Electrical measurement of undercut in surface micromachining

Somashekara Bhat, Enakshi Bhattacharya

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


In a surface micromachined cantilever the beam thickness, width and the gap get modified during fabrication. Since performance of sensors and actuators strongly depend on the final geometry, it is essential to measure these parameters. Electrical measurements have several advantages over microscopy and we present here two different electrical techniques to measure undercut due to etching. In the resistance based approach, two polysilicon resistors of different length and width are used and the undercut is extracted from the ratio of the measured resistances. In the second technique, resonance frequency is measured for two sets of oxide anchored polysilicon cantilever beams with 20 and 30 um widths. For a given length, the ratio between the measured frequencies for the two widths gives the value of undercut. Measurements are done on both wet and dry etched polysilicon.

Original languageEnglish
Title of host publicationReliability, Packaging, Testing, and Characterization of MEMS/MOEMS VII
Publication statusPublished - 2008
EventReliability, Packaging, Testing, and Characterization of MEMS/MOEMS VII - San Jose, CA, United States
Duration: 21-01-200822-01-2008


ConferenceReliability, Packaging, Testing, and Characterization of MEMS/MOEMS VII
Country/TerritoryUnited States
CitySan Jose, CA

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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