| 摘要 |
PURPOSE:To eliminate the influence of contamination of a substance to be etched by introducing an infrared light of a predetermined wavelength to the surface of a semiconductor substrate of the side not formed with a thin metal film of the surface of the substrate, measuring the intensity of the light reflected on the thin film through the substrate of the infrared light, and obtaining the etching end point by the intensity of the reflected light to readily position a detector, thereby improving S/N ratio. CONSTITUTION:The infrared light of 1.3mum of wavelength modulated by a sinusoidal wave of 1kHz from an infrared light emitting unit 5 is passed through a half mirror 4 to an optical fiber 1, and emitted to a silicon substrate 10 formed with the thin metal film as parallel beam via a rod lens 3. Part of the infrared light of 1.3mum of wavelength is reflected on the back surface of the substrate 10, but is passed through the Si, reflected on the metal film surface, again through the lens 3, and returned to the optical fiber 1. The returned infrared light is reflected on the half mirror 4, and detected by an infrared light detector 6. When the metal film is etched and removed by the plasma, the reflected light is erased from the metal film, thereby notifying the etching end point.
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