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6CCVD Research

Development and post-dicing wet release of MEMS magnetometer - an approach

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2021-07-18
JournalMicroelectronics International
AuthorsAditi Aditi, Supriyo Das, Ram Gopal
InstitutionsAcademy of Scientific and Innovative Research, Central Electronics Engineering Research Institute

Abstract

Section titled ā€œAbstractā€

Purpose Si-based micro electro mechanical systems (MEMS) magnetometer does not require specialized magnetic materials avoiding magnetic hysteresis, ease in fabrication and low power consumption. It can be fabricated using the same processes used for gyroscope and accelerometer fabrication. The paper reports the dicing mechanism for the released MEMS xylophone magnetic sensor fabricated using wafer bonding technology and its characterization in ambient pressure and under vacuum conditions. The purpose of this paper is to dice the wafer bonded Si-magnetometer in a cost-effective way without the use of laser dicing and test it for Lorentz force transduction. Design/methodology/approach A xylophone bar MEMS magnetometer using Lorentz force transduction is developed. The fabricated MEMS-based xylophone bars in literature are approximately 500 Āµm. The present work shows the released structure (L = 592 Āµm) fabricated by anodic bonding technique using conducting Si as the structural layer and tested for Lorentz force transduction. The microstructures fabricated at the wafer level are released. Dicing these released structures using conventional diamond blade dicing may damage the structures and reduce the yield. To avoid the problem, positive photoresist S1813 was filled before dicing. The dicing of the wafer, filled with photoresist and later removal of photoresist post dicing, is proposed. Findings The devices realized are stiction free and straight. The dynamic measurements are done using laser Doppler vibrometer to verify the released structure and test its functionality for Lorentz force transduction. The magnetic field is applied using a permanent magnet and Helmholtz coil. Two sensors with quality factors 70 and 238 are tested with resonant frequency 112.38 kHz and 114.38 kHz, respectively. The sensor D2, with Q as 238, shows a mechanical sensitivity of 500 pm/Gauss and theoretical Brownian noise-limited resolution of 53 nT/vHz. Originality/value The methodology and the study will help develop Lorentz force-based MEMS magnetometers such that stiction-free structures are released using wet etch after the mechanical dicing.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2020 - Dual-axis lorentz force MEMS magnetometer
  2. 2017 - Fabrication of MEMS xylophone magnetometer by anodic bonding technique using SOI wafer [Crossref]
  3. 2007 - A resonant micromachined magnetic field sensor [Crossref]
  4. 1996 - A high sensitivity, wide dynamic range magnetometer designed on a xylophone resonator [Crossref]
  5. 2011 - Mechanical design and characterization of a resonant magnetic field microsensor with linear response and high resolution [Crossref]
  6. 2008 - A resonant magnetic field microsensor with high quality factor at atmospheric pressure
  7. 2016 - Recent advances of MEMS resonators for lorentz force based magnetic field sensors: design, applications and challenges [Crossref]
  8. 1998 - Magnetic-field measurements using an integrated resonant magnetic-field sensor [Crossref]
  9. 2008 - A 3D micromechanical compass [Crossref]
  10. 2010 - A xylophone bar magnetometer for micro/pico satellites [Crossref]

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