| 摘要 |
PURPOSE:To make the exact and sure etching possible, by applying the same light to plasma as is radiated when the chemical species perticipating in the reaction transfer from the excited state to the stable state and detecting the intensity of the incident light and the transmitted light of plasma. CONSTITUTION:The detector 21 constituted of the light source 20, etc. is installed on both sides of the reaction tube 1. The light from the high source 20 is detected by the detector 21 which measures the absorption of the light of plasma in the reaction tube 1. That is, plasma is irradiated by the light whose frequency corresponds to that of the light radiated at the time of etching reaction in which the radical chemical species transfer to the stable state, and the chemical species are again converted into radicals. In this process, some energy of the light is absorbed by plasma. The degree of absorption is large in the process of etching reaction, and becomes smaller with the progress of the etching reaction in the wafer. The detector 21 measures the intensity of the absorption spectrum, and the control equipment 18 stops the RF generating source 14 at the time T0 shown in the graph. |
