Shower head structure and plasma processing apparatus using the same

A shower head structure, comprising:

• a plate body having a first surface and a second surface opposite to the first surface, the plate body comprising a first zone and a second zone, wherein gas flows through the plate body from the first surface toward the second surface during operation, the first zone is surrounded by the second zone, and an amount of gas flow through the plate body in the first zone per unit area is substantially equal to an amount of gas flow through the plate body in the second zone per unit area;
• a plurality of first holes open at the first surface and in the first zone;
• a plurality of second holes open at the first surface and in the second zone;
• a plurality of third holes open at the second surface, in the first zone, and each of the third holes being in connection with each of the first holes;
• and
• a plurality of fourth holes open at the second surface, in the second zone, and each of the fourth holes being in connection with each of the second holes;
• wherein a diameter of each of the second holes is less than 2 times of a thickness of a Debye sheath layer.

A plasma processing apparatus, comprising:

• a chamber;
• a radio frequency (RF) power source coupled to the chamber;
• a shower head in the chamber and coupled to the RF power source, wherein the shower head is configured to provide a uniform amount of gas flow per unit area across the entire shower head;
• and
• a susceptor below the shower head, and a first surface of the shower head facing the susceptor;
• wherein the first surface of the shower head having a plurality of first through holes in a first zone, and a plurality of second through holes in a second zone, the first zone is surrounded by the second zone, an amount of gas flow through the plate body in the first zone per unit area is substantially equal to an amount of gas flow through the plate body in the second zone per unit area during operation, and a second diameter of each of the second through holes is less than 2 times of a thickness of a Debye sheath layer.