Improved Etching Characterstics of Silicone-Oxide by the Enhaned-ICP

초록

We have proposed and developed a novel plasma process technique, named Enhanced-ICP,Which uses periodic on/off control of weak axial magnetic field to provide better uniformity and higher etch rate. The E-ICP process, so far, is considered as a damage-free technique with much improved characteristics. It has already showed better spatial uniformity than 1% and much improved etch rate within a diameter of 10 cm for a photo-resist etch process. As it is necessary to develop this techniqe for other processes also and the etch of SiO2 is important for most of recent semiconductor fabrication, the E-ICP is tested with the CF4 gas plasma. The adoption of E-ICP process for SiO2 etch with CF4 gas also provides better etch profile and etch rate than a normal ICP process at some other specific on/off frequency of weak axial magnetic field than that of oxygen gas. Although this specific frequency characteristics of each gas plasma has been being studied, it is not understood so cleatly yet. The SEM picture reveals that the vertical etch rate increases about 1.3 times larger than that of a normal ICP, while side etch rate does not change noticeably,to provide more vertical slope profile than normal. Furthermore, the comparison of etched bottom profile shows that the E-ICP process achieves no distortion of etched bottom profile, while a normal ICP gives trench-type distortion for a pattern located at the outer position of sample holder.