Reactive sputter etching of Al in BCl3 |
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Authors: | H.W. Lehmann R. Widmer |
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Affiliation: | Laboratories RCA Ltd., CH-8048 Zurich, Switzerland |
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Abstract: | Etching of Al is studied in pure BCl3 as well as in mixtures with other gases in the reactive sputter etching mode in a cryopumped system. Etch rate, selectivity with respect to positive photoresist, SiO2 and Si and etch profiles are investigated as a function of gas composition, gas pressure, flow rate and plasma power. Plasma chemical processes are monitored by quadrupole mass spectroscopy as well as by optical emission spectroscopy. Perfectly square Al-profiles can be etched if etch rates are kept below 1000 A/min. Al-patterns running over steep steps can also be clearly defined if a certain amount of overetching can be tolerated. The experimental data indicate that the etch process is reactant supply limited. Anisotropic etching is achieved by either a ‘surface inhibitor mechanism’ or the formation of a sidewall protecting film. |
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Keywords: | Dry etching sputter etching VLSI processing |
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