Dielectric window for plasma processing apparatus, plasma processing apparatus and method for mounting dielectric window for plasma processing apparatus

A dielectric window for a plasma processing apparatus, the dielectric window being provided in the plasma processing apparatus using microwave as a plasma source, and having a substantially circular plate shape and propagating the microwave,

• wherein a first dielectric window recess is formed on an outer region of a surface of the dielectric window in a diametrical direction of the dielectric window at a side where plasma is generated when the dielectric window is mounted in the plasma processing apparatus, the first dielectric window recess is extended in a ring shape and has a tapered shape inwardly in a thickness direction of the dielectric window, and the first dielectric window recess includes an inner tapered surface which is inclined in an upward and outward direction of the dielectric window and an outer tapered surface which is inclined in a downward and outward direction of the dielectric window,
• the first dielectric window recess is formed at a region of the dielectric window where a gas does not pass through,
• a plurality of second dielectric window recesses are formed between a center of the dielectric window and the first dielectric window recess, and each of the second dielectric window recess is recessed inwardly in the thickness direction of the dielectric window from the surface of the dielectric window, and
• the second dielectric window recesses are arranged at a regular interval in a circumferential direction of the dielectric window to have rotation symmetry about the center of the dielectric window in the diametrical direction thereof.

A method for mounting a dielectric window for a plasma processing apparatus in the plasma processing apparatus using microwave as a plasma source, the dielectric window having a substantially circular plate shape and propagating the microwave,

• wherein, in the dielectric window, a first dielectric window recess is formed on an outer region of a surface of the dielectric window in a diametrical direction of the dielectric window at a side where plasma is generated when the dielectric window is mounted in the plasma processing apparatus, and the first dielectric window recess is extended in a ring shape and has a tapered shape inwardly in a thickness direction of the dielectric window,
• wherein a plurality of second dielectric window recesses are formed between a center of the dielectric window and the first dielectric window recess, and each of the second dielectric window recesses is recessed inwardly in the thickness direction of the dielectric window from the surface of the dielectric window,
• wherein the second dielectric window recesses are arranged at a regular interval in a circumferential direction of the dielectric window to have rotation symmetry about the center of the dielectric window in the diametrical direction thereof, and
• wherein the plasma processing apparatus includes a substantially circular plate-shaped slot antenna plate, and the slot antenna plate has a plurality of slots formed through the slot antenna plate in a thickness direction thereof, and the slot antenna plate is disposed above the dielectric window and radiates the microwave toward the dielectric window, and
• the method comprises:
• adjusting a positional relationship between the second dielectric window recesses of the dielectric window and the slots of the slot antenna plate in the circumferential direction when mounting the dielectric window in the plasma processing apparatus.