A plasma processing device member according to the disclosure includes a base material and a film formed of an oxide, or fluoride, or oxyfluoride, or nitride of a rare-earth element, the film being disposed on at least part of the base material, the film including a surface to be exposed to plasma, the surface having an area occupancy of open pores of 8% by area or more, and an average diameter of open pores of 8 m or less.

Methods comprise performing two or more thermal cycles on an article comprising a body and a ceramic coating. Each thermal cycle of the two or more thermal cycles comprise heating the ceramic article to a target temperature at a first ramping rate. Each thermal cycle further comprises maintaining the article at the target temperature for a first duration of time and then cooling the article to a second target temperature at a second ramping rate. The method further comprises submerging the article in a bath for a second duration of time to remove the particles from the ceramic coating.

Methods comprise performing two or more thermal cycles on an article comprising a body and a ceramic coating. Each thermal cycle of the two or more thermal cycles comprise heating the ceramic article to a target temperature at a first ramping rate. Each thermal cycle further comprises maintaining the article at the target temperature for a first duration of time and then cooling the article to a second target temperature at a second ramping rate. The method further comprises submerging the article in a bath for a second duration of time to remove the particles from the ceramic coating.

A structure includes a polycrystalline substance of yttrium fluoride, wherein an average crystallite size in the polycrystalline substance is less than 100 nanometers. When taking a peak intensity detected near diffraction angle 2=24.3 by X-ray diffraction as , and taking a peak intensity detected near diffraction angle 2=25.7 as , a peak intensity ratio / of the structure is not less than 0% and less than 100%.

A structure includes a polycrystalline substance of yttrium fluoride, wherein an average crystallite size in the polycrystalline substance is less than 100 nanometers. When taking a peak intensity detected near diffraction angle 2=24.3 by X-ray diffraction as , and taking a peak intensity detected near diffraction angle 2=25.7 as , a peak intensity ratio / of the structure is not less than 0% and less than 100%.

A method for conditioning a ceramic layer with a thickness of less than 150 m over a substrate is provided. The ceramic layer is cleaned. A region of the ceramic layer is scanned with a pulsed excimer laser beam at a repetition rate of 3-300 Hz.

A method for conditioning a ceramic layer with a thickness of less than 150 m over a substrate is provided. The ceramic layer is cleaned. A region of the ceramic layer is scanned with a pulsed excimer laser beam at a repetition rate of 3-300 Hz.

A coating material containing an oxyfluoride of yttrium and having a Fisher diameter of 1.0 to 10 m and a tap density TD to apparent density AD ratio, TD/AD, of 1.6 to 3.5. The coating material preferably has a pore volume of pores with a diameter of 100 m or smaller of 1.0 cm.sup.3/g or less as measured by mercury intrusion porosimetry. A coating containing an oxyfluoride of yttrium and having a Vickers hardness of 200 HV0.01 or higher. The coating preferably has a fracture toughness of 1.010.sup.2 Pa.Math.m.sup.1/2 or higher.

A coating material containing an oxyfluoride of yttrium and having a Fisher diameter of 1.0 to 10 m and a tap density TD to apparent density AD ratio, TD/AD, of 1.6 to 3.5. The coating material preferably has a pore volume of pores with a diameter of 100 m or smaller of 1.0 cm.sup.3/g or less as measured by mercury intrusion porosimetry. A coating containing an oxyfluoride of yttrium and having a Vickers hardness of 200 HV0.01 or higher. The coating preferably has a fracture toughness of 1.010.sup.2 Pa.Math.m.sup.1/2 or higher.

Methods comprise performing two or more thermal cycles on an article comprising a body and a ceramic coating. Each thermal cycle of the two or more thermal cycles comprise heating the ceramic article to a target temperature at a first ramping rate. Each thermal cycle further comprises maintaining the article at the target temperature for a first duration of time and then cooling the article to a second target temperature at a second ramping rate. The method further comprises submerging the article in a bath for a second duration of time to remove the particles from the ceramic coating.