Plasma Etching

Due to the silicon in its backbone, CYCLOTENE* resins cannot be etched in pure oxygen but rather require fluorinated etchant gases such as CF₄, SF₆ or NF₃. Typical etch gas compositions include 80:20 O₂/CF₄ and 90:10 O₂/SF₆. Etch rates are highly dependent on the concentration of fluorine gas, the etching mode (isotropic plasma or RIE), the tool used and the input parameters such as power, pressure, and flow rate. SiO₂ residue has been identified when the fluorine concentration is too low.

Hard Masking: A variety of metal or inorganic (SiO₂) masks can be used. Typical mask thickness for RIE processing is 0.3 to 0.5 µm.

Soft Masking: AZP 4620 photoresist shows a 0.7 BCB/resist selectivity at an etch rate of 0.7 µm/min when etched in a 9:1 O₂/CF₄ plasma.

Soft Mask Etching of CYCLOTENE 3022 Resin Using AZP4620 Photoresist [Ref:1994-20]

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