Balanced electron drift oxide etcher with Xe added gas chemistry for low cost and high performance contact metallization

A new plasma source called balanced electron drift (BED) magnetron plasma was developed for SiO₂ contact/via hole etching. E×B drift of electrons, which is notorious for degrading the uniformity of magnetron plasmas, has been completely balanced by applying appropriate 100 MHz rf power to the upper ring electrode. As a result, highly uniform self bias voltage (ΔV_dc<4 V) and ion flux (ΔJ_ion<±3%) profiles were obtained on 200mm wafer. BED etcher has additional benefit of reducing dopant deactivation in the Si substrate due to the reduction in carbon implantation. Also, the addition of Xe having large mass number of 131 and large atomic radius of 2.17 angstrom has been confirmed to exhibit drastic suppression of the dopant deactivation, which results in low contact resistance without additional ion implantation after contact etch.