High aspect ratio via etching conditions for deep trench of silicon

Deep trench etching of silicon was investigated as a function of platen power, operational pressure and the SF6:C4F8 gas flow rate. Their effects on the etch rate, etch profile and scallops were also studied. As the platen power was increased from 5 to 30 W, the etch rate was increased from 0.54 to 2.51 μm/min. However, the etch rate was decreased at platen power higher than 30 W. As the pressure was increased from 10 to 25 mTorr, the etch rate was increased from 1.93 to 2.69 μm/min but the etch rate was decreased at the pressure higher than 35 mTorr. As the SF6:C4F8 gas flow rate was increased from 50:50 to 200:160 sccm, the etch rate was increased from 1.91 to 2.31 μm/min and at the SF6:C4F8 gas flow rate of 260:220 sccm, it was decreased to 2.21 μm/min.