Process News Summer 2018 | OI Plasma Technology

Ion Beam Nano Patterning: Accurate and Versatile

Author: Dr Sebastien C. R. Pochon, Oxford Instruments Plasma Technology

The need for forming gratings (for example used in VR headsets) or laser diode facets (for optoelectronic devices) in materials such as SiO 2 or InP, respectively, has seen a recent surge in the use of Ion beam etching techniques. Usually ion beam etching is used in semiconductor manufacturing for patterning metal layers such Au, Pt and Ti using a photoresist mask. However selectivity is limited as it is a physical process.

The applications described above requires more control of sidewalls angle and surface roughness, it requires selectivity to the mask be enhanced. Typically gases such as CHF 3 , SF 6 , O 2 and Cl 2 can be added to argon in order to enhance selectivity, Depending on where the gas is injected, it is known as Reactive Ion Beam Etching (RIBE) or Chemically Assisted Ion Beam Etching (CAIBE). The substrate holder (platen) can be tilted between -90°, the loading position, and up to +65°. It provides control over the sidewall profile as well as radial uniformity optimisation. The substrate holder can rotate in order to provide an axisymmetric etch rate profile. A dedicated chiller/heater and helium (conductive medium) are used to transfer heat for cooling/heating during etching. Ion beam directionality in conjunction with variable incident beam angle through platen angle setting enables profile and sidewall control and feature shaping during nanopatterning. Unlike other plasma tools, materials such as SiO 2 and InP can be etched without rotation and at a fixed platen angle allowing gratings or waveguide facets to be etched.

Dr Sebastien Pochon presented his results at SPIE Conference in February 2018. For the extended version of the presentation see:

12 Summer 2018

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