Influence of scalloping on electrostatic forces in comb drive microdevices

  • V. S. Pawar
  • P. K. Menon
  • A. L. Murty
  • P. Pal
  • A. K. PandeyEmail author
Original Article


Deep reactive-ion etching process is one of the most widely used manufacturing processes for micro-electro-mechanical-system (MEMS) devices, but the main problem with this process is that it leads to undesirable fabrication defects such as slanting, scalloping, etc. In this work, we develop analytical model to capture the effect of scalloping on electrostatic forces in a MEMS-based comb structure. In addition, we also modify the formula to include the parameters related to the size as well as number of scallops. To develop the model, we assume the shape of a scallop as elliptical which is characterized by major axis (2a) and semi-minor axis (b). To validate the model, we compare results with finite element results obtained using Coventerware for single as well as multi-scallops. Subsequently, we discuss the combined effect of scalloping and slanting on electrostatic forces in a comb drive structure. The model presented in the paper may be useful at the design stage of various comb drive MEMS devices such as MEMS gyroscopes.


MEMS Comb drive DRIE Scalloping Electrical forces 



The authors would like to acknowledge partially financial support from Research Centre Imarat (RCI), Hyderabad 500069, India.


  1. Avdeev IV, Lovell MR, Onipede D Jr (2003) Modeling in-plane misalignments in lateral combdrive transducers. J Micromech Microeng 13(6):809CrossRefGoogle Scholar
  2. Ayón Arturo A, Braff R, Chuang-Chia Lin, Sawin Herb H, Schmidt Martin A (1999) Characterization of a time multiplexed inductively coupled plasma etcher. J Electrochem Soc 146(1):339–349CrossRefGoogle Scholar
  3. Kambali PN, Pandey AK (2016) Capacitance and force computation due to direct and fringing effects in MEMS/NEMS arrays. IEEE Sens J 16(2):375–382CrossRefGoogle Scholar
  4. Li J, Zhang QX, Liu AQ, Goh WL, Ahn J (2003) Technique for preventing stiction and notching effect on silicon-on-insulator microstructure. J Vac Sci Technol B Microelectron Nanometer Struct Process Meas Phenom 21(6):2530–2539CrossRefGoogle Scholar
  5. Li J, Liu AQ, Zhang QX (2006) Tolerance analysis for comb-drive actuator using DRIE fabrication. Sens Actuators A Phys 125(2):494–503CrossRefGoogle Scholar
  6. McAuley SA, Ashraf H, Atabo L, Chambers A, Hall S, Hopkins J, Nicholls G (2001) Silicon micromachining using a high-density plasma source. J Phys D Appl Phys 34(18):2769CrossRefGoogle Scholar
  7. Menon PK, Nayak J, Pratap R (2018) Sensitivity analysis of an in-plane MEMS vibratory gyroscope. Microsyst Technol 24(5):2199–2213CrossRefGoogle Scholar
  8. Rebeiz GM (2004) RF MEMS: theory, design, and technology. Wiley, New YorkGoogle Scholar
  9. Singulani AP, Ceric H, Filipovic L, Langer E (April 2013) Impact of bosch scallops dimensions on stress of an open through Silicon Via technology. In: 14th international conference on thermal, mechanical and multi-physics simulation and experiments in microelectronics and microsystems (EuroSimE), Wroclaw, Poland, pp 1–6.
  10. Weinberg MS, Anthony Kourepenis (2006) Error sources in in-plane silicon tuning-fork MEMS gyroscopes. IEEE J Microelectromech Syst 15(3):479–491CrossRefGoogle Scholar
  11. Zarowin CB (1984) Relation between the RF discharge parameters and plasma etch rates, selectivity, and anisotropy. J Vac Sci Technol A Vac Surf Films 2(4):1537–1549CrossRefGoogle Scholar

Copyright information

© Institute of Smart Structures & Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore 2019

Authors and Affiliations

  • V. S. Pawar
    • 1
  • P. K. Menon
    • 2
  • A. L. Murty
    • 2
  • P. Pal
    • 3
  • A. K. Pandey
    • 1
    Email author
  1. 1.Mechanical and Aerospace EngineeringIIT HyderabadKandiIndia
  2. 2.Research Centre ImaratHyderabadIndia
  3. 3.Department of PhysicsIIT HyderabadKandiIndia

Personalised recommendations