Low-temperature electron-cyclotron-resonance microwave plasma etching and reactive ion etching are described for ULSI device fabrication. Highly selective anisotropic etching at a high rate, which implies dry etching without tradeoffs, is performed without changing the discharge parameters. This etching is only achieved at reduced wafer temperatures. The etching mechanism and the model are discussed based on the etching yield results obtained by the mass-selected reactive ion beam etching experiments. The new etching system and the etching properties obtained for the low-temperature etching are reviewed comparing those obtained in the conventional reactive ion etching and electron-cyclotron-resonance microwave plasma etching.

Polymer deposition on Si and SiO2 surfaces has been investigated in CH2F2, CHF3, CF4, and CHClF2 gas plasmas, using a microwave plasma etching system. The dependence of the deposition rate on gas pressure, RF bias power, and substrate temperature was measured at a temperature between -120°C and 150°C. The deposition rate increased with decreasing temperature in CH2F2, CHF3, and CHClF2 plasmas. The deposition of polymers occured only below -60°C in the CF4 plasma. The obtained dependence of the deposition rate on gas pressure was examined in terms of the volume of adsorbed particles. X-ray photoelectron spectroscopy measurement showed that the number of bondings between C and F atoms in deposited polymers increases with decreasing temperature and RF power, and increasing gas pressure.

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