title: Tuning the resonant frequency of resonators using molecular surface self-assembly approach.
abstract: 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.
authors.affiliation: State Key Laboratory of Precision Measuring Technology & Instruments, College of Precision Instrument and Optoelectronics Engineering, Tianjin University , Tianjin 300072, China.
authors.forename: Wenpeng
authors.initials: W
authors.lastname: Liu
authors.forename: Jingwei
authors.initials: J
authors.lastname: Wang
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yu
authors.forename: Ye
authors.initials: Y
authors.lastname: Chang
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Hemi
authors.initials: H
authors.lastname: Qu
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Pang
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Daihua
authors.initials: D
authors.lastname: Zhang
authors.forename: Huaping
authors.initials: H
authors.lastname: Xu
authors.forename: Xuexin
authors.initials: X
authors.lastname: Duan
mesh_terms: D000162:Acoustics; D000180:Acrylic Resins / Q000737:chemistry*; D000465:Algorithms; D004784:Environmental Monitoring / Q000379:methods; D005374:Filtration; D005740:Gases; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000737:chemistry*; D011144:Polyvinylpyridine N-Oxide / Q000737:chemistry*; D011312:Pressure; D015203:Reproducibility of Results; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D005740:Gases; D014867:Water; C006903:carbopol 940; D011144:Polyvinylpyridine N-Oxide; D010100:Oxygen
keywords: film bulk acoustic resonator (FBAR); frequency tuning; gas sensor; layer-by-layer (LbL) self-assembly; resonators