Octadecaborane implant technology for 72nm node stack DRAM p+ poly gate doping process

Abstract

Octadecaborane (B 18 H 22 ) implant technology was evaluated for p+ poly gate doping process in a 72nm node stack DRAM device. The evaluation criteria were to improve the productivity of the process, which was initially built with conventional atomic boron implantation ( 11 B), while maintaining process equivalency. Before implanting into device wafers, process matching to conventional boron implant was done using both crystalline silicon and poly-silicon on Si wafers. For the crystalline silicon wafers, the R s of blanket B 18 H X + implants were compared to that of atomic boron. For the poly-Si silicon wafers, SIMS dopant profiles were compared. For the device wafers, boron penetration, gate depletion, and final yield were compared. In addition, B 18 H 22 implant splits of various energies and doses have been studied for their sensitivities to the electrical performance of the p-MOSFET in the 72nm node stack DRAM devices. In this study, we have demonstrated that B 18 H 22 can provide up to 5X wafer throughput advantage over conventional atomic boron process due to much higher effective beam currents. Besides the significant productivity improvement, B 18 H 22 implant device characteristics were well matched to the baseline atomic boron process.

High Mass Molecular Ion Implantation for Advanced Logic and Memory Devices Manufacturing

“…As the dosage gets high, the Vth gets high too. However, the biggest deviation is less than 10mV, we can say that the device results are all meeting the specification (Chang, 2008).…”

“…The evaluation criteria were to improve the productivity of the process, which was initially built with conventional atomic boron implantation ( 11 B), while maintaining process equivalency. Before implanting into device wafers, process matching to conventional boron implant was done using both crystalline silicon and poly-silicon on Si wafers (Chang, 2008). For the crystalline silicon wafers, the R s of blanket B 18 H X + implants were compared to that of atomic boron.…”