| 摘要 |
PROBLEM TO BE SOLVED: To provide a wear-out amount measuring method capable of measuring wear-out amount of a consumable member, at desired occasions.SOLUTION: When measuring wear-out amount of a focus ring 25, containing an upper surface 25a exposed to plasma and a lower surface 25b, faces a susceptor, a reference piece 57 containing a lower surface 57b facing the susceptor and an upper surface 57a facing the focus ring 25 are thermally connected to the focus ring 25. By irradiating a low-coherence light beam to the focus ring 25 which is vertical with respect to the upper surface 25a and the lower surface 25b, a first optical path length of the low-coherence light that reciprocates along the thickness direction inside the focus ring 25 is measured. By having the low-coherence light beam irradiated to the reference piece 57 which is vertical with respect to the upper surface 57a and the lower surface 57b, a second optical path length of the low-coherence light that reciprocates along thickness direction in the reference piece 57 is measured. Based on the ratio between the first optical path length and the second optical path length, the worn-out amount of the focus ring 25 is calculated. |
