Fabrication Process of a High Performance Write Head
Original Publication Date: 2002-Sep-12
Included in the Prior Art Database: 2003-Jun-21
The quest for higher areal density in magnetic recording necessitates the use of materials with high saturation magnetization in the write head. It is found that the use of sputtered CoFeN as a first layer followed by a plated 30/70 (atomic NiFe in the P2 write pole gives superior overwrite and SER performance compared with a P2 with only NiFe. The CoFeN is composed of 25% to 45% of Co, 55% to 75% of Fe and less than 1% of nitrogen. However, the processing of this material combination (CoFeN/NiFe) is proven problematic with the widely used aqueous based lapping and cleaning processes due to Galvanic corrosion of the CoFeN layer. The images below show a SEM image of a clean (left) and corroded slider (right). The line trial of this structure over a 4 month period showed that a few percent, of sliders, would corrode during fabrication and therefore is not a manufacturable process without 100% screening. It is evident that the POR process does not yield a corrosion free product and needs improvement. While it is reasonable and is proven that the complete removal of water in the fabrication process would eliminate in-process corrosion, such a solution is very expensive to implement, primarily due to the numerous cleaning steps in the process. It is also difficult to find a nonaqueous solvent that can match the good solvency property of water and is safe to use in a high volume manufacturing environment. In addition, aqueous cleaning is more environmentally friendly and would not result in any emission of volatile organic materials in the atmosphere. The present invention discloses a fabrication process of the said bilayer structure that uses a nonaqueous but water soluble lapping slurry followed by aqueous cleaning with a nonionic surfactant as cleaner. The water-soluble lapping slurry is composed of diamond particles suspended in 100% ethylene glycol or mixed with isopropyl alcohol or other alcohols (0 to 10%), to minimize corrosion in the cleaning process after lapping. It is important that only nonionic surfactants, such as Alfonic, are used in the brush cleaners. The concentration of the nonionic surfactant in water ranges from 0.1% to 0.4% (vol %). Repeated experiments using these process combinations showed no corrosion of the CoFeN or the NiFe layers in the write poles.