Effect of C:F deposition on SiCOH etching in a CHF_3 dual-frequency capacitivelycouple plasma, driven by a high-frequency source of 60 MHz (HF) and a low-frequency source of2 MHz (LF) simultaneously, is investigated. With the increase in LF power, the change of C:Flayer from dense C:F layer to porous C:F layer and further to C:F filling gaps was observed, whichled to the transition from films deposition to films etching. The change of C:F layer is relatedto the bombardment by energetic ions and CF_2 concentration in the plasma. As the LF powerincreased to 35～40 W, the energetic ions and the low CF_2 concentration led to a suppression ofC:F deposition. Therefore, the SiCOH films can be etched at higher LF power. Effect of C: F deposition on SiCOH etching in a CHF_3 dual-frequency capacitively coupled plasma, driven by a high-frequency source of 60 MHz (HF) and a low-frequency source of 2 MHz (LF) simultaneously, is investigated. in LF power, the change of C: Flayer from dense C: F layer to porous C: F layer and porous to C: F filling and further to C: F filling gaps was observed, which led to the transition from film deposition to film etching. The change of C: F As the LF power iscreased to 35-40 W, the energetic ions and the low CF 2 concentration led to a suppression of C: F deposition. Therefore, the SiCOH films can be etched at higher LF power.