| 摘要 |
PURPOSE:To increase an etching speed and to make etching uniform substantially, by providing a screw around a sample holder, as well as a photodetector monitoring the thickness of a sample automatically. CONSTITUTION:Owing to the presence of a screw 21 provided on the peripheral surface of a sample holder 11, the initial elliptical rotation of the sample holder 11 is adjusted automatically to the uniaxial as the holder 11 rotates, and thereby a convection of a mixture liquid is generated. Moreover, a light-emitting diode (LED)22 and a light-receiving element 23, which operate as a photodetector, are provided in the lower part of a rotary holder 2, and said light-receiving element 23 receives a light emitted from LED22 and reflected by a wafer 10. As the result, the thickness at the time of etching is monitored according to the intensity of the reflected light. Furthermore, a shower 24 jetting an acetic acid is provided in the upper part of a vessel 1. When the thickness of a sample 10 turns to be 3,000Angstrom , for instance, the acetic acid is jetted from the shower 24 so as for the mixture ratio in the vessel 1 to be changed, and thereby an etching speed is reduced. |
