METHOD OF SETTING THICKNESS OF DIELECTRIC, AND SUBSTRATE PROCESSING APPARATUS WITH DIELECTRIC PROVIDED ON ELECTRODE

PROBLEM TO BE SOLVED: To provide a method of setting the thickness of a dielectric provided on an electrode, which enables the suppression of wear of the dielectric when plasma-etching a silicon dioxide film on a substrate.SOLUTION: The substrate processing apparatus for plasma-etching a silicon dioxide film formed on a wafer W has a susceptor 12, an upper electrode 24 opposed to the susceptor 12, and a dielectric 26 made of silicon dioxide and provided on the upper electrode 24. In the apparatus, a potential of plasma that the dielectric 26 faces in the case when the upper electrode 24 does not have the dielectric 26 provided thereon is estimated based on an electric power value of bias power applied to the susceptor 12 and A/C ratio in a chamber 11. The thickness of the dielectric 26 is set so that the plasma potential obtained by multiplying the estimated plasma potential by the capacitance reduction ratio of when the capacitance of the dielectric 26 is combined with that of a sheath arising in the vicinity of the surface of the dielectric 26 is equal to or less than 100 eV.