and squareness the deposition process can be done by various thin film deposition techniques including ion beam deposition ibd plasma enhanced chemical vapor deposition pecvd magnetron sputtering radio frequency sputtering or chemical vapor deposition cvd next in step 330 the protective overcoat layer 225 is deposited over the magnetic stack the protective overcoat layer 225 which is typically diamond like carbon dlc can be deposited using a variety of thin film deposition techniques including ion beam deposition ibd plasma enhanced chemical vapor deposition pecvd magnetron sputtering radio frequency sputtering or chemical vapor deposition cvd in one embodiment the dlc protective overcoat layer 225 is prepared by ion beam deposition using a work gas is c 2 h 2 the energy per c atom is 90 ev next in step 340 the dlc protective overcoat layer 225 is exposed to uv light while being exposed to a hydro phobic chemical environment typically this includes exposing the magnetic media having the dlc protective overcoat layer 225 to uv light for a fixed amount of time the amount of time needed varies from lubricant to lubricant and is typically around 120 seconds also the amount of time needed is a minimum threshold that sufficiently fills the voids in the protective overcoat 225 to prevent diffusion of moisture through to the magnetic layer the amount of time depends on the type of hydrophobic chemical being used some examples of hydrophobic chemicals used include low molecular weight perfluoropolyether fluoroalkane fluoroether chlorofluoroalkane chlorofluoroether vertrel xf etc in addition to just varying the time of uv light exposure other.