| 摘要 |
PURPOSE:To detect the end point of etching with high accuracy by starting the operation of detection at a point of time when the amount of plasma light is brought to a stationary state, detecting a tendency in which the amount of plasma light begins to decrease or increase, and detecting the end point of etching. CONSTITUTION:The operation of detection is started at a point of time when the amount of plasma light is brought to a fixed amount or the amount of a monotonous change after starting a reaction. A tendency in which the amount of plasma light begins to decrease or increase at the same time as the reaction is completed is detected, and the end point of etching is detected. The computation of a secondary differential value is started when the time when the amount of plasma light is brought to the amount of the monotonous change or a fixed amount after starting the reaction passes. A reaching to either decision value in positive and negative decision values regarding the completion of the reaction previously set of the secondary differential value is detected, and a reaching to another decision value of the secondary differential value is detected, thus detecting the end point of etching. According to the method, the end point of etching can be detected with high accuracy even when the curve of the change of a reaction time regarding the amount of plasma light is brought to any curve. |
