Method for detecting end point in plasma etching by impedance change

摘要

A method for detecting end-point in a plasma etching process by monitoring plasma impedance changes on a time scale is disclosed. In the method, a plasma etching process is first conducted in a process chamber, while changes in a parameter of plasma impedance in the chamber occurring during the etching process is recorded in a curve on a time scale. An end-point of the plasma etching process is then defined for the etching of a specific material layer at a point where the direction of a slope of the curve changes.