| 摘要 |
PROBLEM TO BE SOLVED: To detect the endpoint of plasma treatment in a stable and highly precise manner, by a method wherein a signal component is extracted in accordance with the progress of plasma treatment, and the end point of plasma treatment is detected, based on the change of the extracted signal component. SOLUTION: A sampling signal 72 is generated in a sampling signal generating circuit 69, based on the high frequency signal sent from a signal generator 37. The phase of the sampling signal 72 is adjusted in the desired amount, in accordance with the waveform of emitted light by a phase shifter 65. More specifically, the phase of the sampling signal 72 is adjusted so that the high peak component, which greatly changes when the end point is detected, is sampled. Subsequently, the sampling signal is sent to a signal treatment circuit 56, the high peak, which changes greatly at the endpoint, is selectively detected and outputted. This output signal is sent to a low-pass filter 57, and a light- emitting signal is obtained. The time when signal intensity is suddenly attenuates is the end point of etching. The accuracy of detection of the end point for etching a microscopic pattern can be enhanced through this method. |
