Plasma Diagnosis In Etching and Ashing of Diamond Carbon Coating

Abstract

Diamond-like carbon (DLC) coating has been widely used as an efficient and reliable protective coating. To recycle the mold-die substrates, the used DLC coating must be perfectly removed before re-coating without damage to substrates and residuals. The RF-DC high dense plasma etching or ashing process is utilized to describe the plasma-etching behavior by using the spectroscopic analysis. First, RF- and DC-voltages together with pressure are varied in this oxygen plasma etching to search for an optimum condition; DC-bias is -450 V, RF voltage is 250 V and oxygen gas pressure 40 Pa. Oxygen plasma spectrum is analyzed to define the pure oxygen plasma. It is composed of oxygen atoms, activated oxygen atoms, and molecules. In-situ plasma monitoring is also used to measure CO peak in the range 200-300 nm. Detection of CO peak proves that carbon in DLC coating is reacted with oxygen flux; i.e. C (in DLC) + O  CO. Variation of CO peaks correspond to etching behavior.