| 摘要 |
PURPOSE: To determine termination of an etching simply and highly accurately by determining the buildup value of the luminous intensity waveform of a plasma, and by so adjusting the sampling time interval of the luminous intensity of the plasma in the termination region of the etching as to increase the peak value of the secondary derivative of the luminous intensity of the plasma. CONSTITUTION: The value of a luminous intensity I of a plasma after a time t1 elapses from the initial time of an etching is determined. That is, by setting the reference value of the luminous intensity I of a plasma to I1 for a product having a wide area, and by setting its reference value to I2 for a product having a narrow area, whether the value of the luminous intensity I of the plasma is larger than I1 and whether its value is smaller than I2 are determined respectively. Then, when the value of the luminous intensity I of the plasma is determined as I>I1, the value of a difference Δt when subjecting it to a secondary differentiation is so set as to be come small. That is, its sampling time interval Δt used in the numerical operation of its secondary differentiation is so set as to become small.
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