Chemical-Mechanical Planarization Compatible for Both Copper/Low k Level in a 90 nm Technology and Thick Copper Level in an RF Technology

Abstract

The emergence of wireless communication technologies has increased the need for high performance radio frequency (RF) circuits as transceivers or filters (1). These functions imply high quality factor (Q) inductors. One way to reach such high Q value is to increase the ultimate copper thickness (above 3µm). Whereas Cu CMP has been widely reported as one of the leading techniques to integrate copper interconnects, many issues are still encountered for thick copper applications, where uniformity, topology and process time are major concerns. In this study, we develop a copper bulk CMP process compatible for both thick copper/low k interconnects and RF application. Starting from conventional sub-0.18µm slurry, an additive solution is added to enhance its removal rate. Results obtained on a 4 µm thick level are presented. It is shown that electrical performances are preserved, notably sheet resistance uniformity. Other usual CMP param eters, like planarization and consumables aging are also presented.