Liu

Appl. Math. Mech.-Engl. Ed.

et al. 2021

We study the relationship between the surface mechanical load represented by distributed acoustic impedance and the current density distribution in a shear mode piezoelectric plate acoustic wave resonator. A theoretical analysis based on the theory of piezoelectricity and trigonometric series is performed. In the specific and basic case when the surface load is due to a local mass layer, numerical results show that the current density concentrates under the mass layer and is sensitive to the physical as well as geometric parameters of the mass layer such as its location and size. This provides the theoretical foundation for predicting the surface impedance pattern from the current density distribution, which is fundamental to the relevant acoustic wave sensors.