SIO2 ETCHING CHARACTERISTICS USING UHF PLASMA SOURCE

The characteristics of the UHF (Ultra-High-Frequency) plasma and SiO2 etching with this plasma source were investigated. A study on the opti cal emission spectroscopy shows that the plasma abounded in CF2 radica ls, which indicates that the degree of the dissociation of feed gas is low. The ion saturation current density shows low dependence on press ure. The etching characteristics, such as SiO2 etch rate and RIE lag, also show low dependence on pressure. There is no significant effect o f pressure on etched profile for a given ion saturation current densit y, a self-bias voltage and a selectivity of SiO2 to Photoresist (PR). These characteristics demonstrate that the UHF plasma source can be ex pected to provide a wide process window for pressure.