PARAMETRIC MODELING AND MEASUREMENT OF SILICON ETCHING IN A HIGH DENSITY CHLORINE PLASMA

The plasma parameter scaling of silicon etching in a high density chlorine discharge has been measured and described by an ion assisted etch model. The measurements were performed in an electron cyclotron resonance chlorine plasma at pressures between 0.5 and 4.0 mTorr. When the Cl neutral atom flux to the wafer is sufficiently high, the etch rate is controlled by the ion power flux to the substrate, JiVs, where Ji is the ion current density and Vs is the plasma sheath potential. There is a threshold value of the ion power flux below which no etching occurs. When the Cl flux is low, the etch rate is controlled by the limited supply of Cl atoms and is approximately independent of the ion power flux.