| 摘要 |
A dry etching method for etching an SiO2 based material layer with a high etchrate, high selectivity, low damage, and pollution is disclosed. An etching gas containing a high-order fluorocarbon compound and an oxyhalogen compound is used. A main etchant is CFX+dissociated in a large amount from the high-order fluorocarbon compound. On the other hand, the oxyhalogen compound, which has in a molecule one polarity functional group selected from carbonyl, thionyl, sulfuryl, nitrosyl, and nitryl, has the following effects: (1) a reduction in a deposit amount of carbonaceous polymer necessary for securing selectivity, by increasing chemical bond intensity, polymerization degree, and polarity of carbonaceous polymer derived from decomposition products of a resist mask; and (2) an increase in the etchrate by extracting O atoms from SiO2 by reducive radicals such as SO* and NO* derived from the polarity functional group. For improving selectivity to an Si based underlying layer, it is effective to increase the content ratio of the oxyhalogen compound in an overetching process, or to use a sulfur based compound as well which is capable of producing a sulfur based deposit such as S2 F2.
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