In situ measurement of the bonded film thickness of Z-Tetraol lubricant on magnetic recording media

摘要

Currently, the bonded film thickness of perfluoropolyether lubricant on top of magnetic recording media is measured by a two-step process. First, the media disk has to be rinsed thoroughly using a fluorocarbon solvent (for instance, Vetrel) to remove the mobile lubricant. Second, the thickness of the remaining lubricant on the media surface which is regarded as the bonded lubricant thickness is then measured either by Fourier transform infrared spectroscopy (FTIR) or electron spectroscopy for chemical analysis. As the total lubricant thickness approaches single molecular dimension (～10 A), current methods face tremendous challenge on the accuracy and sensitivity of the measurement. We studied the spectral characteristics responding to the lubricant bonding with the carbon overcoat by the time-of-flight secondary ion mass spectra and proposed to use the peak area ratio (C_3H_2F/C_3H_5O and C_4H_(10)O/C_3H_6O_2) to characterize the bonded Z-Tetraol lubricant that produces a direct bonded lubricant thickness measurement without the need to remove the mobile lubricant with a solvent. After taking the background signal of disks prior to bonding by UV irradiation into account, this method becomes independent of the total lubricant thickness as well as shows good correlation linearity (R~2～87%) with the current FTIR method for the ratio of C_4H_(10)O/C_3H_6O_2.