| 摘要 |
PURPOSE:To detect the progression condition and end point of etching easily by taking out only the emission spectrum by a material to be etched from the observed emission spectra of an etching system. CONSTITUTION:After light from an etching vessel 2 is passed through a chopper 7, it is bisected with a half mirror 14, and is introduced into two units of different spectroscopes 8, 8'. At this time, the difference between the signal S1 from a photodetector 9 and the signal S2 from a photodetector 9' is taken, whereby the unstability of the background signal accompanied with the plasma fluctuation in the vessel 2 is eliminated and only the emission spectrum specific to a material 4 to be etched can be taken out. Only this spectrum is recorded in a recorder 11. In this case, the wavelength of the spectroscope 8 is set at the emission wavelength specific to the material 4 and the wavelength of the spectroscope 8' is set at the wavelength as near the emission spectrum specific to the material 4 as possible without having its influence. |
