计算机硬盘基片CMP中表面膜特性的分析研究

目前，普遍采用化学机械抛光(Chemical-mechanical polishing，CMP)技术对计算机硬盘基片(盘片)表面进行原子级平整。CMP加工中，盘片表面膜及其特性对CMP过程及CMP性能具有关键作用。本文分别采用俄歇能谱(AES)、X射线光电子能谱(XPS)、扫描电镜(SEM)、纳米硬度计、电化学极化法等分析手段对盘片表面物理、化学及机械特性进行了研究，发现盘片CMP后表面发生了氧化，氧化膜在盘片的表层,厚度在纳米量级，氧化产物为Ni(OH)₂；氧化膜为较软的、疏松的、粗糙的多孔结构；氧化膜的存在加快了盘片表面的腐蚀磨损。结合盘片CMP试验结果，推测盘片的CMP机理为盘片表面氧化生成机械强度较低的Ni(OH)₂氧化膜及随后氧化膜的机械和化学去除，二者的不断循环实现表面的全局平面化。

Properties of Surface Oxidation Film in CMP of Computer Hard Disk Substrate

Chemical mechanical polishing (CMP) is widely used to obtain the atom-scale planarization surface in the manufacturing of computer hard disk substrate. During CMP, surface properties of hard disk substrate play a key role to the CMP performances. The physical, chemical and mechanical properties of hard disk substrate surface were investigated by using Auger Electron Spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nanoindentation, and elecrochemical polarization analyses. The results indicate that the oxidization reaction occurrs on the surface of hard disk substrate after CMP process. The oxidation film contains Ni(OH)₂ with a nanometer thickness. And the oxidation film is softer than the substrate with a loose, rough and porous structure. The introduction of oxidation film increases the corrosion wear rate during CMP of hard disk substrate. Combining the surface properties of hard disk substrate with the results of material removal rate and surface roughness after CMP tests, the CMP mechanism of hard disk substrate is proposed as follows: the oxidization of disk substrate surface to form Ni(OH)₂ oxidation film with low mechanical intensity and the following chemical dissolution and abrasive wear of the oxidation film, the continuous circulation between the formation and removal of the oxidation fim on the disk substrate surface to realize the global planarization.