Anisotropic trench etching of Si using SF6/O2 mixture

This paper presents the etching results of single crystalline silicon using SF₆/O₂ mixture in the traditional RIE work mode of ICP790 system. We investigate the effect of O₂ addition on the etched profile and etch rate at system pressure of 35 mTorr and DC bias voltage of 50 V and the SEM photographs are given. According to these results the anisotropic profile can be achieved at a wide process window by adjusting the O₂ flow rate. The influences of pressure and DC bias voltage on etch rate and parallel shift degree of the trench vertical edge beneath the mask layer are studied and the respective figures are presented also. The etch rate increases with the system pressure at constant DC bias voltage and it also increases with DC bias voltage at constant gas flow rates. All the experiment results are discussed and explained