| 摘要 |
PURPOSE:To confirm the time of the completion of etching precisely, by specifically sensing the plasma beam which is characteristically generated during the period while the specific etching reaction is continued, and indentifying the finish of the variation in the generated amount. CONSTITUTION:CF4 is introduced 5 and transformed into plasma by the electric field between an electrode 2 and a water cooled electrode 3. An Si substrate 7 on said electrode 3 is etched. When the reaction is finished, light emission from F radical increases. Photoelectrric conversion 10 is performed via an interference filter 9 whose transmission factor is 50% or more and half value width is 5nm. The output voltage is extracted every 1-5 sec. When the voltage difference in the 3 consecutive points is less than 1mV, it is determined that the reaction is finished. The filter 9 selectively passes only the same wavelength as that of the plasma beam which is characteristically generated and decreased only during the period while the reaction is continued. The filter 9 is formed by multilayer films of metal or nonmetal. In this constitution, the time of the completion of the plasma etching can be automatically sensed conveniently and very accurately. |
