The reactive ion etching (RIE) of quartz and of silica-based glasses (Suprasil 2, Herasil 2, BK7, LE, NA and soda-lime) has been examined in CF 4 /CHF 3 plasmas. The etch rate was shown to reduce strongly with an increasing percentage of non-volatile elements in the glass. The etching of the quartz and the Suprasil 2 and Herasil 2 glasses was consistent with a process of ion-enhanced chemical reaction as identified by Steinbruchel 1 . For these substrates, the etch rate was directly dependent on the square root of bias voltage in the RIE and increased with the ratio of CF 4 :CHF 3 in the gas mixture. The comparatively low etch rates of the LE (low expansion), soda-lime and NA (non-alkali) glasses were equivalent in both the CHF 3 /CF 4 and Ar plasmas, indicating a process of sputter etching. The BK7 glass has shown intermediate characteristics with a higher etch rate in CF 4 /CHF 3 than in Ar plasma, indicating ion enhanced chemical etching but with little dependence on the CF 4 :CHF 3 gas ratio. These results have been applied in the fabrication of grating patterns.