| 摘要 |
PROBLEM TO BE SOLVED: To detect the end point of etching through a simple arrangement even if the reflectivity is substantially constant before and after etching and no bubble is generated during etching. SOLUTION: A substrate 30 where a hydrophilic film is applied onto a water repellent substance is rotated while spraying etching aqueous solution 35a thereto and then spraying and rotation are stopped. The substrate 30 is then irradiated with a light beam from a light source 41 and reflected light is detected by a photodetector 42. When the substrate is exposed by etching, the liquid is changed into particulate state by a 'coating' of etching aqueous solution and water repellency of the substrate and surface tension of the liquid and the reflected light is disturbed. A circuit 43 amplifies and differentiates an output from the photodetector 42 and then compares it with a reference voltage thus detecting the end point of etching. In response to the detection, etching liquid 35a is ejected from a nozzle 39 under a state where the nozzle 39 is moved to the substrate 30 side and the substrate 30 is rotated. Etching is stopped upon elapsing a set time after detecting the end point of etching. |
