| 摘要 |
PROBLEM TO BE SOLVED: To reliably calculate an atom density of impurities present in generated plasma.SOLUTION: A measurement method of impurities in plasma comprises the steps of: generating plasma using a plasma generation gas; measuring a light emission intensity caused by downward transition from the excitation state of the gas in the plasma, and a light emission intensity caused by downward transition from the excitation state of impurity atoms in the plasma; irradiating the plasma with laser beams, and measuring an intensity of the beam not absorbed by the gas and transmitting through the plasma from among the laser beams and a fluorescence intensity of the gas by laser stimulation; acquiring the density of the gas being downwardly transitioning by using an optical absorption coefficient of the gas calculated from the intensity of the transmitted beam obtained by the measuring step and using the fluorescence intensity of the gas. The measurement method further includes calculating a density of the impurities by using the density and a light emission intensity ratio between the light emission intensity caused by downward transition from the excitation state of the gas and the light emission intensity caused by downward transition from the excitation state of the impurities in the plasma. |
