| 摘要 |
PURPOSE:To detect exactly the etching finishing time when an Al layer on the semiconductor substrate is to be etched by dry etching according to plasma by a method wherein an optical filter, an optoelectric transducer, an AC-DC converter, a memory circuit, etc., are provided in the device, and the specified wave length light intensity before the starting of etching and light intensity at the middle of etching are compared. CONSTITUTION:Light 1 emitted from plasma is applied to the optical filter 2 to permeate light of the specified wave length, which is the spectrum of the Al substrate intending to etch, and light 3 permeated therein is inputted to the optoelectric transducer 4. Then output transduced into an electric signal according thereto is amplified by an amplifier 5, output thereof is applied to the finishing point in time detecting circuit 6, while output thereof is recorded also in a recorder 7. After then, a finishing point in time detecting signal 8 is outputted from the circuit 6. At this construction, the circuit 6 is constructed of the AC-DC converter 10, the memory circuit 11, a comparator 12, a timer 13 and a control circuit 14, and when intensity of light generated in the substrate becomes to the lowest, it is judged as the finishing time. |
