Silicon surfaces which had been exposed to CF4/40%H2 reactive ion etching have been characterized by x‐ray photoelectron emission spectroscopy, He ion channeling, H profiling, and Raman scattering techniques. Plasma exposure of a clean Si surface leads to the deposition of a thin (∼30–50Å thick) C,F containing film. The near‐surface region (∼30–50Å) of the Si substrate is heavily disordered (“amorphized”), as found by ion channeling and Raman scattering. A modified, less damaged Si region extends from about 30–50Å from the surface to a depth in excess of 250Å. This layer contains a high concentration (∼5 atom percent) of H as shown by hydrogen profiling techniques. From the observation of Si‐H and normalSi‐H2 vibrational modes by Raman scattering, it has been shown that the H is bonded to the Si lattice. In ion scattering, the extended modified Si layer appears to cause a strongly enhanced background in the energy spectra. Results of Monte Carlo range calculations are reported and compared with the damage depth found experimentally.

Silicon surfaces which had been exposed to a CF4 /H2 plasma have been characterized by x-ray photoelectron spectroscopy, ellipsometry, He ion channeling, and H profiling techniques. Plasma exposure leads to the deposition of a thin (∼30 Å thick) C,F-polymeric layer. Hydrogen and/or damage (displaced Si atoms) can be detected in the near-surface region up to a depth in excess of 400 Å from the Si surface.

Highly selective etching of SiO2 with respect to silicon and resist is obtained by reactive ion etching in CF4+H2 . The maximum etch rate ratio depends in a sensitive way on gas residence time with etch rate ratio increasing with decreasing residence time. The reproducibility of high etch rate ratios was found to decrease with increasing pressure. The cleanliness of etching is determined by the material of the electrode and the electrode to wall area ratio. A process was developed by optimizing etching conditions and reactor design and then was tested electrically. Contact holes were etched to 0.25 μm junctions using full RIE in CF4+H2 and buffered HF . The same low junction leakage and contact resistivity, 10−9 amps/cm2and 10−6 Ω‐cm2, were measured for both. Implications for scaling CF4+H2 RIE into larger etching reactors as well as its use to pattern features at 1 μm ground rules are discussed.

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