| 摘要 |
PURPOSE:To detect an etching terminal point from the change in scattering strength of a monochromatic ray, by performing etching under a monochromatic ray irradiation. CONSTITUTION:Polycrystalline Si is put onto a thermal oxide film on an Si substrate, and CF4 gas is introduced for plasma etching. In parallel with this etching the following method is performed wherein Ar laser beam 5 is applied to a desired region on the etching surface, whose scattered ray 7 and plasma light between electrodes are conducted through an optical fiber 8, and only the scattered beam of the laser is separated by an interference filter 9 and passed through a photo diode 10 to detect the change of the strength by a detector 11. The scattering strength of the polycrystalline Si layer is high, while that of an SiO2 layer of fine crystallization is remarkably low in comparison there with it. This permits exact detection of an etching terminal point. |
