【公開日：2024.07.25】【最終更新日：2024.06.10】
課題データ / Project Data
課題番号 / Project Issue Number
23OS1043
利用課題名 / Title
水晶音叉の表面へのドットパターン作製
利用した実施機関 / Support Institute
大阪大学 / Osaka Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）加工・デバイスプロセス/Nanofabrication（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）高度なデバイス機能の発現を可能とするマテリアル/Materials allowing high-level device functions to be performed（副 / Sub）-
キーワード / Keywords
Silicon-based materials and devices, Piezoelectric materials, Quartz and Glass materials, Electron beam lithography, Wet etching,
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
Mona Yadi
所属名 / Affiliation
大阪大学大学院工学研究科 機械工学科 （高谷・水谷研究室）
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
近田和美
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術補助/Technical Assistance
利用した主な設備 / Equipment Used in This Project
OS-103：超高精細電子ビームリソグラフィー装置
OS-110：リアクティブイオンエッチング装置
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Understanding and accurately analyzing the mechanical properties of microelectromechanical systems (MEMS) is essential for assessing their device functionality and performance. Precisely measuring the dynamic properties of a quartz tuning fork (QTF), for instance, can significantly enhance the accurate evaluation of tip-sample forces in a QTF-based scanning probe microscopy system. Current methods, such as analytical and numerical approaches, have limitations when it comes to providing accurate measurements. To overcome these limitations, we proposed an experimental approach that combines stroboscopic and sampling moiré (SM) techniques. Our method focuses on investigating the in-plane vibration behavior of a QTF and utilizes the obtained results to measure its mechanical parameters. To achieve this, we used Electron Beam Lithography (EBL) and Reactive Ion Etch (RIE) devices respectively to etch micron size square patterns with a specific pitch size in the whole surface of the MEMS device then we synchronized nanometer-scale light pulses, generated using a custom-designed stroboscope, with the QTF's excitation voltage, to effectively freeze high-speed vibrations. The Sample's oscillation was then observed using a standard CCD camera. Subsequently, SM analysis was employed to extract the surface vibration profile, facilitating the measurement of dynamic properties. This technique has the potential to control the quality of various MEMS sensors that are compatible with the sample preparation process.
実験 / Experimental
The entire schematic of the experimental setup is
presented comprehensively in Figure 1, where the upper section pertains to the
optical setup, while the lower portion shows the logical and electrical configuration of
the system. To manage the operation, two function generators are deployed. FG1 is responsible for generating input sinusoidal signals for the QTF with a
first resonance frequency of 32.768KHZ. Simultaneously, FG2 generates pulse
signals to drive the strobe. To ensure
precise synchronization between these generators, a master oscillator was
separately applied to FG1 as a 10 MHZ clock. Synchronization
between two FGs was achieved through a custom
LabVIEW program, granting precise control and coordination over signal specifications
as well as timing and phase relationships between the two signal sources. Imaging is executed through the optical setup,
capturing the relevant data. Subsequently, the electric charge generated on the surface of the
QTF is routed back to the QTF driver. This charge is then converted into voltage using a transimpedance amplifier (TIA),
rendering it readable for the lock-in
amplifier. The acquired data is then saved to a
computer through a data acquisition
(DAQ) card.
Figure 2 illustrates the
cross-sectional view of a QTF utilized in this study, where gold electrodes are affixed to the surface of the quartz using an adhesive. The
precise thickness of the gold and adhesive layers is not provided by the
manufacturer, necessitating a degree of trial and error to develop an effective
recipe for etching patterns on the QTF’s surface. This process is critical for employing the SM method [1], which requires a uniform square pattern across the
entire surface of the sample. As shown in Figure 2, the sample preparation process
for the SM method is defined in several steps, labeled from (b) to (d).
Initially, the photoresist material ZEP520A (ZEP: Styrene Methyl Acrylate-based
positive e-beam resist), with a depth of 300 nm, is coated on the QTF’s
surface, as depicted in step (b) (Opticoat spin coater (MS-A150) is used). This
base layer is essential for subsequent pattern creation. Next, using an
electron beam lithography device like the Elionix ELS-100T, square patterns with
40μm sides and a pitch of 40μm are crafted, as visualized in step (c). This
process took one and a half hours. The reactive ion etching process follows, utilizing a device such as the Samco-UCP RIE-10NR to etch the square patterns into
the QTF’s gold electrodes. This etching takes 45 minutes at a rate of 8.43
nm/min, represented in step (d). In order to clean the samples from the remaining
resist material the whole sample was deepened into a 3:2 mixture of dimethyl sulfoxide
and N-methyl-2-pyrrolidone for 12 hours and then cleaned with a UV ozone cleaning
device (Samco UV-1). In order to save time and money, this process can be done
by the manufacturer during affixing electrodes on the surface of the specimen.
結果と考察 / Results and Discussion
Figure 3a presents the recorded brightness data associated with the QTF for the 24th camera frame. Three dots, distinguished by their colors (red, blue, and green), indicate specific locations on the sample being examined. In Figure 3b we can observe the displacement distribution of the QTF for the same frame or time period, coinciding with one complete cycle of the QTF's vibration. This visualization also illustrates the mode shape corresponding to the first resonance frequency of the QTF.Figure 4 provides three waveforms illustrating the vibration amplitudes of the QTF at the positions corresponding to the three dots. The three dots marked within this figure represent the associated results calculated in the time domain, specifically related to frame number 24. As expected, we can observe three complete cycles of vibration occurring within one second, perfectly aligned with the applied beat frequency (frequency difference between QTF driver signal and Strobe signal). These three vibration cycles collectively account for a duration of 91.62 microseconds within the QTF's oscillation time domain. When comparing the red and blue dots, noticeable variations in vibration amplitude become apparent at two distinct locations along the length of the QTF's prong. Conversely, a comparison between the red and green dots draws attention to the phase difference between the vibrating signals originating from the two prongs of the QTF. Figure 3b effectively illustrates that these investigations can be conducted seamlessly across the entire surface of the QTF simultaneously. This capability greatly facilitates the detection of mode shapes and other mechanical parameters such as resonance frequency, quality factor, and spring constant of the sensor.
図・表・数式 / Figures, Tables and Equations
Fig. 1 : Optical and electrical configuration
Fig. 2: Sample preparation procedure; (a) QTF's cross-section (b) Resist coating (c) Electron beam lithography (d) Dry etching
Fig. 3 : (a) QTF's 24th recorded image
Fig. 3: (b) Displacement distribution
Fig. 4: Comparison of vibration amplitude of three dots located in figure 3(a)
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
References : [1] Yadi, M., Morimoto, Y., Ueki, M. and Takaya, Y., 2021. In-plane vibration detection using sampling moiré method. Journal of Physics: Photonics , 3 (2), p.024005 .Yadi, M., Morimoto, Y., Ueki, M. and Takaya, Y., 2021. In-plane vibration detection using sampling moiré method. Journal of Physics: Photonics 3 , (2), p.024005. Acknowledgments: I'd like to express my gratitude to Konda San (近田 和美) for her patience and kindness. Despite my inability to speak Japanese, she made every effort to assist me in understanding device operations and troubleshooting during our research. Her invaluable guidance and support were instrumental, and I learned a great deal from her expertise. This work would not have been possible without her assistance.
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
-
Mona Yadi, Stroboscopic sampling Moiré microscope (SSMM) for investigation of QTF’s mechanical properties, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XXI, , 3(2024).
DOI: https://doi.org/10.1117/12.3002171
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
- Mona Yadi , Tsutomu Uenohara , Yasuhiro Mizutani , Yoshiharu Morimoto , Yasuhiro Takaya, “Stroboscopic sampling moiré microscope (SSMM) for investigation of MEMS’ full surface in-plane vibration”. 15th international symposium on measurement technology and intelligent instruments (ISMTII 2023).
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件