For further scaling down of the silicon devices, the application of low dielectric constant materials instead of silicon oxide has been considered to reduce power consumption, crosstalk, and interconnection delay. In this paper, the effect of O 2 /SF 6 plasma chemistry on the etching characteristics of polyimide-one of the promising low-k interlayer dielectrics-has been studied. The etch rate of polyimide decreases with the addition of SF 6 gas due to formation of nonvolatile fluorine compounds inhibiting reaction between oxygen and hydrocarbon polymer, while applying substrate bias enhances etching process through physical attack. However, addition of small amount of SF 6 is desirable for etching topography. SiO 2 hard mask for polyimide etching is effective under O 2 plasma etching(selectivity~30), while O 2 /SF 6 chemistry degrades etching selectivity down to 4. Based on the above results, 1?2μm L&S PI2610 patterns were successfully etched.