Dry Etching Cluster (DRIE)

KNMF Laboratory for Micro- and Nanostructuring

Our Dry Etching Cluster consists of the Oxford RIE Plasmalab System 100 with ICP 380 source and the Oxford RIBE Ionfab 300. (RIE: Reactive Ion Etching, ICP: Inductively Coupled Plasma, RIBE: Reactive Ion Beam Etching). The Dry Etching Cluster is an advanced tool for micro- and nanomachining of various materials. The basic feature is a high frequency generator (RF) working at 13.56 Mhz, combined with a high vacuum chamber for wafers with a diameter of 4”. The power varies in the range of 1-2500 W. Available process gases are SF6 and O2 for silicon etching; Cl2, He, Ar and O2 for chromium and other metals.

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Details (DRIE)


  • Silicon etching via the cryo process (process temperatures are between -80 and -150 °C)
  • Production of highly vertical, highly parallel and smooth sidewalls
  • Critical lateral dimensions down to the range of 100 nm
  • Aspect ratios (ARs) up to 6 are possible.
  • Laser end point detection
  • Metal etching via RIBE



  • Min. lateral dimensions: 100 nm
  • Min. depth: 50 nm
  • Max. aspect ratio at critical dimensions: 4
  • Total max. depth: 40 µm


  • Min. dimensions in lateral: 100 nm
  • Selectivity over resist: 1:1
  • Etch rate: 25…35 nm/min


  • Mask material: PMMA, SiO2, ma-N 2401
  • Structures on Si fragments or complete 4” Si wafers

Notice: Only silicon and chromium substrates can be processed reproducibly with standard processes at the moment.

Design rules

  • Explicit and unambiguous layout according to the mentioned limitations.
  • Markers for the better localization of the structures, e.g. in the SEM
  • If the micro/nano structure is already written onto the substrate, the mask material has to be PMMA, SiO2 or ma-N 2401
  • If combined with the KNMF e-beam, specific limitations concerning the e-beam design rules have to be considered

Typical structures and designs

Figure 1

Fig. 1: Deep etched silicon gratings


Figure 2

Fig. 2: Silicon nanopillars with high aspect ratio


Figure 3

Fig. 3: Freestanding cantilevers in silicon


Figure 4

Fig. 4: Cantilever structures in chromium