ICMCTF1998 Session H7: Technological Challenges of 300mm IC Substrates

The planar magnetron sputtering source and its close relatives have become the preferred instrument for metallizing silicon wafers for integrated circuit manufacturing. However, as the semiconductor industry moves to 300mm diameter wafers, a simple scale-up of the sputtering cathode mandates a larger target diameter and, consequently, a significant increase in its mass. The increased diameter can lead to additional deflection of the target due to the differential pressure across it, while a much larger target mass poses new handling difficulties in the cleanroom. Coincident with the transition to larger diameter wafers, critical device dimensions continue to shrink, and new dielectric and conductor materials are being introduced to improve performance and reduce costs. New magnet assemblies that provide superior film uniformity through target life and more efficient target utilization are therefore required. The increasing importance of ionized physical vapor deposition (i- PVD) must also be considered in cathode design.

This paper describes the numerous issues that relate to PVD and i-PVD source development for 300mm diameter wafers, and highlights the various factors that must be balanced in the design process. For example, advanced cooling schemes, the impact of target to wafer distance on source dimensions, and the advantages and disadvantages of scanning the cathode (or the wafer) compared to conventional DC magnetron sputtering, are discussed.