Microreplicated Pad Conditioner for Copper and Copper Barrier CMP Applications Wei-Tsu Tseng*, Sana Rafie, Adam Ticknor, Vamsi Devarapalli, Elliott Rill, Laertis Economikos IBM Semiconductor R&D Center, 2070 Rt. 52, Hopewell Junction, NY 12533, USA *weitsuts@us.ibm.com John Zabasajja # , Jennifer Sokol, Vince Laraia, Matt Fritz 3M Electronics Materials Solutions Division, St. Paul, MN 55144, USA # jnzabasajja@mmm.com Abstract— Metal-free micro-replicated conditioning disks are applied to the development of Cu and Cu barrier CMP processes for 22nm technology nodes. Compared with traditional pad conditioners with diamond grits embedded in metal matrix, the micro-replicated conditioners demonstrate lower within-wafer non-uniformity, more stable end-point time, more uniform and controllable pad wear, lower defectivity, and longer pad life time. Used pad analyses provide insights into the effectiveness of conditioning and guidelines for further process improvement. Keywords- Cu CMP; pad conditioning; microreplication. I. INTRODUCTION Pad conditioning has been the vital and integrated step during both oxide and Cu CMP in order to obtain and maintain an acceptable removal rate and stable process performance. The step helps maintain optimal pad surface roughness and porosity, ensuring slurry transport to the wafer surface and the removal of CMP residuals. Without conditioning, the pad surface will “glaze” and removal rates will decline rapidly. Diamond disks are the most widely utilized for pad conditioning in the industry today. The grit size, lay-out, and surface morphology of the diamond in the disk matrix all play critical roles in the rates and uniformity of CMP [1-3]. Given the ionic strength of the slurries and the nature of the abrasives, however, chemical or abrasive wear of the conditioner itself can be sufficient enough after hours of service such that rates and uniformity begin to drift. In fact, one recent study indicates that diamond micro wear and corrosion of metal substrate both occur during Cu CMP [4]. The debris of diamond wear can result in heavy scratches on Cu surface. In addition, the corrosion of conditioner metal substrate and hence the introduction of metallic ions onto wafer surface will pose serious reliability concerns for Cu interconnects. In this work, two novel metal-free, microreplicated pad conditioners, M1 and M2 are demonstrated for Cu and Cu barrier CMP. These pad conditioners are made with precisely engineered surfaces designed to provide pad cutting and cleaning action while maintaining the desired surface topography and low pad wear rates. Microreplication allows each pad conditioner to be manufactured with the exact same abrasive surface, thus reducing CMP process variability. Figure 1 shows a typical diamond grit surface of a conventional pad conditioner compared with that of a microreplicated conditioner. Fig. 1. Paradigm shift to new pad conditioning technology. The differences between disks M1 and M2 designs are shown in the micrographs in Figure 2. M1 has regular square pyramid structures with about 75% primary features with sharp tips and a small height offset from secondary features yielding a medium to low aggressive conditioner. Fig. 2. SEM micrographs showing surface of M1 and M2 conditioners with microreplicated structures. On the other hand, M2 has a variety of complex multi faceted structures with 5% primary features. These sharp-tipped features have a larger height offset from secondary ones as compared to M1, yielding a more aggressive conditioner. In both pad conditioner designs the number of primary abrasive tips determines the relative aggressiveness of the disks. Both M1 and M2 disks are applied to Cu and Cu barrier