The demand for increased storage capacity in memory or rigid disks and the trend towards miniaturization of memory or rigid disks (due to the requirement for smaller hard drives in computer equipment) continues to emphasize the importance of the memory or rigid disk manufacturing process, including the planarization or polishing of such disks for ensuring maximal performance. While there exist several chemical-mechanical polishing (CMP) compositions and methods for use in conjunction with semiconductor device manufacture, few conventional CMP methods or commercially available CMP compositions are well-suited for the planarization or polishing of memory or rigid disks.
As the demand for increased storage capacity has increased, so has the need for improved processes for the polishing of such memory or rigid disks. The term “memory or rigid disk” refers to any magnetic disk, hard disk, rigid disk, or memory disk for retaining information in electromagnetic form. The memory or rigid disk typically has a surface that comprises nickel-phosphorus, but the memory or rigid disk surface can comprise any other suitable material. The planarity of the memory or rigid disks must be improved, as the distance between the recording head of a disk drive and the surface of the memory or rigid disk has decreased with improvements in recording density that demand a lower flying height of the magnetic head with respect to the memory or rigid disk. In order to permit a lower flying height of the magnetic head, improvements to the surface finish of the memory or rigid disk are required.
Surface roughness is a high frequency, short wavelength component of a measured surface which affects performance of memory disks insofar as it limits the decrease in the gap between the disk surface and the recording head of a disk drive that is practically achievable. Thus, reduction in surface roughness of memory disks is highly desirable from a performance standpoint. Attempts have been made to reduce surface roughness by utilizing abrasives having smaller particle size in polishing compositions for memory disks. However, typically smaller abrasive particles result in a reduction of removal rate of the surface of memory disks, which increases the amount of time required to achieve a desired surface finish, thereby increasing production time and costs. Accordingly, there is a need in the art for methods for polishing memory disks that produce decreased levels of surface roughness while exhibiting increased polishing rates.