Dry micromachining of high aspect ratio Si for microsensors

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)234-243
Journal / PublicationProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 1995
Externally publishedYes


TitleMicromachining and Microfabrication Process Technology
PlaceUnited States
CityAustin, TX
Period23 - 24 October 1995


Dry micromachining technology is developed for fabricating high aspect ratio Si structures for microsensors. Two microsensor structures, including Si resonators and field emitters, will be presented in this paper. Released Si resonators up to 30 μm deep with 2 μm wide gap were fabricated. This is accomplished by a novel deep etch and shallow diffusion technique. High aspect ratio Si microstructures with vertical profile were first etched using an electron cyclotron resonance source, followed by a shallow B diffusion to fully convert the etched microstructures to p++ layer. In addition, dry etching was used to form Si emitters with sharp tips and high packing density. Profile for Si emitters is controlled by erosion of the SiO2 mask during dry etching. The ion flux and energy, controlled through coupled microwave and rf power, were used to obtain the desired etch rate and basewidth of the emitters. By increasing the pressure during etching, more vertical Si emitters were developed. Sharp emitter tips in Si with 2.2 μm basewidth and 11 μm height were fabricated and packing densities up to 1×107 tip/cm2 were achieved.

Research Area(s)

  • Dry etching, Electron cyclotron resonance, Field emitters, High aspect ratio Si, Mask erosion, Micromachining, Resonators, Shallow diffusion