Design and fabrication of air-bridge CPW using porous silicon and MEMS technology

Young Min Kim, Jong Hyun Lee, Seong Ho Kong, Kwang Man Lee

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


This paper proposes a three-dimensional structure for an RF passive device using a thick oxidized porous silicon layer (OPSL). The OPS air-bridge was fabricated using an anodic reaction, reactive ion etching (RIE), tetramethyl ammonium hydroxide (TMAH) etching, and a multistep oxidation process. The problem of the high dielectric loss of a waveguide on silicon can be solved using a thick OPS air-bridge. The three dimensional structures were fabricated using a 20 wt.% TMAH solution at 80°C for 3 h, and the thickness of the micromachined OPS air-bridge was 10 μm. A coplanar waveguide (CPW) structure was also fabricated on the OPSL air-bridge for RF application. The fabricated structure was 2 mm in length, and the width of the signal line and the gap between the ground and the signal lines were 100 μm and 20 μm, respectively. This process is well compatible with conventional complementary metal oxide semiconductor (CMOS) fabrication process without post-processing, and does not require an additional mask for silicon etching.

Original languageEnglish
Pages (from-to)289-298
Number of pages10
JournalSensors and Materials
Issue number5
StatePublished - 2005


  • Air-bridge structure
  • Coplanar waveguide
  • Multistep oxidation process
  • Porous silicon micromachining
  • TMAH etching


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