Patent ID: 7988816

Claim:
A plasma etching apparatus for etching a predetermined layer of a target substrate by use of plasma of a process gas, the apparatus comprising: a process chamber configured to accommodate the target substrate and including a sidewall connected to ground; a process gas supply system configured to supply the process gas into the process chamber; an exhaust system configured to vacuum-exhaust gas from inside the process chamber; a first electrode and a second electrode disposed opposite each other within the process chamber, the first electrode being an upper electrode, and the second electrode being a lower electrode on which the target substrate is placed; a first radio frequency (RF) power supply connected to the first electrode or second electrode and configured to apply a first RF power thereto for generating the plasma of the process gas between the first and second electrodes; a cooling ring disposed near and around the target substrate on the second electrode to cool an edge of the target substrate; a cooling source built in the second electrode; a heat transfer gas supply system configured to supply a heat transfer gas between the cooling ring and the second electrode; a correction ring disposed around the cooling ring side by side relative to the cooling ring and formed of a conductive ring exposed inside the process chamber; an insulating ring disposed around the correction ring side by side relative to the correction ring; and a direct current (DC) power supply having a negative terminal directly connected to the correction ring and a positive terminal directly connected to a conductive portion connected to ground and insulated from the correction ring and configured to apply a DC voltage thereto, the DC voltage being preset to provide the correction ring with a negative bias, relative to ground potential, for attracting ions in the plasma and to increase temperature of the correction ring to compensate for a decrease in temperature of a space near the edge of the target substrate due to the cooling ring.