Dual-thickness gate oxidation technology with halogen/xenon implantation for embedded dynamic random access memories

We investigated the enhanced oxidation effect of using silicon (Si) implant ed with fluorine (F), iodine (I), and xenon (Xe) before gate oxidation. I a nd Xe, which result in shallower implants because of their higher mass numb ers, were expected to be less damaging to the Si substrate. The resultant i ncrease in oxide thickness was found to be 20%, 80%, and 50% under F, I, an d Xe implantations with a dose of 5 x 10(14) CM-2, respectively. We found t hat F atoms outdiffuse to their ambient through SiO2, and that I implantati on causes the greatest increase in oxide thickness. In addition, F implanta tion shows highly reliable dielectric characteristics, low contact resistan ce, and a low junction leakage current. Consequently, the F implantation pr ocess is capable of providing reliable dual-thickness gate ox-ide for embed ded dynamic random access memories (DRAMs).