| 主权项 |
1. A plasma etching method for etching a substrate using a processing gas converted into plasma, the plasma etching method comprising:
a holding step of holding the substrate with a holding unit arranged within a processing chamber; a processing gas supplying step of supplying processing gas to a space between the holding unit and an electrode plate facing the holding unit within the processing chamber, the processing gas being supplied from a plurality of supply parts arranged at different positions with respect to a radial direction of the substrate; and a high frequency power supplying step of converting the processing gas supplied to the space from the plurality of supply parts into plasma by supplying a high frequency power from a high frequency power supply to at least one of the holding unit and the electrode plate; wherein the processing gas supplying step includes controlling an adjustment unit configured to adjust a supply condition for supplying processing gas with respect to each of the plurality of supply parts such that the supply condition that is adjusted varies between a first position and a second position, the first position being where an effect of diffusion of supplied processing gas is greater than an effect of flow of supplied processing gas on an active species concentration distribution of active species contained in the plasma-converted processing gas at the substrate, and the second position being where the effect of flow of supplied processing gas is greater than the effect of diffusion of supplied processing gas on the active species concentration distribution at the substrate, wherein the plurality of supply parts include a first supply part for supplying processing gas to a center portion toward a radial center of the substrate and a second supply part for supplying processing gas to a substrate portion toward a radial periphery of the substrate with respect to the center portion, and wherein in the processing gas supplying step, assuming u denotes a processing gas flow rate and D denotes a processing gas diffusion coefficient at the substrate portion where the processing gas is supplied from the second supply part, and L denotes a distance between the holding unit and the electrode plate, the adjustment unit is configured to adjust the supply condition of the processing gas based on a determination whether a Peclet number calculated by uL/D is less than one in a part of the substrate where the processing gas is supplied. |
