Method of forming dual-implanted gate and structure formed by the same

A method of forming a dual-implanted gate on a substrate having a gate oxide layer thereon, comprising the steps of:

• forming a plurality of stack structures on the substrate, wherein each stack structure belongs to a first group or a second group and each stack structure includes a polysilicon layer, a sacrificial layer and a mask layer;
• forming a dielectric layer over the substrate covering the stack structures;
• planarizing the dielectric layer to expose the upper surface of the mask layer within the stack structures;
• removing the mask layer to form a plurality of trenches;
• conducting a first ion implantation to implant first type ions into the stack structures belonging to the first group;
• conducting a second ion implantation to implant second type ions into the stack structures belonging to the second group;
• removing the sacrificial layer;
• forming a barrier layer over the substrate covering the interior surface of the trenches;
• forming a metallic layer over the substrate completely filling the trenches;
• removing the metallic layer and barrier layer above and beyond the trenches;
• and
• removing the dielectric layer to form gate structures.