TiN Etching and Its Effects on Tungsten Etching in SF₆/Ar Helicon Plasma

Etching characteristics of TiN film have been investigated in SF6/Ar helicon plasma. The etch rate of TiN film increases with increasing source power, bias power and temperature, exhibits a maximum at a moderate pressure as a function of pressure. A possible mechanism of titanium fluoride formation is proposed based on the results of optical emission spectroscopy (OES). In order to determine the effect of titanium fluorides on tungsten etching, the loading effect in tungsten etchback is investigated as a function of source power, bias power and temperature. Using secondary ion mass spectrometry (SIMS), the relative concentrations of titanium fluorides redeposited on tungsten are measured by varying the bias power and temperature. The loading effect is reduced by enhancing the redeposition of titanium fluorides on a tungsten plug with increasing source and bias power. The loading effect is also retarded by lowering the temperature.