A method for trimming a carbon-containing film includes: (i) providing a substrate having a carbon-containing film formed thereon; (ii) supplying a trimming gas and a
rare gas to the reaction space, which trimming gas includes an
oxygen-containing gas; and (iii) applying RF power between the electrodes to generate a
plasma using the trimming gas and the
rare gas and to thereby trim the carbon-containing film while controlling a trimming rate at 55 nm / min or less as a function of at least one parameter selected from the group consisting of a flow rate of an
oxygen-containing gas, a flow rate of
nitrogen-containing gas to be added to the
oxygen-containing gas, pressure in the reaction space, RF power, a
duty cycle of RF power, a distance between the electrodes, and a temperature of a
susceptor on which the substrate is placed.