Design, Characteristics and Performance of Diamond Pad Conditioners

A wide range of diamond pad conditioner (disk) designs have been characterized and key performance metrics have been collected. Relationships between design characteristics including diamond size and shape, spatial density, and tip height distribution and polishing pad wear rates and pad surface textures have been established for a variety of pads. Estimation of the depth-of-penetration of working diamonds, from used disk analyses, allows meaningful topographic assessments of alternative conditioner designs and predictions of relative performance. An example of an improved conditioner that illustrates this design methodology is given. Conditioner aggressiveness and its decay in various slurries have been measured to assess disk lifetime in Chemical Mechanical Planarization (CMP) processes environments. Key factors affecting disk lifetime are discussed and an improved-lifetime conditioner for use in aggressive slurries will be reviewed. Introduction Diamond pad conditioners are used to prepare and maintain the surface of polishing pads used in CMP processes. The process advantages provided by proper pad conditioning have been reviewed elsewhere and include improvements in polishing rate and stability, planarization, and defectivity.1 Key performance attributes of diamond pad conditioners are cut and finish, similar to many other abrasive products. What is rather unique, compared to other abrasive processes, is that the workpiece (the CMP pad) is used in a subsequent (or concurrent) polishing process, and needs to possess very specific attributes for optimal performance. CMP pad choices have evolved beyond the basic hard porous pad to include those developed for more specialized applications. Formulations are now available that include softer pads and finer pore structures for improved defectivity with copper and advanced low-k dielectric materials, moredurable pads for improved life, and solid pads. Conditioning requirements for these new classes of CMP pads have driven the evolution of new pad conditioner designs. Slurry choices have also evolved and influence conditioner selection for a particular application. Reprinted from Mater. Res. Soc. Symp. Proc. Volume 1249 © 2010 Materials Research Society 1249-E02-04