Substrate treating apparatus and substrate support unit

An apparatus for treating a substrate, the apparatus comprising:

• a chamber having a process space inside;
• a support unit configured to support the substrate in the process space;
• a gas supply unit configured to supply gas into the process space;
• and
• a plasma source configured to generate plasma from the gas,
• wherein the support unit comprises:
• a dielectric plate on which the substrate is placed;
• a lower electrode disposed under the dielectric plate, the lower electrode having a first diameter;
• a power supply rod configured to apply RF power to the lower electrode, the power supply rod having a second diameter;
• and
• a ground member disposed under the lower electrode and spaced apart from the lower electrode by a first gap, the ground member including a plate portion having a through-hole formed therein through which the power supply rod passes, the through-hole having a third diameter,
• wherein the first gap increases farther away from the power supply rod.