Recent advances in the application of collimated sputtering

Abstract

The "W-Capped Aluminum Damascene Process" forms low-resistance wiring for the IBM/Siemens 64 MB dynamic random access memory (DRAM). Damascene wiring is fabricated by etching a trough in a dielectric, filling the trough with metal, and planarizing back to the dielectric surface. For the 64 Mb DRAM, collimation is used to enhance fill of the recessed features. This paper reports the results of our recent work to optimize the processes. Specifically, we have investigated the trough-fill capability of the Al and Ti films as a function of process parameters, deposition hardware, and the oxide trough aspect ratios. In addition, we have improved the manufacturability of these processes by modifying the collimator design to increase deposition rate and lengthen collimator life. Finally, we report the first demonstration of an Al-based dual-damascene structure combining collimated sputtering and chemical vapor deposition (CVD) W. Dual damascene combines fabrication of the wires and studs by etching both recesses in the same dielectric and filling them simultaneously, thereby simplifying the process flow and lowering fabrication costs. © 1994.