Effects of aluminum sputtering process parameters on via step coverage in micro-electronic device manufacturing

Abstract

It has been observed that the step coverage achieved for aluminum deposition at 200°C on a multi-chamber (ultra-high vacuum) horizontal physical vapor deposition (PVD) system (System A) is electrically comparable to the step coverage on a single chamber, high vacuum (vertical) PVD system (System B) at 300°C under the optimized conditions of pre-clean process, sputtering power, argon pressure and chamber hardware configuration. In addition, it has been determined that the metal step coverage is relatively poor at temperatures higher than 200°C on System A, whereas the metal step coverage on System B is better at 300°C when compared with both substantially lower and higher temperatures. Since step coverage is a vital parameter in the manufacturing of sub-micron devices with high aspect ratio vias, the effect of the sputtering process parameters has been studied. This work investigates possible causes for the observed temperature effect and evaluates possible methods for improving the step coverage. The directionality of sputtering and film-substrate bonding are identified as two primary factors controlling step coverage.