We modified a polycide gate etching chamber of an Applied Materials Precision 5000 platform to accept a commercially available Prototech 150-mm-diam helical resonator plasma source to extend the utility of this proven manufacturing platform to 0.25 mu m technology and beyond. We successfully demonstrated the use of the helical resonator on the Precision 5000 platform to etch WSix/alpha-Si gate stacks using a multistep process. At low pressures (<10 mTorr), the helical resonator etches polysilicon and WSix more uniformly than a standard Precision 5000 MERIE chamber. In addition, the WSix-to-alpha-Si selectivity for the WSix etching step is also higher with the high-density source.